Using Herbicides in Pine and Hardwood Management

Kyle CunninghamAssistant Professor of Forestry

Forest Regions in Arkansas

Uplands

Bottomlands

Pine-Hardwood

Mixed, 17%

Bottomland Hardwood,

16%Upland

Hardwood, 39%

Pine, 27%

Vegetative Competition

• Serious competitor to crop trees• Competes for sunlight• Competes for soil water and nutrients• Competes for growing space• Can cause a reduction in growth and

survival

Competition Sources• Common grasses

– Bermuda grass– Bahiagrass– Johnson grass– Fescue– Broomsedge

• Woody species– Persimmon– Blackgum– Sweetgum– Ash– Hickory– Sumac

• Broadleaf weeds– Fireweed– Goldenrod– Curly dock– Horsetail– Ragweed– Smartweed– Pigweed

• Vines– Trumpet creeper– Poison Ivy– Virginia creeper

Options for Competition Control

• Hand weeding• Chainsaw• Shearing• Chopping • Discing• Herbicides

“Just say NO”

• Hand weeding • Chainsaw• Shearing• Chopping• Discing

Importance of Herbicides

Useful on all terrainEase of applicationQuickEconomical vs. mechanical operationsLow disturbance to a forest site

Leaves vegetation and litter

Considerations Prior to Application Crop species Primary competitors Application types Timing concerns Environmental factors Sensitive areas READ THE LABEL!!!!!!!!

Banded versus Broadcast

Pines

• Loblolly• Shortleaf

Herbicide Use

• Site prep• Herbaceous weed control • Woody release• Mid-rotation brush control

Site Prep

• Imazapyr + glyphosate = “Gold standard”• Cost-efficacy is the driving determinant• Rates vary with the species complex on a

site• Triclopyr is used when waxy-leaf species

are a problem• Rates also vary by pine species• Use a nonionic surfactant (NIS) or

methylated seed oil (MSO)– % v/v

Site prep

• Shortleaf = imazapyr + glyphosate• use same materials and rates as for

loblolly, but complete all applications in August-September and plant seedlings in January-February

• If using Velpar L– 4-6 qts./A. depending on soil type and apply late-March-mid-May

Herbaceous Weed Control• Common grasses

– Bermuda grass– Bahiagrass– Johnson grass– Fescue– Broomsedge

• Woody species– Persimmon– Blackgum– Sweetgum– Ash– Hickory– Sumac

• Broadleaf weeds– Fireweed– Goldenrod– Curly dock– Horsetail– Ragweed– Smartweed– Pigweed

• Vines– Trumpet creeper– Poison Ivy– Virginia creeper

Herbaceous Weed Control (HWC)

• Two options -- add to site prep -- post plant application

HWC-Loblolly

• Site prep addition -- 3 oz./A. Oust XP or Spyder OR -- 4 oz./A. Oust Extra (Oust + Escort)• No surfactant

HWC-Loblolly

• Post plant application -- 4 oz/A. Arsenal AC +2 oz/A oust XP – OR -- 4 oz/A. Arsenal AC + 4 oz/A. Oust Extra

• No surfactant

HWC- Shortleaf

• Site prep addition -- 3 oz/A. Oust XP

• No surfactant

HWC- Shortleaf

• Post plant applications -- 4 oz Arsenal AC/A. + 2 oz Oust XP/A. -- OR -- 10-13 oz/A. Oustar

• No surfactant

HWC – Bermudagrass pasture

• Select (clethodim) – 16 oz/A. + NIS – use with single or split application ( fair- good control with single application)

• Fusilade DX ( fluazifop-P-butyl)- 16-24 oz/A. In first application and 12-24oz/A. in second application (add NIS to both) – split applications are required for best results

Woody Release

• Occasional use following burn only, mechanical site prep or no site prep

• Usually in second growing season, but could be in any of first 4 growing seasons

• Choice of materials and rates is now restricted

Woody Release - Loblolly

• 12-16 oz./A. of 4-lb. imazapyr• 12-16 oz/A. of 4-lb imazapyr + 1 oz/A.

Escort XP ( blackberries, winged elm, ash)

Woody Release – Shortleaf

• If hardwoods are a problem on a site, use chemical site prep

Mid-rotation Brush Control (MRBC)

• Applied following first thin to control encroaching hardwoods

• Requires 4-7 years to see full impact• Cost-effective if hardwoods are >5% of

total basal area• Aerial application or ground application

MRBC-Loblolly• 12-16 oz/A. of 4-lb. imazapyr (aerial)—OR– • 12-16 oz/A. of 4-lb. imazapyr + 1 oz/A. Escort

(aerial) – OR –• 24-28 oz/A. Chopper GEN2 (ground) –OR—• 32-40 oz./A. Chopper (ground)– OR—• 4 qts./A. of 4-lb. glyphosate (ground)• Keep spray off foliage of pines when using

ground application• Add NIS

MRBC- Shortleaf

• Lack of research results• 4 qts. of 4-lb glyphosate + NIS ( ground)

Summary• Many products available for all the different

applications• Loss of patent on imazapyr and glyphosate has

drastically changed the economics of herbicide aplication in forestry

• Spectrum of control and cost/acre are and will continue to be primary factors in these decisions

• Sensitivity of shortleaf to imazapyr presents some challenge, but control is still obtainable

Hardwoods

• Oaks – red and white oak groups• Sweetgum• Blackgum• Persimmon• Walnut• Ash?

