Post-Harvest Field Prep Can Reduce Weed Problems at Planting
October 27, 2015 This year’s harvest is nearly complete. And as growers look across their bare fields, they should be thinking about what’s needed to get ready for next year’s plantings.
Larry Steckel says it’s never too early to get a jump on knocking soil seed banks down for next season.
“Now can be a critical time, especially in fields where cotton, corn and soybeans have been out for a while,” says Steckel, University of Tennessee Extension weed specialist. “Harvest may have chewed the fields up, but we can still see some pigweed come back up and produce seed prior to a first frost. Anything growers can do to keep the soil seed bank down is a big plus for next year.”
Growers do have multiple options for fall management of problem weeds.
Tillage is an excellent option, especially on flat ground.
Mowing stubble to a low level can also help. “Weeds may come back a bit and produce some seed, but mowing does knock some of the seed bank down,” states Steckel.
Herbicide applications in a fall burndown should also be considered. Steckel suggests Gramoxone with a residual herbicide for fields that will not be planted to wheat.
“We have some folks that do all three,” points out Steckel. “We know we’re losing herbicide effectiveness. So the lower the weed seed numbers, the less likely we are to find more biotypes resistant to the herbicides that are left.”
Steckel and his graduate students have also been gauging the value of fall cover crops for weed suppression. He suggests that growers consider adding a cover to their plans.
“A blend of wheat and cereal rye with crimson clover or vetch has worked best for us,” he says. “That has given us the most residue.”
Steckel says they make spring planting into the residue easier through what he calls strip burndown. Using a sprayer set up on an RTK, they kill off 10-inch bands in the field in February. The entire field is then sprayed and burned down a few weeks before planting.
“We drop the planter in on those burned down strips,” he noted. “We’ve done this for two years now, and it has made a big difference in getting a good cotton stand.”
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