CommercialBlueberry

Production

CommercialBlueberry Production

Table of Contents

Introduction and History................................................................................ 4Potential for Commercial Blueberries.............................................................. 4Budget Considerations................................................................................... 5Site Selection................................................................................................. 5Soils.............................................................................................................. 6General Soil Areas in Louisiana...................................................................... 7Site Preparation and Planting......................................................................... 9Water Source and Quality.............................................................................. 11Irrigation....................................................................................................... 12Weed Control................................................................................................ 18Plant Nutrition.............................................................................................. 21Fertilization Program...................................................................................... 23Pruning......................................................................................................... 25Mulching....................................................................................................... 25Cultivar Selection........................................................................................... 26Propagation.................................................................................................... 29Insect Identification and Control.................................................................... 30Disease Identification and Control.................................................................. 34Acknowledgments......................................................................................... 35

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Introduction and HistoryCommercial blueberry

production in Louisianahad its beginning morethan 40 years ago withthe introduction ofimproved varieties of

rabbiteye blueberry(Vaccinium ashei). Since then,

acreage has increased steadily.

Commercial blueberry production has been aviable industry throughout the United States for 50years. Several blueberry species are native to thiscountry. The high bush (Vaccinium corymbosum) andlow bush (V. Angustifolium) species are adapted to thenorthern climates.

Rabbiteye blueberries are native to thesoutheastern United States, growing from the easternsections of Texas to the Atlantic coasts of Virginiaand Florida. The rabbiteye blueberry is not to beconfused with the huckleberry (Gaylussacia genus).The two are distinguished from each other by theirnumbers and types of seed. The huckleberry has 10large bony seeds, and the rabbiteye has numeroussmall seeds.

New hybrid cultivars of blueberries are beingdeveloped by geneticists who incorporate the higherfruit quality and shorter ripening period of theTetraploid northern high bush blueberries with theDiploid and Hexaploid blueberries indigenous to theSouth. These newer cultivars, which ripen earlier thanrabbiteye blueberries, can extend the marketingseason and take advantage of premium prices beforethe eastern blueberries are available on the market.The Tetraploid cultivars (also known as southernor low-chill high bush) will increase in importanceas more varieties are developed.

The rabbiteye species is the primary type growncommercially throughout the Southeast. Itsimportant mainly because it grows on locations withmore upland soil types than does the high bushblueberry. Also, the rabbiteye blueberry is not assensitive to soil acidity and is far more heat- anddrought-resistant than is the high bush blueberry.

Potential for CommercialBlueberries

Commercial blueberry potential in Louisianacan be measured in terms of how well you select asite, choose cultivars and plan for cultural practices.Production costs in Louisiana compare favorablywith costs in other areas with commercial plantings.Marketing strategies and labor needs are two mostimportant ingredients necessary for success.

A complete marketing program cannot beadequately outlined within the scope of thispublication. Yet, marketing should be the one aspectof commercial blueberry production on which agrower spends the most time. Small one- to three-acre plantings can often be marketed as a pick-your-own (PYO) crop. But, PYO success in a given area isdirectly related to population and number ofcompeting producers. Larger acreages need a moresophisticated marketing strategy pivoted on a reliablelabor pool.

Although mechanical harvesting is available,most blueberries are harvested by hand. Mechanicalharvesting is very expensive, and large acreage isneeded to support this expense. Mechanicallyharvested blueberries can be sold on the fresh marketonly after they are cleaned and sorted. This requires awell-adjusted machine, a successful operator, propertiming of harvest and suitable cultivars. Not all theblueberries on a plant can be harvested on a singledate because not all fruit ripens together. In thefuture, determinant ripening cultivars and improvedtechnology may minimize this problem.

Exporting fresh blueberries to other states beforethe eastern varieties ripen has the most potential. Thefirst blueberries from early cultivars are picked aboutMay 15 in North Carolina, June 15 in New Jerseyand June 10 in south Louisiana. Rabbiteye blueberriesare late ripeners, with Louisianas first week ofproduction usually in early June in south Louisianaand mid June in north Louisiana. This time frameoverlaps the second half of the North Carolina highbush harvest, but precedes the larger New Jerseyharvest, opening an excellent marketing window forearly June. Eventually, a May shipping season mightbe possible in Louisiana as earlier ripening rabbiteye

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cultivars and disease-resistant high bush cultivars aredeveloped.

Grower marketing cooperatives such as theMiss-Lou Co-op offer excellent opportunities forproducers to consolidate their marketing andpurchasing of supplies for a more cost-effectiveoperation. The Miss Lou Co-op has, since itsbeginning, been an excellent marketing tool forMississippi and Louisiana producers. All producersshould consider joining.

Budget ConsiderationsCosts and expenses of establishing and

managing blueberry acreage vary, depending onexisting resources and levels of expertise of individualproducers. The initial investment can be large if land,labor and machinery are purchased and charged to thecost-return ledger. Yet, many potential producers mayalready be involved in other phases of agriculture andhave available land and resources that make the initialfour years before the first paying crop less costly. Theinputs for establishing and maintaining a blueberryplanting follow. The total cost for the first year isabout $3,000 per acre plus land cost. Most of thisgoes for purchasing plants, installing an irrigationsystem, mulch, peat moss and labor. Maintenancecosts in years two through four are about $500-$1,000 per acre per year.

Inputs per acre required to establish ablueberry farm.

First YearLandPlants (604 plants per acre)Irrigation installationPlow land, once, 0.5 hour (tractor, plow and

driver)Disk harrow, twice, 0.3 hour each (tractor, disk

and driver)Lay off rows, once, 0.5 hour (tractor and driver)Open furrows, twice, 0.3 hour each (tractor and

driver)Apply peat moss, once, 2.0 hours (tractor, trailer

and driver)Fertilize, 5 times

Set blueberry plants, 5.0 hours (tractor, trailerand driver)

Mulch beds, 5.0 hours (tractor, trailer and driver)Irrigation electricity

Second and Third YearsFertilize 5 timesSpray 5 times, 0.5 hour each (tractor, sprayer and

driver) (herbicides and fungicides as recom-mended)

Mowing, 10 times, 0.4 hours each (tractor,mower and driver)

Pruning and hoeing (20 hours)Irrigation electricityInterest on establishment and pre-harvest costsHarvesting and marketingPicking laborLabor benefitsContainersMarket preparation (including marketing and

advertising)TransportationSupervision

Site SelectionSite selection should be based on several factors.

Market ConsiderationsIt is critical to choose a site close to a large

population if PYO is the primary means ofmarketing. Such a site should be located on a majorthoroughfare, if possible, with the planting visiblefrom the road. Market proximity is not as criticalwhen the primary market is the wholesaler, but areliable labor pool should be available.

Climatic ConditionsThe rabbiteye blueberry is deciduous and

requires a given amount of exposure to cold weatherto satisfy chilling requirements and to induce flower-ing. The chilling requirement of rabbiteye blueberries(200-600 hrs.) is below that of high bush (650-800hrs.). With inadequate chilling, both vegetative andflower buds grow unevenly. Flowers from such buds

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will not set fruit. Therefore, do not plant rabbiteyeblueberries along the coastal areas of Louisiana wherechilling is commonly insufficient.

TopographyAvoid frost pockets by selecting elevated sites

with open areas surrounding the planting. Freeze-outs are possible, particularly in north Louisianaduring early spring when blueberries are in bloom.Open, well-ventilated areas also create a betterenvironment for disease control. Avoid low areaswhere floodwaters may inundate a blueberryplanting.

SoilsBlueberries have specific soil requirements and

cannot be grown commercially on a wide varietyof soils.

Blueberries require an acid, well-drained soil.Soil pH should be in the range of 4.2-5.5. Adviceand counseling on soil testing can be obtained fromyour county agent. See section on soil testing.

pHGood production in some soils with pH up to

6.0 may be possible, but nutritional problems such asiron deficiency may occur at high pH levels.Conversely, blueberries begin to lose productionefficiency because of nutrient toxicities by manganeseand aluminum, or potential nutrient deficiencies ofcalcium, magnesium, copper, boron andmolybdenum at soil pH levels below 4.2. Thehigher pH soils can be adjusted to 5.5 by addingpowdered sulfur. Lower pH soils can be raised byadding fine limestone. Both amendments need to beapplied six months to one year before planting. Baserates on soil tests. Certain cultural practices maylower the soil pH. Adding peat moss at planting andusing ammonium forms of nitrogen during thegrowing season will help lower pH.

Adjust soils with a pH above 6.0 to pH 5.4.Determining the amount of sulfur to add to obtain aspecific pH level in the soil is not an exact science,and the application can be overdone. Sandy soils canbe slightly acid in the top 6 inches because ofprevious nitrogen fertilization but still have analkaline reaction in the subsurface depths. Such soils

require pH adjustment for successful blueberryproduction, but an adjustment may be difficult andtoo costly.

Avoid sites where brush and timber have beenburned. The basic minerals of ash will raise the soilpH above the range for best plant growth. Avoidrecently limed land unless the lime was applied toraise the soil pH into the favorable range forblueberries. A soil test showing more than 900pounds of available calcium per acre indicates that thesoil was recently limed, and production problemsmay occur.

Soil TextureSoil texture refers to the relative proportions of

sand, silt and clay in a given soil. Soils are referred toas sands, loams or clays based on the proportions ofeach. Blueberry plants grow best in loam or sandyloam soils. The fine fibrous root system of theblueberry plant requires open, porous soils. Theseroots cannot penetrate compact, heavy clay soils.Blueberry plants grow best in soils containing largeproportions of sand. Blueberries will grow in claysoils which have been amended with high levels ofacid peat, but root growth is restricted.

Soil Organic MatterNumerous reports refer to the importance of

soil organic matter for blueberry production. Soilswith potential for blueberry production in mostsouthern states are usually low in organic matter. Mixpeat with the soil at planting to overcome thisdeficiency. Milled pine bark will work about as wellas peat and may be substituted.

