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prevents weed seed production

The next table shows the net loss of grain and associated weed seeds after a three-ton truck travelled 10 km at 80 km/hour.

Weed seeds and vegetative parts of plants move with farm equipment and soil. Long distance transport is responsible for the introduction of new weeds to previously clean areas. Industrial equipment, seed and used farm machinery are the worst offenders. Equipment should be cleaned before moving from one area to another. Place a tarp over grain and soil when it is transported. In addition to preventing weed spread, tarps reduce unnecessary loss of a valuable product.

Fence lines and headlands serve as habitat for beneficial insects and wildlife. Disturbing these sites may not be necessary as long as they do not act as a refuge for weeds or insect pests. If fence lines, headlands and roadsides are sources of infestation, try planting them with native plants and grasses that are adapted to our climate and growing conditions, and thus are competitive with weeds. Mowing or grazing uncultivated wastelands helps to control weeds. If possible, delay mowing or intensive grazing until late July, to allow ground nesting birds to raise their broods.

Practice Fence Line and Headland Control

Feed hay in areas that can be regularly checked for weed growth in case the hay is contaminated with weed seeds.

Use certified seed that includes a weed seed analysis.

Preventive weed control involves all measures taken to forestall the introduction and spread of unwanted plants. Although preventive measures will reduce infestations, no program can eliminate the wide variety of weed species on a given piece of land. Success of a preventive program varies with the weed species, the amount and constancy of effort that you devote to prevention.

Weed seeds may remain viable after passing through animals, resulting in contaminated manure. Screenings used for feed should be finely ground, cooked or pelleted to ensure destruction of all the weed seeds. Poultry are most effective in destroying weed seeds as their crops grind the seeds. In order of decreasing effectiveness are sheep, horses, swine, and cattle.

Hill EC, Renner KA, VanGessel MJ, Bellinder RR, Scott BA (2016) Late-Season Weed Management to Stop Viable Weed Seed Production. Weed Sci 64:112–118

The recent rains and cooler temperatures have favored significant weed growth in field edges and fencelines. Since combines, tillage equipment, wind, and rain can all contribute to weed seed movement it is important that farmers assess late summer weed growth and do what they can to limit weed seed production. The window for reducing weed seed production via mowing is rapidly closing, but farmers are encouraged to do what they can to get a better handle on the weed seed bank, and prevent fenceline weeds from moving further into the field.

Mowing weeds now will also prevent weed seeds from getting picked up and run through the combine harvester. Combine harvesters are great at spreading weeds across the field, and by mowing weeds now we can prevent some weeds from entering the combine altogether. If fenceline weeds are not mowed now, consider harvesting around weedy fencelines this fall to prevent spreading weed seeds throughout the field.

Summary

As summer field activities wind down, harvest will soon be in full swing. Take the time now to mow fenceline weeds to prevent or minimize seed production. Fencelines are often where weed infestations start. By eliminating fenceline weeds, we prevent combine harvesters from picking up weed seeds from the field edges and pulling them into the field, where they can be further spread by harvesting and tillage equipment.

Most weeds common to corn and soybean fields are in the flowering and seed development stages of their life cycle. This means that there is still time to control some fenceline weeds before they are able to produce viable seed. Viable seeds may have already been produced by early-maturing broadleaf weeds like lambsquarters, kochia, and redroot pigweed, but later-maturing weeds like giant and common ragweed have just begun pollinating in many areas of Minnesota. Waterhemp and other pigweed species are able to produce viable seed within 10 days of pollination according to University of Illinois research, so it is important to control weeds soon after they begin flowering.

Bell MS, Tranel PJ (2010) Time Requirement from Pollination to Seed Maturity in Waterhemp. Weed Sci 58:167–173