Land preparation• Utilize the stale seed
bed technique to reduce weeds
• Plow or chisel if necessary (depth: 30 cm)
• Rotary harrow with horizontal axis before hilling (depth: 15 cm)
• If necessary to dry the soil: tooth harrow
Fertilization• Apply 60 lbs/acre of
phosphorus fertilizer• Apply 50 lbs/acre of
nitrogen fertilizer• Apply 55 lbs/acre of
potassium fertilizerPests
Flies • Install traps
Planting• Optimal sowing dates
vary with locality, soil type and variety: follow production guidelines
• Onions may be direct sown or transplanted.Where direct sown:• Sow at 25 mm
depth• 30 to 40 cm
between rowsPests
• Apply preventative pest spray for ants, cut worms and nematodes
Onion fly• Create a buffer zone
‘Green Banner’ on the edgeofthefields
Seedling fly• Foliar treatments as
recommendedDiseases
• Fungi and bacteria are predominant
• Use clean water and good crop moisture control
• Sow on warm soil
Weeding• Apply a herbicide if
necessary• Hand weeding best al-
ternative to herbicide application
Diseases Botrytis
• Install spore sensorsInsects Gray worm
• Begin to screen for presence
Onion and seedling fly:• Begin to screen for
damage
Weeding• 1st mechanical
weeding when the onion has 2 leaves
Fertilization• Apply fertilizer: 20
lbs./acre of phospho-rus; 70 lbs./acre of nitrogen; 80 lbs./acre of potassium
• Apply sulphur in the form of ammonium sulphate
• Apply a foliar spray with B, Mg, Mn, & Zn
Diseases• Apply fungicides &
herbicides Botrytis• Continue screening• Start preventive
treatmentfromfirstspot appearance
Insects Gray worm
• Continue screening; if necessary, treat in the evening
Onion and seedling fly:• If damage > 5 to 10
%, apply required foliar insecticides
• Mow the edges of fields
FertilizationStage 3 leaves:• Apply 20 lbs./acre of
nitrogen fertilizer• Apply 25 lbs./acre of
potassium fertilizer• Add calcium (Ca),
sulfur (S) and manga-nese (Mg) as needed (ifdeficientinthesecompounds) via foliar spraying
Weeding• 2nd mechanical
or hand weeding between rows if necessary
Insects • Apply herbicides,
fungicides, and surfactant at recom-mended rates
Thrips• Start screening• If treatment needed,
use nozzles with brush jet or double brush - volume of water > 500 L/ha
• Take advantage of the dew
Disease• Continue screening
Weeding• Weed control is vital,
especially in early growth stages
• Manual weeding as required
Irrigation• Irrigate as needed
Insects• Continue daily
screeningDisease
• Continue daily screening
Irrigation• Increase irrigation (peak
water demand at this stage of the crop)
Weeding• Weeding as required
InsectsThrips, Leaf Minors and Beet Army worms• Scout, use pheromone
traps, hand picking• Integrated Pest Man-
agement (IPM)• Pesticides as last resort
Disease• Screenfielddailyfor
pest and diseaseBotrytis• Screening; the thresh-
old: 3 lesions on old leaves and 1 on young leaves
• Adjust the amount of slurry at the culture stage
• If prolonged rain, use systemic fungicides
Downy mildew• Interveneinfieldand
neighboringfieldsiffirstsymptoms appear
Bacterial rot• Limit sprinkler irrigation• Apply preventative pest
sprays as required
• Avoid activities that may damage bulbs
• DO NOT mold up bulbs
Irrigation• Reduce irrigation; only
irrigate as neededFertilization
• Application at this stage to the discretion of the producer
• Avoid applying nitrogen fertilizers as it affects bulb quality at storage
Weeding• Weed control not
necessary at this stage and onwards as emerging weeds will not affect yield
• Continuefieldsanita-tion as needed
Insects• Continue daily
screeningDisease
• Continue daily screening
Irrigation• Cease irrigation 7
days prior to harvestHarvest screening
• Mature onion tops begin to fall and dry (> 50%); When more than 50% of the sheaves fall (“break-neck is observed”), the crop can be harvested
