Weed Control

Weeds Competition Space Light Nutrient Water Physical Damage Morningglories Honeyvine Milkweed

Tolerance to Competition Weed free for 6 weeks Tobacco canopy tolerates late competition Weedy for 4 weeks Weed Control after weedy problem No competition

Cultivation Shallow (1 inch deep) Reduces root damage Doesn’t disturb herbicide placement Shears of weeds Breaking crust

Cultivation Deep Cultivation Damages roots Brings up untreated soil Misconception? Brings up moisture during a drought

Rolling Cultivators Shallow Cultivation Scrapes surface Hills plants Faster Speed

Ideal Herbicide Controls Weeds Broadleaf Grasses No Crop Injury Non-persistent to cover crop or rotational crop No drift or run-off Safe for applicator

Prowl 3.3EC Weed Spectrum Good Control Annual grasses Many Broadleaf weeds Pigweed Poor Control Rhizome Johnson Grass Hairy Galinsoga Common Ragweed Cocklebur Suppression Morningglories

Application Rates 2 to 3.6 pts/A Incorporation 1 to 2 inches Photosensitivity Possible sun breakdown Suppresses germinating weed seeds Most in upper 2 inches Crop safety Plant roots below treated areas

Activity & Mode of Action Root & shoot inhibitor Symptoms Root pruning Stunting Mitotic poison Not taken up by plants

Symptoms

Symptoms – Phosphorus Deficiency

Persistence Can cause cover crop damage especially in dry seasons

Command 3 ME Weed Spectrum Good Control Annual Grasses Most Broadleaf Weeds including Common Ragweed Hairy Galinsoga Velvetleaf

Command 3 ME Poor Control Pigweeds Seedling & rhizome Johnsongrass

Application Rates 2 to 2.67 pts/A Placement Surface application Cover crop safety Drift Post-transplant Within 7 days after transplanting

Activity & Mode of Action Photosynthesis inhibitor Damages Chlorophyll Turns plant white

Persistence Cover crop damage

Spartan DF Weed Spectrum Good Control Most Broadleaf Weeds Including Morningglories Yellow Nutsedge

Spartan DF Fair Control Annual grasses Poor Control Common Ragweed Seedling & rhizome Johnsongrass

Application Rates (8 fl oz/A) (10.1 fl oz/A) If Morningglories or nutsedge are major weed problems Placement Best not incorporated Due to crop safety OK to scratch out tractor track

Activity & Mode of Action Photosensitizes Plants actively take-up Exposure to sunlight causes membrane disruption Susceptible plants turn necrotic and die

Persistence Season long control Grass cover crops are less sensitive

Devrinol 50DF Weed Spectrum Good Control Annual grasses Fair to Poor Control Most Broadleaf Weeds Crop Safety Good

Application Rate (2 lb/A) Usually in combination with Tillam for improved broadleaf control Post-transplant OK but pre-emergence to weeds

Activity & Mode of activity Root growth inhibitor Persistence 12 month - can cause cover crop injury especially when applied post-transplant

Tillam 6E Weed Spectrum Good Control Annual grasses Nutsedge Fair to Poor Control Many Broadleaf Weeds Crop Safety Good Damage possible under specific conditions

Application Rate (2.67 qt/A) Usually in combination with Devrinol for improved broadleaf control

Activity & Mode of Activity Taken up by plants and translocated to shoots Has effect on meristemactic tissue

Persistence 3 to 6 weeks Highly volatile Readily leached by in soil Can reverse leach after rainfall

Weed Control in Burley Tobacco Fayette Co. – David Tucker Farm

Poast 1.53E Weed Spectrum Good Control Annual & perennial grasses No Control Broadleaf Weeds Application Rate 1.5 pts/A +Crop oil concentrate (1 qt/A) Post-emergence

Activity & mode of activity Taken up by plants and translocated throughout Slow acting Persistence None

Diagnosing Chemical Damage in Tobacco Look for symptom Stunting Leaf distortion Abnormal vein patterns Discoloration Look for possible sources of chemical exposure Drift Other crops near by Right of ways Contaminated Sprayer Contaminated Water Supply Contaminated Fertilizer or Spreader Equipment

Triazines Chemicals Atrazine Simazine Symptoms Dead tissue between secondary veins Green or yellow tissue adjacent to vein

Triazine Test < 0.05 ppm No damage Injury possible depending on climatic conditions > 0.20 Injury expected Run-off Contaminated Sprayer Corn Sprayer Back Siphon Contaminated Fertilizer Buggy Use of same buggies used for corn Crop Exposure

Growth Regulators 2,4-D, etc. Damage only to developing leaves at time of drift Can assess date of exposure Banvel Similar to 2,4-D But damage more persistent Tordon Extreme sensitivity in tobacco.3 ppb Water Soluble Persistent in soil

Growth Regulator Symptoms

Accent/Beacon Form Johnsongrass control in corn Drifts for a considerable distance Yellowing Leaf tip Spots Causes restricted Vein (stem) growth Lamina puckers

Accent/Beacon - Symptoms

Callisto

Unknown

Sheep Dip

Skunk Damage