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 3.3ECWeed 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

Symptoms – Phosphorus Deficiency

PersistenceCan 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 TobaccoFayette Co. – David Tucker Farm

0

20

40

60

80

100

% C

on

tro

l

Annual Grass 75 86.25 88.75 95 97.25 0 15.4

Pigweed 85 15 95 97.25 88.75 0 23.8

Yellow Nutsedge 82.5 87.5 97.5 95 98.75 0 8.6

Common Ragweed 96.25 100 87.5 91.25 100 0 10

Morningglories 87.5 57.5 92.5 95 98.75 25 37.2

Carpetweed 0 5 37.5 0 22.5 0 34.8

Prowl CommandSpartan

4F

Prowl + Spartan

4F

Command + Spartan

4F

Weedy Check

LSD

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

0.05 - 0.20 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