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Herbicides for Sugarcane

Herbicide Basics

• What is the application timing– Common sugarcane timing

• PRE– Applied prior to weed and crop emergence– Generally soil active herbicides (some exceptions)

• POST– Applied after weeds have emerged– Can be early, mid, late– Generally over-the-top– Generally more foliar active herbicides

Herbicide Basics

• What is the application timing– Common sugarcane timing

• Post-Direct/Lay-by– Applied after sugarcane is fairly large– Direct herbicide at base of plant– Generally for herbicides that cause crop injury– Can be foliar or soil active (or both)

• Non-Crop/Fallow– Generally foliar active– Can help with hard to control weeds

PRE Herbicides

Atrazine

• Backbone of sugarcane weed control– Used both PRE and POST

• PRE– Good soil activity (2-4 qt/A)

– Controls most broadleaves

– Suppress/control many grasses

– Activity begins to fade 3-5 weeks after application

– Broadleaf activity last longer than grass activity

Evik (Ametryn)

• Generally applied POST, but some PRE

• Controls many small grasses and broadleaves– Needs to be less than 4 inches

• Less than 3 inches for alexandergrass

– Crop injury• More common with higher rates and warmer

temperatures

Evik (Ametryn)

• Rates– 0.5-1.5 lb/A (labeled)– Lower rates often used

• Efficacy?

• Tankmixture:– Often tank mixed with atrazine (2-4 lb/A) at

0.25 to .75 lb/A

Prowl H2O and Prowl 3.3 (Pendimethalin)

• Used on moderate acreage– Excellent grass control

• Can be season-long under good conditions

– Not so good on broadleaves• Tank-mix with Sencor (metribuzin) helps• Still may need follow-up for spiny amaranth

Prowl (Pendimethalin)

• Challenges– Needs rainfall/soil moisture for activity– Can be good when soil is dry

• More consistent when soil moisture is good

• Rates– Sand

• 2.4-3.6 qt/A

– Muck• 2.4-4.85 qt/A

Prowl + Sencor• Good broad spectrum PRE program

– Muck soil only!!!

– Ideally, don’t cultivate if there aren’t weeds

– Some broadleaves can come through• Spiny pigweed

– Expensive

– Can be very good with good soil moisture

• Rates– Prowl (4 qt/A)

– Sencor (1 lb/A)

K4• Registered for FL sugarcane in 2005• Mixture of hexazinone (Velpar) and diuron

(Karmex)• Applied at 2-4 lbs/A• Higher rates for muck soils, lower on sand• Good control of many grass and broadleaf

weeds• Can go out early POST• Apply to cane less than 18 inches tall

Diuron(Karmex/Direx/Etc)

• Not used much– Sand soils (binds very strongly on muck)– Better control of broadleaves than grass– Not much experience

• Crop injury?

• Rate– 1.6 lb/A PRE

Roundup Ultramax(Glyphosate)

• MUST BE APPLIED PRIOR TO CANE EMERGENCE!!!!!!!!– Excellent control of emerged weeds

• Excellent control of sugarcane if emerged!

– Timing is very, very critical– Controls some hard to manage species

• Bermudagrass• Paragrass

– Rate• 3.25-4 qt/A

Valor(Flumioxazin)

• PRE/POST-Direct – Good broadleaf control PRE

• Grass control has been variable

– Active POST on small grass and broadleaves• High levels of burn on sugarcane

– Post-direct only

• Cannot be applied over the top of sugarcane

POST Herbicides

Atrazine

• POST– Use with crop oil concentrate

• Rate still 2-4 qt/A• Controls many small broadleaves• Grass needs to be small

– 3 inches of less is ideal

• Provides residual activity

Envoke (Trifloxysulfuron)

• Applied at 0.3 to 0.6 oz/A• POST, ratoon sugarcane only• Excellent nutsedge product

– Good control of small broadleaves– Controls some small grasses– Excellent on alligatorweed, spiny amaranth

• Looks good in combination Asulox/Asulam at 0.5 gallon/A– Good, wide spectrum treatment

2,4-D Amine

• Very versatile, useful product– Controls most broadleaves

• Can use lower rates on smaller weeds• Can suppress nutsedge growth

– Probably not long-term control

• Alligatorweed activity can be good– Need good conditions for best control

2,4-D Amine

• Challenges– Can drift and volatilize

• Major problems!!!!• Follow the Florida Organo-Auxin Rule

– No volatile formulations (esters)– Application restrictions based on wind speed

» Also distance from sensitive crops– http://edis.ifas.ufl.edu/WG051

2,4-D Amine

• Rates– 0.5 to 2.0 lb ai/A

• Note rates in ai due to many formulations

– Lower end will control many small weeds– Higher rates for alligatorweed, large weeds

Asulox(Asulam)

• Excellent POST grass herbicide– Controls most common grasses

• Size of weeds is important– Can use 6 pt/A if grass is 6-8 inches or less

» Preferably less!– Use 1 gal/A (8 pt) is grass is greater than 8 inches

• Use a surfactant (0.25% v/v) or COC (1% v/v)

Asulox(Asulam)

• Challenges– Good spray coverage is very important

• Many control issues relate to coverage

– Use the proper rate• If it’s 6 inches today, it will probably be 8 inches next week

– Slow activity• Need to be patient

– Injury• We can see burning to leaves at higher rates• Can use a directed application

Asulox(Asulam)

Evik (Ametryn)

• Controls many small grasses and broadleaves– Needs to be less than 4 inches

• Less than 3 inches for alexandergrass

– Directed application• Injury will be seen on treated foliage

• Use surfactant at 0.5% v/v• Rates

– 0.5-1.5 lb/A– Lower rates often used

Sempra, Sandea (Halosulfuron)

• Excellent nutsedge control– Yellow and purple (4-12 inch ideal)– Works best under good moisture conditions– Controls some small broadleaves

• Small pigweed, ragweed (less than 4 inches)

• Use surfactant or COC– 0.25-0.5% v/v surfactant or 1% COC v/v

• Rate– 1 to 1.33 oz/A

Fallow Land Treatments

Glyphosate

• Excellent control of emerged weeds– Controls many hard to manage species

• Bermudagrass• Paragrass• Napiergrass• Nutsedge (better on yellow)• Many, many others

Take Home

• Always follow the label!!!• Several effective herbicides

– Identify weed spectrum– Apply correct rate– Apply to correct weed size

• Let the herbicide work!• We will hopefully have more options in

the future!