Soil Depth and HorizonWhen selecting a site, consider depth and

horizon of potential soils. Soil horizons are layers ofsoil nearly parallel to the soil surface with distinct soilproperties such as color, depth, organic mattercontent, pH and texture. Soils are classified accordingto their horizons and properties of these horizons.The surface horizon of an ideal soil for blueberryproduction contains 4 to 8 inches of a darker sandyloam and organic matter. This is the A horizon.

The next horizon of ideal blueberry soil is paleand lower in clay and organic matter content fromeluviation (solubilization and leaching) of thesematerials. This is the E horizon. Areas in planted

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fields where bushes die, or grow slowly, are oftentraced to the lack of an E horizon becauseblueberry plants do not grow as well in low organicmatter clay soil as they do in sandier, moreeluviated soils.

A third soil horizon desirable for blueberryproduction should occur from 24 to 40 inchesbelow the soil surface. This B horizon is oftencharacterized by a concentration of silicate clay thathas moved down from the A and E horizons.The B horizon is desirable in soils used forblueberry production because it increases the soilswater retention.

Deep sands and other soils of low fertility andlow water-holding capacity are marginally adaptedfor blueberry production. But, they can be used ifproperly fertilized and treated with organic matterand if an ample supply of good quality irrigationwater is available. Generally, sands deeper than 60inches are too dry for good blueberry productionduring extended low rainfall periods.

Soil DrainageAdequate soil drainage is essential. Land is too

wet for blueberries if the water table does not drainto a depth of 24 inches or more below the soilsurface within 24 hours after a heavy rain. Gray clayin the subsurface horizons and closer than 24 inchesbelow the soil surface indicates a potential problemwith the water table. Red or yellow subsoils arepreferred. The red color, like iron rust, means thatthe subsoil is well aerated and has no problem withexcess water.

General Soils Areas in LouisianaThe general soil areas are shown in Figure 1.

They are (1) coastal marshlands, (2) recent alluvium,(3) coastal prairies, (4) flatwoods, (5) loessial hills andMississippi terraces and (6) coastal plain.

Coastal marshlands soils are generallyunsuitable for commercial blueberry culture. Thesesoils, although highly organic, are generally wetlandssubject to inundation.

Mississippi alluvium soils are represented bythree soil types. The Commerce soils are on the lownatural levees that represent the highest elevation of

flood plain. The Sharkey soils occupy level areas anddepressions of the back swamps at low elevation.Mhoon soils are in the broad, level areas lying betweenthe Commerce and Sharkey soils. Of these three soiltypes, only the Commerce soils have limited potentialfor commercial blueberries because of their moreacceptable aeration and oxidation. But, these soils arenot generally recommended for commercialblueberries.

Alluvium soils of the Red and Ouachita rivers.The major soil series of these young alluvial soils areNorwood, Yahola, Moreland and Perry. Norwood andYahola soils occupy low natural levees at the highestelevations of the flood plain. The Perry soil is in flatsand depressions of the back swamp areas. Morelandsoils typically occur between the level levees and backswamps. The friable Norwood and Yahola soils areaerated and oxidized, well-drained and generallysuitable for blueberry culture. Moreland and Perry soilsare clayey throughout and poorly oxidized and are notgood blueberry soils. The pH of the Red River soils isgenerally in the high range (6-7) and should bemonitored closely before considering commercialblueberries. The pH of these soils is not easily alteredpermanently. They may not be acceptable forblueberries.

Coastal prairie soils are the Crowley soils andMidland soils. Associated with the soils of the coastalprairies is the Acadia soil that occupies the forestedslopes along stream channels that cross the prairies. Ofthese three, only the Acadia soil is suitable forcommercial blueberries. The Acadia soil has a friablesilt loam surface layer with a weak, granular structureand mottled gray, brown and red clay subsoil that isfirm when moist. Both the Crowley and Midland soilseries have poorly drained upper strata with gray siltclay subsoil that restricts vertical drainage. They are notsuitable for blueberries.

Flatwoods soils are flat and nearly level areas ofpoorly drained and somewhat poorly drained forestedsoils. The largest areas of flatwoods soils are insouthwestern and southeastern Louisiana. In thesouthwest, the dominant soils are in the Caddo andAcadia series that occur on the level and nearly levelridges, and the Beauregard and Acadia series that occuron side slopes. Other than the Acadia series, they areconsidered marginal for blueberries.

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Figure 1. General Soils of Louisiana

Gently Sloping to Hilly Coastal Plain -Shubuta, Ruston, Bowie, Lucy, Troup, Kirvin,Nacogdoches, Susquehanna, Ora, Sawyer, Boswell,etc., with Cahaba, Prentiss, Stough

Loessial Hills and Mississippi Terraces -Olivier, Loring, Memphis, Providence, Lexington,Calhoun, Jeanerette, etc., with Cascilla, Waverly,Collins

Flatwoods Areas - Caddo, Beauregard,Acadia, Frost, Calhoun, Zachary, Wrightsville, etc.,with Bibb, Waverly

Coastal Prairies - Crowley, Midland, withBeaumont, Bernard, Acadia

Mississippi River Alluvial Soils - Sharkey,Mhoon, Commerce, Tunica, etc., with Cypremort,Dundee, Baldwin, Iberia, Jeanerette

Alluvial Soils of the Red and OuachitaRivers - Moreland, Norwood, Yahola, Perry,Portland, etc., with Gallion, Hebert, Pulaski

Coastal Marshlands - Marsh Peats,Mucks, Clays and Harris, with Swamp Peats, Mucksand Clays

The northeast Flatwoods includes thesomewhat poorly drained Olivier soil on level andnearly level ridges that lie a few inches above thepoorly drained Calhoun and Frost soils with Zacharysoils in flat depression along drainways. These soilshave rather friable surface layers overlying a firmfragipan layer. Poor vertical drainage makes thesemarginal for blueberries.

Loessial hills and Mississippi terrace arerepresented by Memphis soils on level and slopingridges and steeper side slopes, the Loring on gentlysloping ridges and side slopes, the Olivier on nearlylevel and gently sloping ridges and on seepy footslopes, and Calhoun on level tops of ridges, on flatsand in depressions. All of these soils are siltythroughout. They have friable silt loam surface layersand friable to firm silt clay loam subsoils. TheMemphis soil is well drained and of all these series ismost suited for blueberries, followed by the Loringseries which is, at best, marginal.

Coastal plain soils occur in the area ofpredominately pine-forested slopes and hills locatedmainly in the northern half of the state. The majorsoil series of the coastal plain area are separated intothree groups on the basis of soil permeability:permeable subsoils, moderately permeable subsoilsand slowly permeable subsoils.

In the permeable subsoil coastal plain soils arethe Ruston, Lucy, Troup and Bowie series, all ofwhich have sands or sandy loam subsoils best suitedfor blueberries. Moderately permeable subsoils of thecoastal plain soils are represented by theNacogdoches, Shubuta and Ora series. Only the Oraseries, because of the fragipan subsurface, ismarginal for blueberries. The Nacogdoches areconsidered good blueberry soils with ironstonecommonly occurring in the subsoil or throughoutthe soil profile.

The slowly permeable subsoil coastal plain soilsgroup includes three soil series: Boswell, Susquehannaand Sawyer. These soils can be suitable for blueberryculture, depending on depth of topsoil and quality ofsubsoil. The deeper surface layers of sandy loam arebest. These soils are generally underlaid with acidclays. The deeper the surface soils are separated fromthe poorly drained subsoil, the more suitable thesesoils are for commercial blueberries.

Soil TestingSoil testing of a prospective blueberry site

should begin one year before planting. Such testsdetermine nutrient content of the top 6 inches ofsoil, pH and calcium levels and determine the poten-tial manganese and aluminum toxicity to blueberryplants. They also indicate the fertilizer requirementsof that soil for nitrogen, phosphorus, potassium,calcium, magnesium, sulfur and micronutrientsnecessary to support vigorous plant growth. Subsur-face samples should be taken to determine the pHand carbonates level. This indicates the presence orabsence of native lime in these lower depths.

Collect both surface (2 inches to 4 inches) andsubsurface (8 inches to 10 inches) samples fromrandom locations in a prospective site. All individualsamples can then be combined to form a compositesample. It is important to keep subsurface and surfacesamples separate. Your county agents office hassampling instructions.

Site Preparation and PlantingSite preparation should begin one year before

transplanting. It consists of land clearing and leveling,design, preplant weed control, subsoiling, cultivationand bed preparation.

If the selected site is wooded, clearing should bedone well before planting. If trees and brush arebulldozed, do not burn them on the planting site.Wood ash leaves a chemical residue that can raise thepH for long periods. Remove trees and brush beforeburning.

On flatwood soils or other poorly drained soils,correct surface drainage problems. Leveling to fill lowspots should be done carefully so you dont removeexcessive topsoil.

Ditch digging, bed construction and otheroperations that mix soil horizons may affect soil pHadversely. Problems should not be severe if the soilpH is suitable, but high pH spots created by mixingsoils should be treated with sulfur before planting.

Orchard Planting Design: The irrigationsystem is an integral part of the planting design andmust be considered in this phase. If the site has asignificant slope, then contouring of rows may be

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necessary. The greater the slope, the greater thepotential for erosion. Row spacing should be on 12-foot centers with plants spaced 3 feet to 6 feet withinthe row. A 12-feet x 6-feet spacing, the spacing mostcommonly used, will result in a plant density of 605plants per acre.

The standard spacing for blueberries is 6 feetbetween plants and 12 feet between rows with 605plants per acre. A closer spacing of 5 feet in the row isrecommended for mechanical harvesting. Regardlessof spacing used, the row eventually becomes asolid hedge.

Preplant Weed Control: Treat sites that havetroublesome perennial weeds, such as bermuda andbahia, well before planting. Eradication of mostweeds can be accomplished with a broadcast applica-tion of a nonselective herbicide such as Roundup. Ifthere is the potential for soil erosion, or if the field isalready in a desirable sod, weed control strips at eachrow location may be advisable. Carefully mark rowsto ensure proper herbicide placement. This will allowan erosion control sod to remain between rows.

