Growers commonly do this for berry crops; why not more for the vegetables? One example I know of that works very well is to put down clean straw or hay in the aisles between black plastic. It also helps with disease control. Mulch also works well with summer squash and some Brassica crops. Galinsoga and many other annual weeds will be well controlled by a good mulch. Perennial weeds will not and will thrive under mulch. For them, try cover crops and fallow treatments.
Preferably, this includes a legume/grass sod crop but at least with crops that are tilled in different seasons. Weeds will build up more if they are consistently favored by tillage at their favorite time. Warm season weeds such as pigweed, purslane and crabgrass are favored by tillage in June and July -- and will be smothered out by mulch or cover crops at the time. Galinsoga seeds have only a short life in the soil. A field rotated into three years of hay would have a dramatic reduction in galinsoga pressure plus an improvement in soil tilth.
Many Midwestern studies have shown yield increases of 10% or more in corn and soybeans in their first year of rotation, compared to continuous cropping. This is called the rotation effect. No doubt it works for most vegetables as well -- take advantage of it.
Use crops in rotation to get rid of pesky weeds via wider herbicide options. This should be a cornerstone of weed IPM. For instance, growing sweet corn allows one to use Dual, which can help clean up a field with heavy annual grasses, galinsoga, nightshade and nutsedge. If you cultivate the corn as well, so much the better for your weed control. If horse nettles are a problem in a field, plant an early maturing crop such as peas, snap beans, cucumbers, summer squash, etc. Then, either till repeatedly after the crop is harvested (i.e., fallowing the field), or spray with Roundup and Banvel or 2,4-D. Velvetleaf is quite susceptible to cultivation, so rotating into a crop that you can cultivate thoroughly can help. Field crops may present more herbicide options. As much as possible, plan so that herbicide carryover does not preclude your rotation choices.
Use them in rotation, as above. Fill in windows before or after a crop, of five weeks or more during the growing season, with a cover crop that will grow rankly in that season. Plant it thickly. For instance:
|Warm season||Sundangrass, Japanese millet, cow peas, soybeans, buckwheat|
|Cool season||Oats, rape, field peas|
|For overwintering||Rye, hairy vetch, red clover|
If the window is less than five weeks, consider fallowing during that period by harrowing the field every 10 days. Don't let weeds escape and set seed! As cover crops grow, they smother weeds that germinate. When you till the cover crop under, the weeds are also destroyed before they go to seed. Even if the cover crop has not reached its full growth, till the stand under if you see weeds beginning to flower.
Learn about the best tools for your crops and soils and how to use them. Talk to other growers who cultivate. Two excellent resources are the video, Vegetable Farmers and Their Weed Control Machines, and the book, Steel in the Field.
This is a technique used to clean up a field before planting the crop. Prepare your seedbed, but delay planting until a flush of weeds emerges. Then shallowly harrow them, flame them or spray with a slow rate of Roundup before seeding the crop. You will be depleting the weed seed pool in the top inch of soil. This process may be repeated several times if your planting schedule permits. Stale seedbed does not work well against perennial weeds, unless herbicides or repeated flaming are used.
This involves repeated discing or harrowing of the field during
a substantial mid-summer time period (often six to eight weeks)
to till weeds. It can be done after some very early crops such
as spinach or lettuce; or incorporated into a year off with cover
crops. Fallowing is an effective way of cleaning up fields infested
with most weeds. It is a last resort for most growers because
of having to take the field out of production, and because it
is relatively hard on the soil.
Reprinted from Grower, New England Vegetable and Small Fruit Newsletter, Volume 98-7, July 1998
This information was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate.
The information in this material is for educational purposes. The recommendations contained are based on the best available knowledge at the time of printing. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The Cooperative Extension system does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available.All agrochemicals/pesticides listed are registered for suggested uses in accordance with federal and Connecticut state laws and regulations as of the date of printing. If the information does not agree with current labeling, follow the label instructions. The label is the law.Warning! Agrochemicals/pesticides are dangerous. Read and follow all instructions and safety precautions on labels. Carefully handle and store agrochemicals/pesticides in originally labeled containers immediately in a safe manner and place. Contact the Connecticut Department of Environmental Protection for current regulations.The user of this information assumes all risks for personal injury or property damage.Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Kirklyn M. Kerr, Director, Cooperative Extension System, The University of Connecticut, Storrs. The Connecticut Cooperative Extension System offers its programs to persons regardless of race, color, national origin, sex, age or disability and is an equal opportunity employer.