Weeds can compete with vegetables, reducing yield or affecting crop quality, and can serve as alternate hosts for diseases. Weed management is easiest to accomplish and most critical when the crop is young and actively growing.
Weeds emerge from seeds present in the soil. Preventing deposits of seeds is key to managing weeds long-term. Sanitize areas adjacent to the garden and ensure that materials, such as manure, composts, mulch and equipment, are free of weed seeds. Keeping the soil covered using a cover crop or mulch material also can help.
The stale seedbed strategy, cultivating the seedbed ahead of time, followed by a secondary cultivation or flaming to kill germinated weeds prior to planting partially depletes weed seeds already present in the soil.
Applying mulch is effective. If using straw or lawn clippings as mulch material, make sure it was not previously treated with herbicides or fertilizer-based herbicides.
Emerged annual weeds may be easily removed during the early stages of growth. Hand-weeding or simple machinery, such as a sharp hoe or cultivator, flamer or finger-weeder, can be effective for weed management. Growing points of annual grasses are at or slightly below the soil surface and must be removed for successful control.
Tilling soils where perennial weeds, such as Canada thistle or Johnsongrass, are present can aggravate the problem by chopping vegetative propagules and spreading them.
Natural products, such as vinegar (with a concentration of at least 12.5% acetic acid), effectively controls young broadleaf weeds; however, it does not control grasses, perennials or larger broadleaf weeds. A shielded sprayer is recommended if spraying vinegar within rows to avoid crop injury.
By Rakesh Chandran, WVU Extension Specialist – Weed Science