Soil Preparation: Any necessary adjustments tosoil pH can be lowered by discing in powderedsulfur. There are practical limitations as to how lowthe pH can be adjusted. On soils naturally high inpH, the pH tends to return to its original levels as theeffects of the sulfur wear off. Blueberries should notbe planted on such soils. Sulfur is used effectively onsoils that are naturally at 5.5 pH or lower and onsoils that were acid in their native conditions butpreviously limed.

The pH adjustment with sulfur should beginsix months before planting. If the pH is 5.4 or lower,do not adjust. Otherwise the amount of sulfur to beadded is one pound per 100 square feet (500 poundsper acre) for every pH point above 5.4. Treat theentire site without regard to row location. Cultivatethe field at least twice at seven- to 10-day intervals.This allows any remaining plant debris to dry out.

After cultivation, the site should be subsoiled atrow locations. This promotes deep root penetrationof blueberry plants. On heavier clayey soils, cultivatein organic matter such as pine bark into the plant rowto improve soil structure. Cultivate sufficiently todevelop a well pulverized, finely textured soil. Rowsshould be bedded on sites with poor surface drainage

or with slopes of more than 6 percent. Using aturning plow, construct beds 4 to 10 inches high,flattened or slightly crowned.

PlantingIf the soil is well tilled, planting will be simple.

Poorly prepared sites will make planting difficult.Prepare the planting holes early to allow for moistureequalization of the soil and peat amendments. Makeholes 18 inches to 24 inches in diameter and depth. Ahand-dug hole may be practical for small plantings,but for large plantings use a tractor-mounted, power-off, auger-type digger. If an auger is used, score thesides of the hole with a shovel or sharp shooter.Scratches welded onto the auger will prevent glazingor compaction of the walls of the planting hole.Glazing of the walls of a planting hole will cause thehole to hold water much like a well. This can damageyoung plants.

Studies have shown that peat moss is beneficialto the survival and growth of blueberries. Because ofthe expense of peat moss, combinations of peat andfinely ground pine bark or pine bark alone may besubstituted. Use 1/3 cubic foot of peat moss perplanting hole to form a 50:50 soil: organic mixture.

Mix soil with the peat in the hole. Other soilamendments, except nitrogen, may be added at thistime. Such amendments are based on soil tests. Beforeplanting, allow the soil and peat mixture to moisteneither through rainfall or irrigation. To avoid drying,do not open the holes until just before planting.

Containerized plant handling. Do not allowcontainerized plants to dry out before planting. Theycan be planted any time, but late fall or early spring isoptimal. Thoroughly break up the root ball at thetime of planting. Be sure roots are spread into thefreshly reopened planting hole. Breaking the rootballresults in two to three times the growth in the firstseason when compared to plants with non-brokenrootballs. Set plants slightly deeper than they weregrown in the container. After replacing the soil andpeat mixture, tamp the area lightly to fill all of theair pockets.

Bare root plant handling. The root systemmust remain moist until planted. Bare root plantsshould be planted only during the dormant season.Keep the root system covered with wet hay or peatmoss at all times. Set plants at the same depth they

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grew in the nursery. As soon as the bare-rooted plantis planted, prune the plant back 25 percent to 30percent.

Other factors. The irrigation system must beready to use as soon as plants are placed in theground. Water all plants immediately after planting.Plantings have failed when allowed to stand dry whilethe irrigation system was being installed.

Young plants are poor competitors with weeds.The area at the base of the plant must be kept weed free.

Water Source and QualityBefore establishing a commercial planting of

blueberries, obtain an ample supply of high qualitywater. Water quality can be determined through a labanalysis. This analysis will measure pH, electricalconductivity, cations (calcium, magnesium andsodium) and anions (carbonates, bicarbonates, sulfateand chloride).

Water pH. This indicator measures the generalmineral content of the water. Water pH levels usuallyrange from nearly 4.0 to 8.0 or higher. Below pH 7,the water is acid; above, the water is consideredalkaline. A pH of 7 is neutral. Water with pH levelsaround 8.5 or higher usually contains an excess ofbicarbonates which causes rapid increases in pH ofacid, sandy soils. Waters with acid pH levels containlower quantities of salts and are best for irrigatingblueberry plants. Alkaline water generally containstoo high a level of salts for blueberries.

Soluble salts. Dissolved salts are dissociated intoelectrically charged cations and anions. The commoncations include calcium (Ca), magnesium (Mg),sodium (Na) and potassium (K). The anions includebicarbonate (HCO

3) carbonate (CO

3), chloride (Cl)

and sulfate (SO4).

Terms used by laboratories in reporting thelevels of total dissolved salts (TDS) or cation andanions are: PPM - (1 part of salt per million parts ofwater or 1 milligram of salt per kilogram of solu-tion). Also, the content may be expressed as milli-gram per liter of solution which is the same as ppm.Grains per gallon (gpg) may be used if 1 gpg is equalto 17 ppm. Some laboratories may reportmilliequivalents per liter (me/1). One milliequivalent

is the equivalent weight of the element or compoundin grams per liter (1000 cc) of solution. For example,the equivalent of Ca = atomic weight divided byvalance or 40/2 = 20: therefore, 1 meg of Ca/l isequal to 20 ppm.

Electrical conductivity (EC). It is commonpractice for the salinity of water to be measured andreported as electrical conductivity (EC) inmillisiemens or milliohoms per centimeter (ms/cmor mmho/cm). In converting ms/cm to ppm, multi-ply by 640; thus 1.5 ms/cm x 640 = 960 ppm.

Sodium absorption ratio (SAR). Watercontaining high HCO

3 or CO

3 tends to increase the

soil pH. High sodium on soils containing clay canresult in very poor soil structure. The soil runstogether and is almost impervious to water. Somelaboratories report the Sodium Absorption Ratio(SAR), which indicates the relative activity of Na as itreacts with clay. The SAR is determined by thefollowing equation.

In most of Louisiana, a producer must beconcerned with both the Na and TDS (total dis-solved salts) in irrigation water. The suggested valuesin Table 1 are used to interpret the LSU samples.

Continued use of even low to medium levels ofTDS or Na in irrigation water can result in a saltbuildup that can become high enough to affect cropgrowth and yield adversely. A farmer should test hiswell for TDS and Na, and, if medium levels of eitherare detected, he should check his soils annually todetermine accumulation in the soil.

The following example may be helpful indetermining how much TDS and Na will be addedper acre foot of water.

An acre foot of water weighs 2.72 millionpounds. Therefore:

TDS ppm in water x 2.72 = TDS ppmper acre foot of water.

Na ppm in water x 2.72 = Na ppm peracre foot of water.

The factor for an acre inch of water is2.72/12 - 0.227.

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IrrigationIrrigation will increase blueberry yields and berry

size. It is very beneficial during the fruiting period,especially just before and during harvest. Irrigationshould be available with the first planting or trans-planting. It will eliminate plant loss caused by drysoils. Irrigation gives plants a good start and enhancesan earlier and larger harvest. Irrigation requires largevolumes of water and is a major capital investment.

Water RequirementsRainfall in Louisiana will normally average

about one-half to one inch per week during the berryfruiting period. In full production, blueberries require1.0 to 1.75 inches of water rainfall and irrigationwater per week or 0.14 to 0.25 inches per day. Adesign rate of 1.75 inches per week (7 days) is recom-mended for sprinkler irrigation. A design rate of 6gallons per tree per day is recommended for dripirrigation. Do not keep the root zone saturated all thetime. Irrigate each area about twice per week to avoida waterlogged soil. At each irrigation, provide enoughwater for a 3-1/2 day supply.

Sprinkler Irrigation SystemsTo determine the flow rate in gallons per

minute of water needed to sprinkle irrigate, usethis equation:

Where A = Acres irrigatedI = Inches of water appliedH = Hours of operation per dayD = Days of operation to apply I to A60 = Minutes per hour27,154 = gallons per acre-inchGPM = Gallons per minute

The pump must be able to deliver the waterflow rates (GPM) needed (see example 1 through 3or other desired rate) at about 60 PSI (pounds persquare inch) for most systems. The exact GPM andPSI are determined by designing for a particularorchard and irrigation requirements.

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Table 1. Estimated guidelines for interpreting laboratory data on water suitability for blueberry production.

Waterconstituents1 No problem Increasing problem Severe problem

Salinity1 less than more than Ec, dS/m (mmho/cm) 0.25 0.25 to 1.5 1.5 ppm 160 160 to 960 960SAR less than more than water 1.0 1.0 to 3.0 3.0Bicarbonates2 less than more than meg/liter 1.5 1.5 to 2.5 2.5 ppm 92 92 to 153 153Chlorides less than more than meg/liter 4.0 4.0 to10 10 ppm 142 142 to 355 355Boron less than more than(ppm or ug/g) 0.75 0.75 to 1.2 1.2

1Assumes that rainfall and extra water applied through normal irrigation will supply crop needs plus about 15 percent extra for salinitycontrol.2 Table estimates may need to be even lower because of the bicarbonate effect on pH of acid, sandy soils.

Example 1: Sprinkler Irrigation SystemsA = 1.0 acre, I = 1.75 inches, D = 7 days,H = 12 hours

GPM1, required for 1 acre: 9.4

GPM5, required for 5 acres: 47.0

GPM10

, required for 10 acres: 94.0GPM

15, required for 15 acres: 141.0

This system will provide a design rate of 1.75inches per acre every seven days operating 12 hoursper day. A maximum of 3.50 inches can be appliedevery seven days in this example by pumping 24hours per day instead of 12 hours per day. On theother hand, if 1.75 inches are adequate, then the flowrates required can be reduced by operating the systemmore hours per day and still apply the same amountof water. See example 2.

Example 2: Sprinkler Irrigation Systems(Recommended)A = 1.0 acre, I = 1.75 inches, D = 7 days,H = 18 hours

GPM1, required for 1 acre: 6.3

GPM5, required for 5 acres: 31.5

GPM10

, required for 10 acres: 63.0GPM

15, required for 15 acres: 94.3

This system will provide a design rate of 1.75inches per acre every seven days operating 18 hoursper day. Its maximum capability is 2.4 inches per acreevery seven days operating 24 hours per day.

