If you've hesitated to adopt no-till because of weed-control concerns, worry no more. "We have the herbicide tools to do the job on both annual and perennial weeds in no-till soybeans and corn," says University of Wisconsin weed scientist Chris Boerboom.
Herbicide expense might be slightly higher for no-till because of the burndown that is needed, says Boerboom. However, the costs of full-width tillage - seedbed preparation, fuel and labor - offset that.
The keys to successful weed control in no-till are knowing the weeds you have, planning a course of action based on those weeds, and then making timely herbicide applications.
To be successful, you need to have weeds under control before you plant. No-till weed control programs for soybeans and corn usually start with a preplant burndown of Roundup or Roundup plus 2,4-D.
But Ohio State weed scientist Jeff Stachler recommends the following approach: "For soybeans, whether conventional or Roundup Ready (RR) varieties, we see success with a two-stage program. If perennials aren't a problem, apply a 2/3 to full rate of Sencor or 3-5 oz Canopy, plus 2,4-D, as a burndown, before grasses get established."
If a no-till field has perennial weeds, Stachler recommends using Roundup or other glyphosate product as a burndown and in a post application on RR varieties.
"In the postemergence phase of treating conventional no-till soybeans, select the herbicides that control the weeds you have," Stachler says. "Apply them before weeds exceed 6"."
For no-till corn, Stachler also recommends a two-stage program. "Go with 2-4,D, plus any atrazine premix at 1/2 to full rate, as the burndown," he says. "The full rate can provide season-long control, especially following RR soybeans. The lower rate provides about four weeks of control." Before grasses are 4" tall, come back with the appropriate herbicides for your weed spectrum.
Knowing the weeds and their density in each of his fields is veteran no-tiller Alan Madison's first task. The Princeton, IL, producer then selects products and rates accordingly.
He plants both RR and STS soybeans. He uses a Roundup/2,4-D burndown on the RR and Authority/2,4-D on the STS. Madison returns with Roundup on the RR and Synchrony/Poast Plus on the STS.
For corn, he burns down with Roundup/2,4-D, plus a 1/2 to full rate of Dual on some fields. "We have three basic programs for corn, based on the weed history of the field," says Madison. On fields with broadleaf pressure and some grass, he applies Balance, Dual, 2,4-D and atrazine pre-emergence.
"For fields with moderate grass and broadleaf pressure, we apply Basis Gold and Clarity at the five-leaf stage. With heavy grass and broadleaf pressure, we grow Roundup Ready or Liberty Link hybrids and apply Roundup or Liberty."