Weed Management in HORT crops

week 12

why are weeds bad?

• compete with crops for light, water, and nutrients

  • reduce yields and quality

• reduce harvesting efficiency

• host pathogens

• allergens

• unatractive

DIVERSITY: plant parts consumed

seeds: sweet corn/dried beans

fruit: tomatoes, peppers, cucurbits

pods/capsules: peas, beans, okra

Influrescences: broccoli, cauliflower, zucchini

roots: radish, carrot, sweetpotato

tubers: potato

Bulbs: onion, garlic

leaves: lettuce, spinach, collards, turnips, kale, mint

stems: asparagus, kohlrabi

petioles: rhubarb

cultivation

occurs while weeds are small and before the crop canopy closes

uproots weeds

may not reach weeds along planted row

cultural control

in row and between row plant spacing

planting date

cultivar selection

crop rotation

vigorous crop growth

herbicide considerations:

between or within row?

bearing or non-bearing?

broadcast or directed?

hand weeding

used by commercial producers

targets escaped weeds

labor intensive

expensive

home gardens control

heribicides not recommended:

• too many crops

• not suitable equipment

• inexperienced people

hand hoeing is best

mulcing:

• conserves moisture, reduces light infiltration, controls temperature

• insulates soil (can cause soil to be too warm or too cool)

  • organic (straw compost wood) OR synthetic (polyethylene)

how many crops and acres are produced in illinois?

30 primary crops and about 300,000 acres

types of commercial vegetable production

processing (contract)

fresh market (local food stand/contract)

indiana crops:

tomatoes

melons

mint

illinois crops:

sweet corn

tomatoes

beans

horseradish

onions

carrots

cabbage

peppers

peas

vine crops

pumkins

IMPORTANT cultural and mechanical weed control practices:

cultivar selection

seedbed prep

tillage after planting

crop rotation (land suitability and irrigation limits)

herbicides

multiple cropping systems so soil persistence is a concern

herbicide clearance is a problem on small acreage crops

• vegetable and fruit crops = 1 billion

• indiana corn = 4.4 billlion

• indiana soybean = 3.4 billion

  • companies are not interested because they cost the same to clear a vegetable chemical as it does for a corn one. (even if herbicide is safe they dont spend money to get them cleared???)

Herbicide clearance:

USDA IR-4 committee - works with states on minor crops to get labesl approved by epa

additional problem since many crops are eaten immaturely so residual is a concern

differences in varietal tolerance in specialties and vegetables

major herbicides:

prefar

basagran

post graminicides

trifluralin

clomazone - pumpkins

Perennial weeds in perennial vegetables

crops: asparagus and tree fruits

weeds: field bindweed, common milkweed, honeyvine milkweed, canada thistle

DRIFT of what, and problem for what?

of 2,4-D and dicamba

problem in cucurbits, peppers, tomatoes

CARRYOVER CONCERNS

triazines, sulfonylureas, imadazolinones

Purslane

problem in slow growing crops

favored in fertile soils

vegetable crops grown in fertile soils

herbicide program dictated by?

commercial vegetables grown under processor contract so the company usually dictates the program

in 1998 ornamentals profited illinois how much

1.2 billion

container stock (sm. plants)

• sterilized soil- methyl bromide (discontinued), steam sterilization

• field stock (shrubs/trees) - post graminicides, simazine, trifluralin most popular

• problem is even greater since there is a large number of species in a small acreage per nursery