Example 3: Sprinkler Irrigation Systems (Minimum)A = 1.0 acre, I = 1.0 inches, D = 7 days,H = 18 hours

GPM1, required for 1 acre: 3.6

GPM5, required for 5 acres: 18.0

GPM10

, required for 10 acres: 36.0GPM

15, required for 15 acres: 54.0

This system will provide a design rate of 1.0inches per acre every seven days operating 18 hoursper day. Its maximum capability is 1.3 inches per acreevery seven days operating 24 hours per day.

Drip Irrigation SystemsThe design rate for blueberries is based on 6

GPM per bush per day. Using 605 bushes per acre (6feet x 12 feet spacing) requires 3,630 gallons per dayper acre (6 x 605 = 3,630). The design pumping timeis 18 hours per day. To pump 3,630 gallons in 18hours requires a pump rate of 202 gallons per hour or3.36 GPM. From ponds or lakes, the minimumamount of water storage recommended is 1.5 acre-feet for each acre irrigated.

Operated for 18 hours per day, this systemapplies 6 gallons per bush to 605 bushes. If operated24 hours per day, it can apply 8 gallons per bush to605 bushes. Thus, this system can apply a maximumof 8 gallons per bush per 24 hours at a flow rate of3.36 GPM per acre. Two acres would be the sameexcept at a flow rate of 6.72 GPM per 2 acres. Fiveacres would have the same capabilities at 16.8 GPM.

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Table 2. Number of blueberries per acre* and GPM per acre to apply 6 gallons per bush operating 18 hours per day.

Spacing between rows Spacing within row

5' 6' 8'

10' 871 726 545

4.84 GPM/AC 4.03GPM/AC 3.03 GPM/AC

12' 726 605 454

4.03 GPM/AC 3.36 GPM/AC 2.52 GPM/AC

14' 622 519 389

3.46 GPM/AC 2.88 GPM/AC 2.16 GPM/AC

*One acre = 43,560 square feet

For newly planted bushes, use an average ofabout 0.25 gallon per day per bush; for half-grownbushes use about 3 gallons per day per bush; for full-grown bushes, use about 6 gallons per day per bush.Sample the root zone for excess wetness or excessdryness. Based on the soil moisture sample, adjust thequantity of water applied per day as needed.

Lateral lines are usually about 5/8 inch to 3/4inch in diameter. They are special material plasticliner (not regular polyethylene, P.E. pipe). Normallythey are 1,000 feet or less in length. The lateral is

14

Major materials for a blueberry sprinkler irrigation system with a 6 feet by 12 feet spacing.

Item Item Number required (Approximate) Costnumber name 1 Acre 5 Acres 10 Acres 15 Acres

4 20 40 60

35 175 350 525

39 195 390 585

39 195 390 585

39 195 390 585

39 195 390 585

32 160 320 480

7 35 70 105

1,500 7,500 15,000 22,500

6.3 31.5 63.0 94.3

50 50 60 60

usually placed on the soil surface near the base of thebushes and lengthwise the row. Emitters are installedon lateral drip lines according to bush spacing.Usually one emitter is used per bush. Its flow rate isusually 0.5, 1.0, 1.5 or 2.0 gallons per hour (GPH).For grown bushes, one emitter every other bushshould be adequate if the system is designed andoperated properly. To reduce emitter costs, use a rowtubing with holes about every 12 inches to 24 inches.This should work well for producing bushes, but itwastes some water on newly set plants.

1. Rainbird Impact SprinklerModel P3-PJ-07, 7/64 inchnozzle, inch male thread,25 PSI operating pressure

2. Rainbird Impact SprinklerModel P3-PJ-10, 5/32 inchnozzle, inch male thread,25 PSI operating pressure

3. Quick cut off valve 1/4inch female threads

4. PVC Adaptor, pipe toPVC, male thread byfemale socket,

5. Riser pipe, inch, plainends, 8 feet long

6. Stake, treated wood, 8 feetlong, riser support

7. Reducing tree, PVC, 3/4 x3/4 x socket

8. Reducing ell, 90 degreesPVC, 3/4 x socket

9. PVC pipe, Schedule 40,3/4 inch, lateral line

10. Water Source, GPM

Approximate PSI required

15

Major Materials for a blueberry drip irrigation system with a 6 feet by 12 feet spacing

Item Item Number required (Approximate) Costnumber name 1 Acre 5 Acres 10 Acres 15 Acres

1. Water source, GPM 3.36 16.8 33.6 50.4

Approximate PSI required 25 30 35 40

2. Cut off valve, No.: 1 1 1 1

Sizes: 3/4" 1" 1 2"

3. Water Meter No.: 1 1 1 1

Size: 5/8" 1" 1 1

4. Check Valve, No.: 1 1 1 1

Size: 3/4" 1" 1 2"

5. Pressure Regulator 1 3 3 3

6. Pressure Gauge 1 3 3 3

7. Chemical Injector 1 1 1 1

8. Filter 1 1 1 1

9. Water Treatment Unit 1 1 1 1

10. PVC, Supply Pipe 100 300 750 1,000

11. PVC, Tees 2 5 10 15

12. One GPH Emitters, NO.: 605 3,025 6,050 9,075

13. Lateral Line, feet: 3,630 18,150 36,300 54,450

14. End Plugs, Caps 24 60 120 180

15. Lateral, Tees 24 45 90 135

16. Valve 3 3 3 3

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One-acre Sprinkler Irrigation System

Specification: One acre, 192 inches x 228 inches (1.005 Acre). Each row 192 feet long, 32 plants spaced 6 feetapart. Rows are spaced approximately 36 inches apart from a triangular pattern. There are 12 sets. Each setconsists of three full circle sprinklers or up to six part circle sprinklers or a combination thereof.

Sprinkler

Wetted Pattern

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1. Water Source

2. Cut off Valve

3. Water Meter

4. Check Valve

5. PSI Regulator

6. PSI Gauge

7. Chmical Injector

8. Filter

9. Water Treatment

10. PVC Lines

One-acre Drip Irrigation System

Irrigating with Marginal Quality WaterRegardless of the irrigation method or rate,

blueberry plants irrigated with marginal quality waterwill grow and produce poorly. But, if plants arealready established on a site with marginal qualitywater, some of the harmful effect of salinity can bereduced by modifying the recommended irrigationpractices.

First, increase the irrigation rates at least 50percent. Second, fertilizer rates must be reduced andno fertilizer applied until 3 inches to 4 inches of rainhave occurred since the last application. This allowssalts from both the irrigation water and the previousfertilizer applications to leach out. Avoid fertilizingduring dry summer months.

If young plants are drip irrigated on lighttextured soils, use only one emitter per plant. Saltsfrom the water concentrate at the perimeter of thewetting pattern. With a single emitter per plant, thishighly concentrated salt zone moves away from themain root mass. With an emitter on each side of theplant, the salt zone concentrates at the center of theroot zone, and salt burn can occur. In heavier soils,this phenomenon is less pronounced because of awider wetting pattern and greater buffer capacity.

Research at Overton, Texas, indicates that whenmarginal quality water is used, better plant growthwas obtained with low volume spray emitters thanwith drip emitters. A heavy application of sawdustmulch also reduced salt damage. Better plant growthwas obtained in a clay loam than in a sandy loamwhen marginal quality water was used.

Weed ControlEffective weed control is probably the most

neglected aspect of commercial blueberry production.Most beginning producers fail to appreciate thenegative impact that weeds have on blueberry plants,particularly in early years.

Blueberry plants compete poorly for water andnutrients. Good weed control has to be an integralpart of a blueberry management plan. Blueberryplants have a shallow, delicate root system. Irreparabledamage may occur by allowing troublesome weeds tosurvive around blueberries even briefly.

Weeds may be controlled with either mechanicalor chemical management systems. Mechanical meansare by far the least cost-effective compared to chemi-cal systems. Mechanical weed control ranges fromhand hoeing to shallow cultivation with a rotary tilleror cultivator. Mechanical control is temporary, since itremoves only established weeds and does not preventre-establishment as do pre-emergence herbicides.

Chemical weed control is the most efficient wayto control weeds around blueberries. Two types ofherbicides should be used, post-emergence and pre-emergence. Post-emergence herbicides are applied tothe foliage of competing vegetation. Pre-emergenceherbicides are applied to the soil surface to preventweed seed germination or emergence. They are mosteffective when applied to a clean, weed-free soilsurface. Herbicides are often more effective whenused in combination to kill a broader spectrum ofweeds. Most herbicides work only on specific weeds.No single herbicide is effective on all weeds.

Weeds should be controlled around blueberriesin a band about 3 feet wide. Practice herbiciderotation, and use post-emergence following pre-emergence application to control escaping weeds inthe herbicide band. Sod can be maintained in themiddles and controlled by mowing.

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19

Blueberry Weed ControlTable 3.Rate/Acre Rate of Formulated Time WeedsActive Material for 1 Acre to Apply controlled RemarksIngredient Broadcast

oryzalin. Surflan 4AS Pre-emergence Annual grasses and2-0-4.0 lbs 2.0-4.0 qts broadleaf weeds

diuron Karmex 80W Pre-emergence Annual weeds1.2 to 1.6 lbs 1.5 - 2.0 lbs

simazineSpring Fall Princep 80W Pre-emergence Annual grasses and2.0 + 2.0 lbs 2.5 + 2.5 lbs broadleaf weeds

Princep 90 DG2.0 + 2.0 lbs 2.2 + 2.2 lbs

Princep 4G2.0 + 2.0 lbs 50.0 + 50.0 lbs

Princep 4L2.0 + 2.0 lbs 2.0 + 2.0 qts

Sim-trol 4L2.0 + 2.0 lbs 2.0 + 2.0 qts

terbacil Sinbar 80W Pre-emergence Annual weeds0. 5 - 1.0 lb 0.6 - 1.2 lbs

norflurazon Solicam 80 DF Pre-emergence Annual grasses,2.0-4.0 lbs 2.5-5.0 lbs some broadleaf

weeds, perennial weeds

napropamide Devrinol 50WP Pre-emergence Annual weeds4.0 lbs 8.0 lbs

Devrinol 10G4.0 lbs 40.0 lbs

DO NOT apply to establishedplants until soil has settled. Applybefore annual weeds emerge

Use only under plants established inthe field for 1 year. Repeattreatment in fall after harvest. DONOT use in soils with less than 2%organic matter.