Herbicide Use

• Site prep• Herbaceous weed control • Timber Stand Improvement “TSI”• Preparation for natural regeneration

harvest

Scenarios for tree planting

Row crop Old fields Cutover sites Natural regeneration

Vegetation Control Options• Mechanical

– Chainsaw– “Mowing”– Bulldozer

• Chemical– Broadcast spray with herbicides– Basal bark applications– Injection

Pines vs. Hardwoods• Comparative caution must be taken when

using herbicides in hardwood settings– Both immediate and residual effects

• Labeled post-plant products for hardwoods– Far and few………

vs =

Old Fields and Row Crop

• Thousands of acres of abandoned agricultural fields are being re-established in hardwood forests annually

• Many of these plantings have been considered unsuccessful

Artificial Hardwood Regeneration

• In bottomland sites competition a major factor

• Lack of implementation of weed control a major factor

New Ideas Impacting Competition Control

• Mixed species stand development• Lack of “usable” site prep herbicides

– Soil active “pine” herbicides• Need for site preparation in hardwood

plantings?• More options for post-planting control

Chemical Options• Single Product• Tank Mixtures• Products used include glyphosate,

imazapyr, triclopyr, dicamba and others• Chemical site prep will not provide

residual herbaceous weed control during the first growing season

Site Preparation – Mowing and Spraying

Competition Sources• Common grasses

– Bermuda grass– Bahiagrass– Johnson grass– Fescue– Broomsedge

• Woody species– Persimmon– Blackgum– Sweetgum– Ash– Hickory– Sumac

• Broadleaf weeds– Fireweed– Goldenrod– Curly dock– Horsetail– Ragweed– Smartweed– Pigweed

• Vines– Trumpet creeper– Poison Ivy– Virginia creeper

Competition Control

• Herbaceous weed control– Pre and post emergent options

• Improper application = high risk of damage• Must use the proper chemical at the

proper time

Application Timing• Pre-emergent = high success

– Avoid damage potential of crop trees• Post emergent is feasible

– Oxyfluorfen• Red oaks

– Clopyralid– Grass herbicides

• Combination of treatments– May need to reduce application rate

May

July

Year After Treatment

Herbicides for Herbaceous Weed Control

• Sulfometuron methyl – Oust XP • Oxyfluorfen – Goal 2XL • Clopyralid – Transline • Glyphosate – Accord XRT II

– Directed spray • Grass Herbicides

– Clethodim – Envoy or SelectMax – Fluazifop-butyl – Fusilade DX – Others

Herbaceous Weed Control• Standard: Oust XP

• 2oz/ac @ 10-15 gpa preemergent• Up to 4oz/ac• Adjust for pH

• High pH (may have adverse affect)• Low pH (may get by with less)

• 5-6ft bands or broadcast

• Other options:• Pre-emergent

• Goal 2XL (64 oz/sprayed ac)• Post-emergent

• Select (8 – 16 oz/sprayed ac)• Fusilade DX (16 – 24 oz/sprayed ac)• Goal 2XL (32 oz/sprayed ac)• Transline (21 oz/sprayed acre)

Always pay attention to label!!!Crop species

Conifer and hardwoodResistant speciesApplication timingSusceptible speciesApplication ratesRestrictive use informationOther information

HWC• We expect:

• Up to 75% greater survival and increased growth using HWC

• More typically – 25 – 30%• Competition for water

• Wet years = less benefit• Dry years = more benefit

• Other considerations:• pH• Resistant species • Onsite water

• Oust XP vs Goal 2XL

HWC Findings

• Many research applications have used HWC (Oust XP)• cherrybark oak, Nuttall oak, Shumard oak, water oak,

willow oak, white oak, post oak, burr oak, overcup oak, swamp chestnut oak, live oak, green ash, common persimmon, red maple, bald cypress, winged elm, sugarberry, sweetgum, and American sycamore (19 spp)

• No phytotoxic effects observed if label rates and application instructions are followed.

• No injury noted from Goal 2XL or grass herbicides in several studies.• Avoid crop oil as an adjuvant

Clearcuts

• Planting in cutover sites can be successful• Harvest needs to be “complete”• Mechanical site prep helpful• Herbaceous and vines are the major

concern– Can spray a pre-emergent herbicide to help

control

Single Stem Injection - TSI

Remove all non-oaks between 1” DBH and 6” DBH

Common Chemicals

• Triclopyr – (Garlon 3a)– 50% concentrate and 50%

water– Apply in a continuous frill

around stem, 1 ml per 3 inches DBH

• Glyphosate – (RoundUp)– 5.4 lbs./gal, 40% percent

concentrate and 60% water– Apply in a continuous frill

around stem– Growing season best

• Imazapyr – Arsenal AC

– Up to 25% concentrate and 75% water

– Apply 1ml solution per 3 inches DBH

– Year round except during green up, fall best

Why Imazapyr?

• Only option for wide spacing injection

• Highly effective on wide spectrum of species

What is “wide spacing injection”?

• 1 hack per 3” diameter at breast height– < 3” dbh = 1 hack– 3-6” dbh = 2 hacks

• 1 ml of 20% Arsenal AC aqueous solution per hack

Herbicide Information Sources

• www.uaex.eduPublications

• Forestry Sections• Pages 179 – 184• HWC• Site prep• Injection• Woody release• Susceptibility

ratings

Herbicide Information Sources• www.clemson.edu

Extension Natural resources

Forestry

• Sections• Herbicide descriptions• HWC• Site prep• Injection• Woody release• Susceptibility ratings

Herbicide Information Sources• Public • Private

– Consulting foresters– Private applicators– Herbicide distribution

companies

Thank You!