• Maximum yield is attained when tops are completely down and dry
• Yields may increase 25 to 30% between the stage when tops begin to go down, and the leaves are fully down and dry
• Optimum time for harvest must be a balance between highest yields and reduced bulb storage quality, if there is any intent to store rather than immediately sell the onions
Harvest • Lift onions carefully
by hand• Cut the leaves at + 2
cm from the neckDrying
• Leaveinfieldfor3-7days to be dried by the sun (minimum 2 days if weather allows)
• Once dry, attach in packs of 6 to 8 or windrow onion in thefield
• Alternatively, onions can be placed in a commercial dryer for at least 3 days
Curing• Cure onions for 1-2
weeks in a shaded, well-ventilated place before storage
Field management • Abandonedfields
must be harvested and immediately buried. Caution: if Frontier Herbicide has been applied, do not revert to onion, green onion, celery or carrot
Sorting and Grading• Sort harvested crop
for quality, removing diseased or damaged pieces
• Grade onions in view of different market needs prior to storage (e.g. high value market, export, agroprocessing, etc)
Storage• Store onions in a cool,
dry area• Onions can be stored
up to 4 months under the appropriate conditions
Diseases• Onions should be
inspected periodically for deteriorated bulbs
ONIONSSite Selection
• Flat terrain, good drainage, resistant to erosion, not prone to weed infestation
• While all types of soil are suitable, sandy loam soil types yield best results
Soil Type• SoilpHshouldnotbeacidic(lessthanpH6);fine,
loose soil tilth; free from stones, trash and weeds• If the soil is compact, use excavator at 45°
Choice of cultivar• Consider market demand, soil type, climate con-
ditions (e.g. photoperiodicity: short-day onions recommended in Caribbean), equipment, irrigation capacity
• Choosenew,certifiedseed• Saturn, 10210, and Mikado are recommended va-
rietiesRotation
• A 3 to 5 year rotation recommended to reduce the buildup of pathogens
• Avoid same family plants as previous crops (e.g. escallion)
• Consider onion companion planting (group of crops growntogether)forbeneficialplantinteraction
• Foe crops: asparagus, beans, peas, sage• Friendly crops: beets, brassica family, carrot, cham-
omile, cucumber, dill, leeks, pepper, potato, roses, spinach, squash, strawberry, summer savory, to-mato
Planting Schedule• Best results are observed by planting September to
January so as to avoid harvesting in the wet season (June to October)
Irrigation Requirements• Approx. 18,000 gallons/acre at germination (weeks
1-2); 30,000 gallons/acre per week during vegeta-tive development (weeks 3-11); 42,000/acre gallons per week at bulb initiation (weeks 12-13); 35,000 gallons per week (weeks 14-16) during bulbing
• Irrigation should be discontinued 1 week before harvesting
Fertilization & Other Inputs• Should be based on the results of a soil test, the
needs of the crop, the soil type, climate conditions,
and available fertilizers (NPK)• Important secondary and micro-nutrients include S,
Mn, Cu, Mo• Avoid applying nitrogen fertilizers after bulbing to
ensure good shelf-life of produce• Do consider the 4R’s of nutrient management: right
source, right rate, right time, and right place• Input list should include seeds, pesticides,
fungicides, herbicides, and fertilizers. Read product instructions carefully; products should be applied at the recommended rates
TECHNICAL ITINERARY
LAND PREPARATION PLANTING GERMINATION 1-3 LEAVES 3-5 LEAVES 5-7 LEAVES BULB INITIATION BULBING BULB MATURATION HARVEST/CURING POST-HARVEST
LEGENDSPESTS
WEEDS
DISEASE
TOOLS
SCREENING
Consult your local Extension Officer for further details on crop
production.
GENERAL GUIDELINES