Use a different herbicide in thespring to control a broader weedspectrum. DO NOT use ongravelly, sandy or loamy sand soils.DO NOT apply when fruit ispresent.

USE only under plants establishedfor 1 year. Apply in spring or afterharvest in the fall before weedsemerge but are less than 2 inchestall. Avoid contact of foliage andfruit with spray or mist.

Apply fall or early spring beforeweeds emerge. DO NOT apply onnewly established planting until soilhas settled. Apply once a year.

Apply to weed-free soil or fallbefore annual weeds emerge. Maybe used on newly planted andestablished plants until soil hassettled. Devrinol must be irrigatedin with sufficient water to wet soil2 inches to 4 inches within 24hours of treatment.

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Apply as a directed with 32 oz.nonionic surfactant/100 gals. ofspray solution. Apply as a coarsespray to avoid new shoots.

*Avoid drift contact with youngshoots, or severe injury will occur.

Apply to NON-BEARING bushesthat will not be harvested within 1year. Direct spray. DO NOTcontact blueberry foliage. Alwaysuse a crop oil concentrate or a non-ionic surfactant. Broadleaf weedsand nutsedge will not be controlledwith Fusilade.

Apply to NON-BEARING bushesnot harvested in 1 year. Directspray. Use flat nozzle tips. Alwaysuse a nonphytotoxic oilconcentrate. Broadleaf weeds andnutsedge will not be controlled.

Table 3. ContinuedRate/Acre Rate of Formulated Time to WeedsActive Material for 1 Acre to Apply controlled RemarksIngredient Broadcast

paraquat1 Paraquat + Plus Post-emergence Annual weedsWetting Agent2 lbs/gal

0.5 lb 1.0 qtGramoxone2 lbs/gal1.0 qt

fluazifop Fusilade 4E Post-emergence Annual weeds0.5 lb 1pt

Fusilade2000

0.25 lb 1 qt

sethoxydim Poast Post-emergence Annual weeds0.28-0.47 lb 1.5-2.5 pts

1Paraquat should be applied in a minimum of 40 gals./A. Paraquats effectiveness may be reduced if pond water is used.

Plant Nutrition*Blueberry plants require 13 mineral elements for

normal growth. The three used in largest quantitiesand most frequently needing replacement in soils arenitrogen, phosphorus and potassium. Calcium,magnesium and sulfur are considered secondarynutrients. They are used by the plant in largeamounts but usually require only periodic replace-ment in soils. The micronutrients of boron, iron,molybdenum, copper, manganese, zinc and chlorineare used in small amounts. Most soils contain suffi-cient micronutrients, so they are added only ifabnormal plant response (familiar symptoms) or asoil or leaf analysis indicates a deficiency. Somenutrients, such as boron, copper, manganese andsodium, can be toxic in high concentrations.

Foliar Nutrient Deficiency SymptomsNitrogen. Nitrogen deficiency is observed by

reduced growth, followed by older bottom leavesturning yellow-green. In more severe nitrogen defi-ciencies, the entire plant appears yellow-green. As thedeficiency progresses, new leaves turn red. Very smallnecrotic (dead) spots on the leaves may also be seen.Older leaves drop, and new leaves are considerablysmaller than healthy leaves. Young leaves will have adistinct pink color and turn pale green when growthceases. Symptoms of nitrogen deficiency are mostcommon in late summer and can be easily confusedwith water stress.

Phosphorus. Deficiencies in phosphorus are notas distinct as for other elements. Older leaves maybe dark purple-green. Young leaves are smaller andhave a purple cast. This coloration may be difficultto see except in bright sunlight. It is different fromthe reddening produced by a lack of nitrogen ormoisture.

Potassium. Potassium deficiency is indicated bysome interveinal chlorosis (yellow between veins) atthe tips of young leaves. Older leaves show the mostdistinct symptoms. They have scorched or dead spotson the leaf edges. The necrotic spotting may spreadover the whole leaf. Advanced potassium deficienciesresult in severe marginal scorching. As scorchingproceeds, the affected area curls upward.

Magnesium. Deficiencies in magnesium arecommon in blueberries. Interveinal leaf margins,most common on older bottom leaves, turn adistinct red. Interveinal marginal chlorosis mayprecede this red discoloration. The green areas thatremain on leaf veins have a distinct Christmas tree orV-shaped appearance. Leaves may cup inward. Oldleaves eventually drop off and leave long, bare stemsections. Symptoms are most prevalent in late sum-mer or on sandy soils.

Calcium. Calcium deficiency symptoms are noteasily recognizable. Young leaves and, to a lesserextent, older leaves may show marginal yellowing andscorching. Terminal leaves may have slight yellow-green blotches.

Sulfur. Symptoms of sulfur deficiency aresimilar to nitrogen deficiency except that the generalyellowing of the leaves is lighter and occurs onyounger leaves first. An almost completely bleachedor white-pink appearance on the entire leaf may beapparent on new growth. Older leaves usually remaingreen. Sulfur deficiencies are most common in deepacid sandy soils.

Boron. Shoot die-back is the most commonsymptom in boron-deficient blueberries. Terminalleaves are small, frequently misshapen and may bebluish. Slight yellowing or yellow spotting along leafmargins may be present.

Iron. Symptoms appear first on young leaves asan interveinal chlorosis. Veins and subveins stand outdistinctly like a green net over the entire leaf. Theyellowing may progress over the entire plant. Plantson soils with a pH higher than 5.5, excessive lime orphosphorus or waterlogged conditions are the mostlikely to become iron deficient.

Zinc. Like iron, zinc deficiencies includeinterveinal yellowing of younger leaves. It is distinctfrom iron in that leaves are small and the distancebetween leaves is shortened. Symptoms usuallyappear in the first part of the growing season andbecome less distinct in summer and fall.

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*Reprinted in part from: Patton, K., Texas BlueberryHandbook, 1987 production and marketing. Texas Agr.Extension Service/Texas Agr. Experiment Station, TexasA&M University, College Station, Texas.

Other nutrients. Manganese, copper andmolybdenum are usually not a problem unless thesoil pH goes below 4.0. Then manganese can becometoxic. Deficiency of copper or molybdenum couldalso occur. Plant symptoms for these elements areunclear.

Other common nutritionally related symp-toms. Any type of plant stress that ultimately dam-ages the root system, such as water stress, herbicidedamages, too much fertilizer, poor quality water orsoil pH less than 4.0, causes a multitude of plantsymptoms. Mild salt or fertilizer injury is indicatedby brown leaf spots, particularly around leaf marginsand on younger leaves. These appear one to five daysafter the fertilizer has been dissolved by rain orirrigation. Severe salt injury causes leaf drop and plantdeath. Low pH and salt damage also cause severeyellowing or bleaching of new leaves, tip die-back,small leaves, purple or red discoloration, and poor tono growth.

Plant symptom diagnosis. Once leaf symp-toms occur, the deficiency or toxicity is already severeenough to reduce growth and fruit production. It isbest to correct the nutritional problems before thesymptoms occur. Use leaf and soil analyses for thispurpose. Frequently, deficiencies of more than one

element at a time may occur. This causes compoundplant symptoms and makes it difficult to diagnoseelement deficiencies correctly in the field. Plant leafanalysis also helps in this situation. The ultimate testof any diagnosis is the plants recovery when treatedwith the deficient element in question.

Leaf analysis. Analysis of leaves for nutrientcontent can be useful in determining a fertilizationprogram. In general, leaf analysis is needed only everythree years. If a nutritional problem exists morefrequently, analysis may be required until the prob-lem is corrected.

To obtain meaningful results, pick leaves foranalysis from fruiting shoots during the last week ofharvest. Select the youngest full-sized (recentlymatured) leaves, generally the third to sixth from thetip of the shoot. Take five to seven leaves from eachof 10 to 15 bushes for each sample. Select bushes atrandom over the entire sample area. If possible, avoiddusty samples. For micro-element analysis, dont takeleaves sprayed with chemicals or nutrients.

Foliar nutrient levels for blueberries are in Table4. If a value for any particular element is in thedeficiency zone, modification may be necessary. Formicronutrient deficiencies, consider foliar sprayssuggested in Table 5.

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Table 4. Foliar nutrient levels of rabbiteye blueberries.

Deficiency Sufficient range ToxicityElement below minimum maximum level

Nitrogen (N) 1.2% 1.4% 1.8%Phosphorus (P) 0.09% 0.10% 0.20%Potassium (K) 0.35% 0.40% 0.60%Calcium (Ca) 0.10% 0.20% 0.40%Magnesium (Mg) 0.08% 0.15% 0.25%Sulfur (S) 0.10% 0.125% 0.20%Manganese (Mn) 23 ppm 50 ppm 350 ppm 500 ppmIron (Fe) 60 ppm 60 ppm 200 ppmZinc (Zn) 8 ppm 8 ppm 30 ppmCopper (Cu) 5 ppm 5 ppm 20 ppm 100 ppmBoron (B) 20 ppm 30 ppm 70 ppm 200 ppm

Fertilization ProgramNitrogen. The demand for nitrogen by

blueberries is relatively minor compared with its useby other crops. Nevertheless, nitrogen is the mostimportant element needed for blueberries. Sandy soilsused for growing blueberries are essentially void ofnitrogen. Nitrogen applied in the spring is quicklyleached out by heavy rains.

Because blueberries are sensitive to fertilizerburn, apply nitrogen only in several small applica-tions during the peak growing seasons of spring andfall. Avoid a single heavy application of nitrogen inthe spring. Do not make the last nitrogen applicationuntil sufficient rains have leached the previouslyaccumulated salts from the soil.

