WEED CONTROL IN THE HOME VEGETABLE GARDEN

HG - 06

Controlling weeds is vital to maintaining a productive vegetable garden. The two broad classes of weeds are grasses and broadleaf weeds. Within each class are perennial weeds, biennial weeds, and annual weeds.

Biennial and annual weeds can be controlled readily by conventional means. Perennial weeds usually have strong, aggressive root systems that serve as a storage mechanism from which the plants regrow. Examples of perennial weeds are Bermudagrass (wiregrass), nutsedge, and Johnsongrass. Perennial weeds frequently require herbicides for control, prior to or after the garden season.

Several good ways to control weeds in vegetable gardens are cultivating, mulching, and using chemical herbicides.

Cultivation

Cultivating the soil after weeds have sprouted in the spring will reduce weeds before planting. Frequent cultivation and hoeing between the rows and around each plant are necessary, especially during the early part of the season. Cultivation during the summer must be very shallow to prevent damage to vegetable roots. Small weeds most often are pulled by hand or covered with soil.

Cultivating with a rotary tiller or hoe and pulling weeds are labor-intensive but effective. Doing this in the morning on a sunny day will cause weeds to wilt and prevent re-rooting.

Mulching

Straw, old hay, grass clippings, black plastic, and other good mulching materials will not only help control weeds, but will conserve moisture and may add organic matter to the soil. It is best not to apply organic mulches until the soil has warmed, usually about mid-June.

Black plastic mulch can be laid in April. The soil should be moist not dried out when plastic is laid. Transplants can be put into holes cut in the plastic at desired spacings after the plastic has been in place for about one week. Apply fertilizers and work them into the ground before putting plastic down.

In particular, staked tomatoes, peppers, and most transplanted vegetables benefit from a good mulch. However, all vegetables can be mulched to control weeds. It takes 3 to 4 inches of straw for good weed control.

Chemical Weed Control

Chemical weed control in a vegetable garden can save time and work if done properly. Careless application can stunt or kill vegetables, resulting in poor or nonexistent control. Herbicides are often very specific in their safety to particular crops. A typical vegetable garden with a variety of different crops is susceptible to injury if a herbicide is applied to an area where a nonresistant crop is planted.

Don't use chemical weed control in your garden unless you are willing to measure accurately and apply materials correctly.

Herbicides are classified into three general categories:

  1. Preplant incorporated - Herbicide is applied to the soil and worked into the soil 2-4 inches deep. This is done before planting.
  2. Preemergence - Applied to the soil immediately after planting the seeds or just prior to transplanting plants.
  3. Postemergence - Applied over the top of the growing crops to kill weeds that are growing.
The following materials are recommended for home vegetable gardens since they are available in small quantities and are relatively safe to use. Many other available chemical weed-control materials are not included in this list. These herbicides will control most weeds and grasses, but a few weeds are resistant, so hand weeding is generally required.

Herbicide Choices for the Home Vegetable Garden

Treflan* Rate: 2-3 level teaspoons per gallon to cover 1000 sq ft.
Time of Application: Apply before planting snap beans, lima beans, okra, blackeyed peas, carrots, and peas. Apply before transplanting broccoli, Brussels sprouts, cabbage, cauliflower, peppers, and tomatoes. Apply and mix with top 2 to 3 inches of soil immediately (within 2 to 3 hours). A rotary tiller will do the best job; otherwise, hand-rake the top 2 to 3 inches. Plant within two weeks.

Fusilade* Rate: Will vary according to crop and age of the grass. Always read the label before applying.
Time of Application: Used for postemergence control of grasses in asparagus, carrots, onions, spinach and sweet potatoes. Will control only grasses. Will not control nutsedge. Label recommendations for application interval before harvest must be followed.

Poast* Rate: Will vary according to crop and age of the grass. Read the label before applying.
Time of application: Used for postemergence control of grasses in asparagus, cole crops, cucumbers, greens, lettuce, muskmelons, peppers, radishes, rutabagas, turnips, summer squash, tomatoes, watermelons, white potatoes, and winter squash. Will control only grasses. Will not control nutsedge. Label recommendations for application interval before harvest must be followed.

Other herbicides used on vegetable crops include Atrazine for sweet corn and Karmex* for asparagus.

These materials are often hard to find in quantities suitable for the home garden. If Atrazine (AAtrex* 80% wettable powder) is used for sweet corn, the land should not be planted with another vegetable, except corn, for 18 months, or injury may occur. Corn may be planted in the same land the same year, and all vegetables the next year. Karmex (80% wettable powder) at 3 level tbsp per 1,000 square feet may be used on established asparagus plantings in freshly worked soil before or after the cutting season, or both times. For more complete information on these materials consult your county agent.

Methods of Application

These herbicides may be applied with a sprayer or watering can. Be sure to keep them stirred or agitated.

Determine how much area in square feet you can cover with a gallon of water applied with a sprayer or a watering can. Use plain water to try this first. Then apply the herbicide. It is better to make two applications, walking in a different direction each time. Do not backtrack or double the application. Use a convenient amount of water and be sure to apply the correct amount of chemical for the area.

CAUTION: Read the label. Apply materials only on crops listed. Follow all directions and observe precautions. Avoid prolonged or repeated contact with the skin and wash thoroughly after use. Keep away from children, pets, and food.

*Trademarks of Dow Elanco, ICI Americas, BASF, DuPont Co., and Ciba-Geigy, respectively.

To the best of our knowledge, all recommendations in this are in accordance with those on product labels. However, if there is disagreement between recommendations in this bulletin and what is stated on the label, always follow the label directions.

Revised December 1990 by:

Ed Kee, Cooperative Extension
Vegetable Crops Specialist

Derby Walker, Jr., County Agricultural Agent
HG-06 2/9l