Weeds

• A weed is defined as a plant growing out of place

• Characteristics:– Weeds grow faster than crops– Produce lots of seed with long viability– Usually have some seed dormancy– Some can also reproduce vegetatively– Some weeds have allelopathy

Cultural Weed Control

• Most garden weeds are removed manually– Long term weed control is accomplished by

not allowing weeds to set seed in the garden

• Manual = pull, hoe, till, plow, chicken tractor, weeder geese

• Don’t allow weed seed to germinate– Mulch, corn gluten, salt

Manual weed removal

Hoes

Other methods

Flame

Hot water

Vinegar

Other methods

Corn GlutenSalt

Mulch

• Most weed seed needs light to germinate

• Organic mulch – straw, leaves, Hosta Squash… can keep light from hitting the soil surface and keep weeds from germinating

• Black plastic

• newspaper

Biological weed control

• Using animals

• Crop competition

• Introducing insects or diseases

Let others do some of the weeding!

Weeder geese

Chicken tractor

Crop competition

• Large leaved crop or ornamental plants like squash or Hosta will shade out weeds.

• Peas are one of the crop plants that are allelopathic and can fight weeds chemically

Using insects and disease

• Be very careful with these!– There is a new patent on a fungus that

selectively kills crabgrass.– The DNR is releasing a small beetle that eats

purple loosestrife

Chemical control

• Herbicides can be classified as:– Contact or Translocated

• Contact=plant is injured at the point of contact• Translocated= (roundup) goes into the plant leaves

and kills roots and rhyzomes

– Residual and non-residual• Residual= has some long term soil activity• Non-residual=does not

Chemical control

• Pre-plant herbicide

• Pre-emergence herbicide

• Post-emergence herbicide

• Selective

• Non selective

Herbicides. During the fallow period, oxyfluorfen (GoalTender) can provide both preemergent and postemergent control of winter weeds. Paraquat (Gramoxone), pelargonic acid (Scythe), glyphosate (Roundup), and carfentrazone (Shark) can provide fallow bed weed control. Metam sodium is available as a soil fumigant to control soilborne diseases and nematodes, but it can also be used to control weeds, although results are not always consistent. Be sure the soil is well cultivated and moist before its application. Also available are paraquat (Gramoxone Inteon), pelargonic acid (Scythe), and glyphosate (Roundup) to control emerged weeds before planting. Glyphosate as a preplant treatment can be particularly helpful in controlling perennial weeds. The preplant herbicide benefin (Balan) is mechanically incorporated into the top 2 to 3 inches of the lettuce bed. Because benefin remains in the soil after harvest, do not plant benefin-sensitive crops such as corn, sudangrass, sugarbeets, spinach, and sorghum, following a lettuce crop where benefin was used. Depth of incorporation is important to the performance of this herbicide. If it is incorporated too deeply it will dilute the herbicide, resulting in poor performance. Mixing it too shallowly may reduce lettuce tolerance. Power driven incorporator, bed shaper units have given satisfactory results.

Chemicals for Home Gardens

• The rules for herbicide use change every year – mainly chemicals are finally tested and found to be cancer causers – or worse

• If you use these you must read the whole label.• Wear the proper protection , don’t apply on a

windy day, keep away from streams and other ponds

• Don’t put anything on your food that you don’t want to eat

Chemical control

Leaves distorted due to 2,4D injury

Common weeds

Bull thistle

Dandelion

Crabgrass

Eat your weeds

• PigweedLambs quarters

Illegal plants