In addition to avoiding fertilizer injury bymaking only frequent small applications of nitrogen,it is critical that fertilizer of any sort never be appliedin a concentrated area at the base of the plant. Seriousroot damage and possible plant death will occur.Instead, uniformly sprinkle fertilizers around theouter base of the plant, extending at least one footpast the spread of the branches. Wait at least one totwo months before fertilizing newly set plants.

Blueberries are not only sensitive to the amountof nitrogen fertilizer but also to the type of nitrogen.Blueberries respond best to ammonium types ofnitrogen fertilizer. Avoid fertilizer containing nitratenitrogen. Urea nitrogen and organic forms of nitro-gen (cottonseed meal) convert to ammonium,making them acceptable nitrogen fertilizer sources.

All ammonium fertilizers, especially ammo-nium sulfate, have an acidic reaction with the soil.Continual use of ammonium sulfate in a sandy soilmay reduce the soil pH from 5.5 to 3.5 within oneto two years. With drip irrigation, this effect isaccentuated in the perimeter of the wetting front.The area next to the emitter may have a pH of 5.0,while the pH of the outer edge of the wetting frontwhere the ammonium sulfate accumulates may be3.5. Urea-nitrogen is less acid-forming than ammo-nium sulfate. If the soil pH is below 5, the urea formof nitrogen is preferred. If the soil pH is above 5,ammonium sulfate can be used. The soil pH aroundthe blueberry plant must be measured yearly. Lowsoil pH (less than 4.0) is one of the most frequentproblems in blueberry plantings.

For the first two to three growing seasons, themain objective of fertilizing is to obtain as muchgrowth as possible without fertilizer burn. Onceplants begin bearing, excessive vigor is not desirable,and plants do not need to be pushed with highnitrogen rates. The nitrogen fertilizer recommenda-tions for blueberries in Louisiana are in Table 6. Usethese rates only if plants are irrigated frequently withgood quality water. If youre unable to water at therecommended rate, reduce nitrogen rates by half.Two suggested options are listed with respect to thetype of fertilizer blend. If plants show typical nitro-gen deficiency symptoms and soil moisture is ad-equate, more nitrogen may still be needed.

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Table 5. Foliar sprays for correction of micronutrient deficiencies in blueberries.

Nutrient Material Rate/100 gal. Timing

B (Boron) Solubar 1.5 lbs. product Any time leaves are present.

Fe (Iron) Iron chelate Follow label instructions Apply to leaveswhen symptoms appear.

Mn (Manganese) Manganese chelate Follow label instructions Any time leaves are present.

Zn (Zinc) Zinc chelate 1-2 lbs. product 1 to 3 times during growing season.

Cu (Copper) Copper sulfate 1 lb. product Any time leaves are present.

Mo (Molybdenum) Sodium molybdate 1/4- 1/2 lb. product/acre Any time leaves are present.

A leaf analysis also helps detect an approachingnitrogen deficiency before it becomes serious enoughto cause deficiency symptoms. Dont give an extralarge catch up dose to small, stunted plants. It willdo more harm than good. Excessive growth causedby too much nitrogen also reduces yields. Reducenitrogen rates if excessive vigor on mature plantsoccurs. Its important to adjust the fertilizer ratebased on overall plant response.

Alternative fertilizer blends other than thosesuggested in Table 6 may be used as long as theoverall rates and an ammonium-nitrogen source areused. Excellent results have been obtained by usingslow-release nitrogen sources such as Nitro-form. If aslow-release nitrogen is applied, apply it less fre-quently.

Phosphorus and potassium. The fertilizerprogram in Table 6 should provide sufficient phos-phorus and potassium in most situations, but takeperiodic soil tests and leaf analyses to assure thatphosphorus and potassium needs are met. Table 7indicates the appropriate fertilization rates for differ-ent soil levels of phosphorus and potassium.

If soil tests and leaf analyses indicate thatmore phosphorus or potassium is needed, use themixed blend more frequently in place of just nitro-gen. For a phosphorus-only application, use 0-18-0(superphosphate). For a potassium-only applicationuse 0-0-52 (potassium sulfate) or 0-0-22 (potassium-magnesium-sulfate).

Other nutrients and pH. Magnesium deficien-cies frequently occur in blueberries. Use soil tests (lessthan 50 parts per million) and leaf analyses (less than0.08 percent) to determine if supplemental magne-sium is needed. In soils where there are eight parts ofcalcium to one part of magnesium, magnesiumdeficiency may also occur. If the soil pH is less than4.0, apply a very fine dolomitic limestone (500pounds per acre) to correct a magnesium deficiency.At soil pH higher than 4.0, apply potassium-magne-sium-sulfate or epsom salts in the spring. On matureplants, use 2 ounces per plant. On young plants, use1 ounce per plant.

For deficiencies of other major elements, checkwith the Extension Service for recommendations.Correct micronutrient deficiencies when confirmedwith a leaf analysis by using foliar application rates.

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Table 6. Blueberry fertilizer recommendations.Ounces per plant

12-12-12 Ammonium sulfate* or 15-5-10 aloneMarch April May September** March April May September**

Year 1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0

2 2.0 1.0 1.0 1.0 2.0 2.0 1.0 1.0

3 3.0 1.0 1.0 1.0 2.5 2.5 1.0 1.0

4 4.0 2.0 2.0 2.0 3.0 3.0 2.0 2.0

5 5.0 2.0 2.0 2.0 3.5 3.5 3.0 2.0

*Below pH 5, use urea as the nitrogen source. When using urea in place of ammonium sulfate, apply after as much as Table 6 rates.**Do not make the last fertilizer application until residual salts have been leached from the soil by 3 to 4 inches of rain or by sprinklerirrigation with water low in salts.

Table 7. Supplemental fertilization rate for phosphorus and potassium.

Potassium PhosphorusSoil test (ppm) Ounces of 0-0-52/plant Soil test(ppm) Ounces of 0-18-0/plant

40 very low 5 6 very low 6

90 low 3 12 low 8

150 medium Table 6 rate 22 medium Table 6 rate

One of the most critical nutritional problems inblueberries is correction of soil pH. Unless pH ishigher than 5.8-6.0, dont add sulfur. Improper sulfurapplication is a frequent cause of plant death inLouisiana. Sulfur acts like other fertilizer salts andkills the plant. If needed, apply only sulfur ratesrecommended by the soil testing lab. Never applyconcentrated sulfur in the zone at the base of theplant. Instead, broadcast uniformly around the plantextending past the perimeter of the branches. When-ever possible, make all sulfur applications six monthsto one year before planting.

Soil pH less than 3.5 to 4.0 presents a majorproblem on some sites with excess sulfur or ammo-nium sulfate. Lime applications are needed to correctthe problem. Normal doses of lime are detrimentalto blueberries. Instead, broadcast 1/3 to 1/2 poundper plant of a fine grade lime to the soil zone wherethe pH is low.

PruningFirst-year pruning. Bare-root plants should be

pruned back 25 percent to 30 percent when planted.This will compensate for root loss during diggingand transplanting. Container-grown plants need little,if any, pruning at planting, but any broke or damagedcanes should be removed. During the first growingseason, remove all flowers, particularly on weakplants. Fruit development will be at the expense ofvegetative growth. If flowers are left to develop,growth will be delayed proportionately. Removebranches that touch the ground. Cut back long,upright shoots to promote lateral branching.

Heavy fruit production on young blueberryplants will stunt plant growth and delay profitableproduction.

Second-, third- and fourth-year pruning.Pruning the second through fourth years consists ofremoving the lower twiggy growth and weakershoots during the dormant season. Some pruningwill be needed after harvest, too. Cut back all tallshoots by one-third so the plants can support thecrop the next season without excessive drooping.Remove all dead or damaged shoots.

Pruning mature plants. Once blueberry plantsattain the desired size, major pruning should be done

immediately after harvest. This allows for summerand fall regrowth. If the new growth is not toovigorous, some flower buds will form. In contrast,winter pruning removes more of the fruiting woodfor next year. If pruning is omitted on mature plants,they soon become tall, leggy and congested, resultingin diminished production. The fruiting mantle willbe exclusively on top and in the outer canopy. Mostof the plants volume will be occupied by unproduc-tive wood.

Berry size is often reduced and ripening delayedwhen plants are left unpruned. It is important toprune blueberries to generate more young wood forfruiting. Older stems more than one inch in diametergenerally have poor production and should be re-moved. When a bush develops too many canes (15 to20), the depth of the fruiting surface is only 6 - 12inches, whereas if the bush has about 10 canes, thefruiting surface extends several feet into the bush.Fruit size and earliness are increased.

Pruning for mechanical harvesting. Plants tobe harvested mechanically should have a base of only8 inches to14 inches. Wider-based plants will notallow the catch on the harvester to close enough toprevent fruit loss during harvest. Plants should bepruned, beginning at an early age, to develop anarrow base. Its not necessary to remove suckers orcanes that grow between plants in the row. Theseonly hasten the development of a complete hedgerow.

MulchingAdvantages. Applying an organic mulch 3

inches to 4 inches thick around plants can be animportant maintenance procedure for small (less than1 acre) blueberry plantings. A mulch such as sawdust,pinestraw, straw or hay has many benefits. Theseinclude maintenance of soil surface moisture, sup-pression of weeds, improving soil structure and rootgrowth, moderating soil temperature, erosion reduc-tion and enhanced spreading of a drip emitter wettingpattern. Mulches also tend to reduce potential dam-age caused by poor quality water. Some benefits ofmulch are offset by potential disadvantages, however.

Disadvantages. Mulch can be cost prohibitivefor a large acreage. Even if the mulch is free and easily

25

accessible, spreading cost, unless mechanized with afront end loader and a mechanical spreader, can beseveral hundred dollars per acre. This may be a yearlycost, because most mulch lasts only a year or two,and repeat applications are needed. Other negativeaspects of mulch include the increase in fire ant andmice populations. Both can be difficult to controlonce a planting is infested.

