Transcript Weed Control

Weed Control
Topic 2044
Melissa M. Fowler
What is a Weed?
 Any
plant that is out of place
 Any plant that grows where it isn’t wanted
 Examples
A corn plant growing in a soybean field
 A tulip growing in the middle of a yard

Detrimental Effects
 Compete
with crops for
Moisture
 Light
 Nutrients

 Contaminate
crops and their products
Off flavored milk
 Weed seeds in a seed crop

 Carry
pathogens
Detrimental Effects Cont.
 Poisonous
to livestock
Loco Weed
 Nightshade
 Milkweed

 Increased
production costs
Cultivation
 Chemicals
 Seedbed preparation

 Nuisance
Beneficial Effects
 Prevent
erosion
 Provide food and cover for wildlife
 Reduce leaching of minerals
 Add organic matter
Eradication vs. Control
 Eradication
Killing every existing plant
 Destroying all reproductive organs

Dormant seeds
 Below ground organs

 Control
Reducing existing plants
 Presence of some weeds does not seriously interfere
with the area’s economic use.

Prevention
 Use
clean, weed-free seed
 Use clean equipment
 Grow weed-adapted crops
 Watch for weed seeds in packing material or
nursery stock
Methods of Control
 Biological
 Mechanical
 Chemical
Biological Control
 Caterpillars

Used to kill thorny shrubs
 Fungus
Velvetleaf will wilt and die
 No harm to crops or ornamentals

 Fungal
Spores
Sprayed on rice crop
 Weeds controlled within 7 to 10 days
 As effective as herbicides
 No damage to rice

Biological Control Cont.
 Allelopathy
Plants produce chemicals
 Chemicals harmful to other plants
 Chemicals exude through plant roots or will be washed
from leaves by rain

Mechanical Control
 Cultivation

Uproot and/or cut off roots
 Mulches
Layer of plant or artificial material on soil surface
 Work by cutting off light source

 Burning
(1800oF)
Flame directed on weeds for short time
 Done in cotton
 Effective for killing small weeds

Mechanical Control Cont.
 Flooding
Used on rice paddies
 Kills non-aquatic weeds

Chemical Control
 Herbicides
 Depend
on rain to wash them into soils
 Types of Application
Preplant
 Preplant incorporated
 Preemergence
 Postemergence

Herbicide Types
 Contact
Kills the part of the plant that it touches (contacts)
 Not carried throughout the plant
 Will not kill perennial weeds
 Example: Paraquat

 Systematic
Blocks metabolic activity
 Translocated throughout the plant
 Necessary to kill perennial weeds
 Example: Roundup

Herbicide Types Cont.
 Selective
Kills one type of plant but not another
 Some will kill broadleaves, but not grasses
 Others will kill some grasses and some broadleaves, but
not others
 Example: Atrazine

 All
selective herbicides are systematic BUT
not all systematic herbicides are selective.
Surfactants
 Sticking
agent added to help herbicides
stick
 Facilitate absorption of chemical
 Also known as: Crop Oil Concentrate
(COC)
Active Ingredient (a.i.)
 Ingredient
that actually kills the plant
 Pounds/ acre
 Ounces/ acre
Too little will not work sufficiently
 Too much will harm the crop and cause pollution

 Follow
label directions