Some mulches cause more weed problems thanthey prevent. Hay mulch, for example, may infest aclean field with many unwanted weed seeds. Themulch must be weed free. Most mulches have lownitrogen. Soil microorganisms rob fertilizer and soilnitrogen to decompose the mulch. Nitrogen defi-ciency on heavily mulched fields can occur. Increasenitrogen rates if a thick, low nitrogen mulch, such assawdust, is used. If the mulch becomes dry, it may bea fire hazard.

An initial one-time mulch may suffice becausebenefits from mulch are apparent the first few yearsof the planting when prevention of water stress andweed competition is most critical. For this purpose, afresh sawdust mulch is probably the most easilyobtainable and trouble free. If mature blueberryplants have ample water during dry summer months,mulching is usually not required.

Cultivar SelectionBlueberry varieties for commercial plantings

should be selected on size, firmness, ripening datesand stem scar. In non-PYO plantings, adaptability tomechanical harvest and shipping quality may beimportant.

Ripening is critical, especially when marketingPYO. Berries ripening over as long a period as pos-sible will attract and hold customers. Early ripeningvarieties generally command the best prices. Thesevarieties need to be a major portion of the orchardwhen berries are to be shipped to other areas. Earlyripening rabbiteye varieties begin ripening in earlyJune (south Louisiana) and mid June (north Louisi-ana). Mid-season varieties usually begin ripening inlate June and early July. Late season varieties ripen inearly to mid July. Most varieties ripen over a three- tofour- week period.

The type of stem scar determines, to a largedegree, how well a variety can be held and shippedwithout developing postharvest quality problems. Awet scar variety will bleed and deteriorate rapidly. Dryscar varieties are much more suitable for mechanicalharvesting and shipping fresh.

Fruit quality involves several characteristics: size,color and flavor. Large fruit has more sales appeal,particularly for PYO. The larger fruit is easier toharvest and will take fewer to fill a pint. Smaller fruitis well suited for processing markets. Varieties withlight-colored fruit with a heavy wax bloom arepreferred over dark, shiny fruit. Flavor is a product ofthe sugar/acid ratio. When the fruit is allowed toreach maximum maturity on the plant with maxi-mum flavor enhancement, most varieties are equal orindistinguishable from one another in terms of flavor.

As with all fruits, for best postharvest quality,cool fruit to near 32 degrees F as soon as possibleafter harvest. This is imperative for fruit destined forfresh markets.

PollinatorsCross-pollination is an absolute requirement forrabbiteye blueberries. They will set little fruit ifplanted in solid blocks. Besides increased fruit set,cross-pollination results in bigger fruit and earlierripening.

The new southern (or low chill) tetraploidhigh bush blueberries are self-fruitful, but theyllbenefit from cross-pollination by yielding larger,earlier fruit.

The most efficient pollinator of blueberries isthe southeast blueberry bee, a solitary native bee.Bumblebees are effective pollinators, too. While lesseffective, honeybees can be brought into the orchardin sufficient numbers during flowering to ensuregood cross-pollination.

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27

Table 8. Blueberry CultivarsType1 Pollinating2 Area La.3 Ripening4 Fruit Market5

Variety* of cultivar Type Recomm. Date Quality Type Comments

Avonblue SH A N&S Early May Good PYO

& Fresh

Aliceblue R B N&S Late May Good PYO& Fresh

Beckyblue* R B N&S Late May Excellent PYO, FreshDry Scar & Process

Bluegem* R B&C N&S Early June Good Early PYO,Fresh

Bonitablue* R B&C N&S Late May Excellent Early PYO,Fresh &Process

Brightwell R C&D N&S Early June Good PYO & FreshDry Scar

Briteblue* R D N&S Mid June Fair Dry PYO &Scar Fresh

Chaucer R B N&S Late May Fair PYO &Process

Choice R D N&S Late June Good PYO &Process

Climax* R B&C N&S Late May Good PYO, FreshDry Scar Process

Delite* R D N&S Late June Fair to Late PYO,Good Dry Fresh &Scar Process

Floridablue SH A N&S Late April V. Good Early PYO, Fresh

Georgiagem SH A N&S Early May Good Early fresh

Large fruit, adapted tomech. harvest. Flavormild and acid.

Large fruit, can beharvested mech. Flavorsweet and aromatic.

Large fruit, goodornamental, leadingcultivar in N. Fla., berryfirm & stores well.

Bush susceptible toPhytophthora c., largefruit, plant in welldrainedlocation on elevated rows,high consistent yielder.

Fruit large, berry storeswell, firm, no fruit scar,leading variety in Fla.

Firm berry with little orno fruit scar, recom-mended for trial plan-tings only, fruit large.

Fruit quality fair, berriestend to be stemmy.Not recommended.Fruit large.

Fruit tends to tear whenpicked, leaving scar. Notrecommended except asornamental.

Small berry, should beharvested mechanically,best ornamental variety.

Leading pollinatingcultivar, can be mech.harvested, large fruit.

This cultivar beingreplaced by newercultivars, fruit medium.

Plants not vigorous,ornamental useprimarily, large fruit.

Medium fruit, littleinformation available onthis cultivar, trialplantings only.

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Table 8. ContinuedType1 Pollinating2 Area La.3 Ripening4 Fruit Market5

Variety* of cultivar Type Recomm. Date Quality Type Comments

Powderblue* R D N&S Late June V. Good Late PYO,Fresh &Process

Premier* R C&D N&S Late May V. Good PYO, FreshDry Scar & Process

Sharpblue* SH A N&S Late April Fair to Early PYO,Good Fresh

Southland R D N&S Late June Fair PYO &Dry Scar Process

Sunshine SH A N&S Early May Good FreshBlue

Tifblue* R D N&S Mid June Good Late PYO,Dry Scar Fresh &

Process

Woodard R C N&S Early June Fair to PYO, ProcessPoor

Cooper SH A S Early May Good PYO & Fresh Trial plantings only.

Gulfcrest SH A S Early May Good PYO & Fresh Trial plantings only.

ONeal SH A A Early May Excellent PYO & Fresh Trial plantings only.

Blue Ridge SH A S Early May Excellent PYO & Fresh Trial plantings only.

Cape Fear SH A S Mid May Fair PYO & Fresh Trail plantings only.

Fruit is attractive, goodpollinator for Tifblue,large fruit.

Fruit stores well, will fruitw/o pollinator, but neverplant w/o pollinator forbest results, large fruit.

Number one Southernhighbush planted in Fla.Trial plantings only inLa., fruit large.

Being replaced by othercommercial cultivars.Ornamental use prima-rily, medium fruit size.

Ornamental use. Good,vigorous plants, berriesfirm, store well, trial plan-tings only, medium fruit.

The leading variety inthe South. High yieldingdependable producer,fruit large.

Ornamental use good,small plants, beingreplaced by newercultivars, large fruit.

* Recommended for commercial plantings.1 SH Southern Highbush Cultivar R Rabbiteye cultivar2 A Early blooming southern high bush self-pollinating. May be

planted alone or with any other cultivar. Best to plant twocultivars for maximum yield.

B Early blooming Rabbiteyes. Plant early blooming Rabbiteyetypes together to ensure the best pollination.

C Mid-season blooming Rabbiteyes. Plant together to ensurethe best pollination.

D Late blooming Rabbiteyes. Plant together to ensure the bestpollination.

B, C and D: All require cross pollination. Plant two or morecultivars from the same letter group. Cultivars marked withtwo letters such as B and C may be planted with A, B or Ccultivars.

3 N North Louisiana S South Louisiana4 Ripening dates for south Louisiana.5 PYO Pick your own Fresh Fresh market, stores well Process Short storage

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PropagationRabbiteye blueberry plants are propagated

suckers or off shoots by budding on native rootstockand by rooting softwood or hardwood cuttings.

Softwood cuttings The most commoncommercial method of propagating rabbiteye blue-berries is placing softwood cuttings under mist inprepared media. Softwood cuttings can be takenthroughout the growing season, but highest rootingpercentages are obtained from cuttings taken soonafter the first flush of growth in the spring. Manycuttings can be taken at this time because mostshoots are in the same stage of growth.

Cuttings that are too tender and succulentshould be avoided to reduce breakage and wilting.Cuttings that have passed the first period of growthand are beginning to harden are the most desirable.Terminal cuttings 4 inches long with all but two orthree leaves removed give good rooting results.Cuttings taken from matured growth require longerto root, and lower percentages of rooting usuallyare obtained.

Various media are satisfactory for rootingblueberries. Good rooting percentages have beenobtained with coarse sand, pine bark, perlite, sawdustand peat. Root development usually is best in mediacontaining 25 percent to 50 percent peat. Peat andperlite (1:1); peat and sand (1:1); peat, bark and sand(1:1:1); peat, sand and sawdust (1:1:1 and 2:1:1)have proved successful in most rooting trials. Lessroot development is present in a coarse sand mediumthan in mixtures of sand and peat.

Rooting beds are best under shade (30 percentto 60 percent shade) to reduce desiccation of cuttingsby lowering daytime temperature and light intensity.Intermittent mist watering is desirable for rootingsoftwood cuttings. A system based either on rate ofevaporation or time can be used.

Most research indicates that hormones are notbeneficial in rooting rabbiteye blueberries.

Hardwood cuttings Hardwood cuttings aretaken during the winter (dormant period) fromstrong, healthy shoots of the past seasons growth.Shoots from which cuttings are taken, called whips,are commonly 12 to 36 inches long. Whips are

usually present on vigorously growing rabbiteyeblueberries, but whip formation is stimulated bysevere pruning in the dormant season.

Whips are produced commercially by cuttingplants back to lengths that are 6 to 12 inches less thanthey were before the previous seasons growth.Hardwood cuttings are collected after sufficientwinter chilling has occurred, usually in late Januarythrough February, and before bud growth begins.Cuttings (whips) can be collected earlier and stored at35 to 40 degrees F in moist spagnum moss withadequate ventilation until placed in beds.

Whips are divided into cuttings of the desiredlength (about 5 inches). Cuttings can be made with asharp knife or bench saw. Pruning shears usuallyinjure cuttings unless the shears have been adapted forthis purpose. A bench saw with a fine blade is usedcommercially to cut large quantities of whips to thedesired length simultaneously.

Open beds under a lath house with mediasimilar to those used with softwood cuttings (peatand sand, 1:1; peat and perlite, 1:1) are satisfactory.Cuttings are inserted into the medium from one-halfto two-thirds of their length. The medium should bepressed firmly around the base of the cuttings.Spacing of cuttings usually is 2 x 2 inches.

Propagating beds must be kept moist, but guardagainst using too much water. The critical time isafter the cuttings are in leaf but before rooting hasoccurred. Mist watering can be used but is not asessential as with softwood cuttings.

Plants can be fertilized weekly after cuttings arerooted and established (usually by May or June). Awater-soluble complete fertilizer (1/2 oz. per gal. ofwater) is used. Plants can be grown in the propaga-tion bed until winter and then transplanted into anursery or into containers. Good results have beenobtained by transplanting rooted hardwood cuttingsinto 1-gallon containers in late July. Such plants areplaced under 50 percent shade and watered frequentlyfor two to three weeks before fertilizing each potwith 1 to 2 oz. of a slow-release fertilizer (Osmocote14-14-14). Plants then are watered as required.Sufficient growth often is obtained to permit fieldplanting or sale as container plants in winter.

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Other propagation methods Suckers growfrom roots a distance of a few inches to several feetfrom the parent plant. These can be separated fromthe main root system with fibrous roots intact.Excessive mulching usually increases suckering andpromotes a shallower root system that makes separa-tion of rooted suckers from the main plant easier.Suckers should be pruned back heavily, transplantedto a nursery (or potted in a 3- to 5-gallon container)and grown for a year before setting in their perma-nent location.

Insect Identification and Control

Cranberry Fruitworm(Acrobasis vaccinii Riley)

This small worm is a pest of cranberries andmany species of wild and cultivated blueberries. Thelarva at maturity is about 1 inch long. The head isyellow with light brown markings. The body isyellow-green but may have a slight red tinge.

The adult is a small, mostly gray, moth which isseldom seen because it flies at night. The mothsemerge from pupae that overwinter in the soil duringlate March and April. The eggs are laid, for the mostpart, within the calyx cup of the green berries. Thehatching larvae crawl about the fruit and usually enterthe berry at the junction of the stem and fruit.

As the larvae develop, they move about fromone berry to another within the fruit cluster. Eachlarva remains concealed within the fruit cluster whilefeeding. A single larva may destroy three to six berriesin a cluster. Infested berries become filled with frass,turn blue prematurely and shrivel. The cluster ofberries is usually webbed together, and small pocketsof frass may extrude from the entrance holes. Thefrass appears to clump around the entrance because ofthe silk webbing. Damaged fruit is sometimesharvested with the good fruit because of the webbing.By mid to late May, larval development is complete,and they leave the berries and fall to the soil. Herethey pupate and remain until the next spring. Insome cases, a small percentage may emerge andproduce a small generation on another host.

Controls for curculio will also control this pest.

Cranberry Rootworm(Rhabdopterus picipes Oliver)

This small leaf-feeding beetle can make thefoliage look tagged, but the larval feeding on rootscan cause yellowing and occasionally kill small plants.

The adult beetles are about 1/4 inch long andshiny brown. They emerge in May through June andfeed on the foliage of blueberries, camellias andazaleas. Eggs are laid in the soil about the base ofplants. The larva are six-legged, white and c-shapedwith a light brown head and are about 1 inch long atmaturity. They feed until fall and then hibernate aspartly grown larvae. Feeding is completed in thespring with adult emergence in May.

Infested plants are not fruitful. They are paleyellow, and the leaves turn red and fall prematurelyin the fall. Occasionally, in extreme cases, the plantmay die.

Sevin gives good control of the adults whensprayed late in the afternoon. No control has beenfound for the larvae in planted fields.

Stem Borer (Oberea myops)This small long-horned beetle

attacks and infests wild and culti-vated blueberries, azaleas, rhododen-dron and laurel.

The adults of the stem borerare present during peak growingtime. Eggs are inserted under a flapof bark near the terminal of a cane.Usually new growth or shoots arechosen for egg deposition. The larva,on hatching, tunnels upward, killing

the terminal. It then reverses direction and boresdownward. Two to 10 inches may be tunneled thefirst year. Small lateral tunnels to the outside aremade periodically to remove the excess frass andchewed stem.

In winter, the larvae are inactive. The nextspring, feeding resumes and, after several months,reaches the crown. Cold weather again deactivates thelarvae. Feeding resumes in the spring of the third year,and the galleries are enlarged. Several canes may beencompassed. Another winter of inactivity follows,and the larvae pupate the following spring and adultsemerge to continue the cycle.

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The larvae are smooth, legless, elongate wormsabout 1/8 to 1 1/4 inches long. The head is brownand the legs creamy-white. The adult is light brown,elongate and has long antennae.

Damage may be observed as terminal die-back,cane death or by the mounds of frass at the base ofplants during the summer. Remove infested caneswhen found or during pruning time.

Blueberry Maggot(Rhagoletis menday Curran)

Blueberry maggots overwinter in puparia in thesoil. As the soil warms in the springs, the adultsemerge. After one week, female flies actively seek largegreen, nearly ripe or ripe berries and deposit one toseveral eggs under the skin of the fruit. Hatchingoccurs in five days, the young larvae feeding just underthe skin. Large larvae tunnel throughout the fruit.Larvae mature in 18 days and drop to the ground topupate. Only one generation occurs every year.

Larvae are white or gray-white and maggot-like.The head is pointed, indistinct and very small withblack mouth hoods. The body is tapered.

The adult flies are about 3/16 inch long. Thecharacteristic feature is the broad black banding of thewings. The tip of the thorax is white or pale, and theabdomen is striped.

Blueberry Bud Mite(Acalitus vaccinii Keifer)

This mite is common on both wild and culti-vated blueberries. No variety is immune to attack.

The mite is white, translucent and elongate withfour short legs. Its presence is established by lookingfor injury rather than the mite itself. The mite feeds onthe bud scales and on developing leaf and floral partswithin the bud. Parts fed on become roughened andwarty, usually with red discoloration. Occasionally,small red pimples may occur on the fruit. Persistentfeeding by high populations of mites can kill planttissue and cause failure of buds to expand and produceflowers, thereby reducing fruit yield. Injury occursshortly after the mites enter the new buds. Criticaldamage occurs as early as late summer or early fall.

Mites spend most of their life in the buds ofblueberry plants. In the spring, the mites migratefrom injured tissue to the outer scales of newlyforming buds. They crawl under the scales, feed,

mate and lay eggs. As the population increases, themites move to the center of the bud. Feeding, mat-ing, egg laying and populations increase throughoutthe fall and winter.

Control is obtained by two applications of amiticide made in July and August. Since mites are inthe bud scales, sprays must be applied with highpressure (200 psi) to penetrate the buds. Goodcoverage may require up to 400 gallons per acre,depending on plant size. Pruning of old canes alsohelps reduce mite populations.

Scales (Coccids)Several species of scales have been reported on

blueberries throughout their range. Those that occurin Louisiana are: 1) Japanese wax scale (Ceroplastesceriferus (Fab.) - one generation -approximately 400-3,000 eggs, feeds on stem and fruit, seldom onleaves. 2) Terrapin scale (Lecanium nigrofasciatumPergrande) - one generation a year - bears live young,overwinters as fertile third instar, mature in spring,young settle on foliage, third instar migrates to stems,male develops on leaves, emerges mates with femalethat overwinters. 3) Oystershell scale (Lepidosaphesulmi Linnaeus - armored scale, multiple generations,80-100 eggs per generation, infest only stems. Shellcovering looks like oyster shell, hence the name. 4)Putnam scale (Diaspidiotus ancylus Putnam), multiplegenerations, primarily on stems under bark scale, wellcamouflaged. Can be found on fruit and leaves, onfruit as circular gray spots surrounded by red discol-oration - harm product salability. 5) Cottony maplescale (Pulvanaria innumerabilis Rathvon) - overwin-ters as young female on stems. Matures in spring.Produces egg sack in early May. Eggs hatch late Mayor early June. Nymphs settle on underside of foliage.In fall, migrate back to stems. Males develop onleaves, emerge in early fall, mate and die, 6) Europeanfruit Lecanium (Lecanium corni Bouche) - overwintersecond nymphal instar on branches. Mature earlyspring. Eggs laid in late April or early May. Hatch inlate May or June. Migrate to leaves, develop untilfall. Migrate back to stem - one generation.

Japa

nese

wax

scal

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Oys

ters

hell

scal

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All coccids have piercing, sucking mouthparts.All but wax scale may be unnoticed until populationsare very high and some damage has occurred. Thosewith multiple generations can cause severe problemsin one year. Those with single generations are not asdamaging. All are easiest to control in the immaturestages shortly after emergence from beneath the oldfemale. Most materials are effective on the crawlers.As they mature, they become harder to kill.

Plum Curculio(Conotrachelus nenuphar Herbst)

This snout beetle or weevil isprimarily a pest of peaches, plums,apples, cherries, other stone fruitsand blueberries.

The adult weevil is 1/4 inchlong and has a snout. The bodysurface (forewings) is warty anduneven. The curculio is brown withpatches of white or gray. The adults

overwinter under trash or in wooded areas adjacent toberry fields. They begin emerging during the end ofbloom or at berry set and emerge for four to sixweeks. The adults feed on the petals of the blossomand then begin feeding on the green fruit. Eggs aredeposited within the green berries in shallow c-shapedfeeding scars. Eggs are usually laid singly. Their larvae,upon hatching, feed on the interior of the berry. Thiscauses the berry to stop developing and fall to theground. The larvae at maturity leave the empty hulland enter the soil to pupate. In about three weeks,the adults emerge. If fruit is present, a second genera-tion develops in the fruit. Although only a single eggis laid per fruit, each female can lay about 140 eggs.

Sprays should be timed at the end of bloom anda