Some Texas grain producers expect Roundup-resistant volunteer cotton to pop up in corn and sorghum fields this coming season due to a dry fall and winter, according to a Texas AgriLife Extension Service expert.

"We are facing a similar situation to the 2009 season, when volunteer cotton was a problem in corn," said Dr. Gaylon Morgan, AgriLife Extension cotton specialist. "Volunteer cotton in non-cotton fields is especially important to producers in South and Central Texas who are actively involved in the Boll Weevil Eradication program."

Though a problem, Morgan said it's important for producers not to get discouraged and treat volunteer cotton during the early stages. If left until later, treatment options begin to be limited.

"We've found only four products that were effective at the five-to six-leaf stage," he said.

Attendees at the recent Texas Plant Protection Association Conference heard the latest research efforts led by the AgriLife Extension team of Danny Fromme, Morgan, Matt Matocha, Paul Baumann and Dale Mott.

Research trials

Research trials were funded by the Texas Corn Producers Board and the Texas Cotton Producers. The problem began during the drought of 2009 and has continued to escalate, Morgan said.

"The key is to manage the volunteer cotton while it is small and while more herbicides are effective," he said. "If the volunteer cotton is not destroyed early in the season, the cotton plants persist under the corn canopy, then following harvest the cotton plants will flourish and will be an excellent host for the boll weevil."

AgriLife Extension trials were conducted at four locations across the state from the Panhandle region, South Central Texas and South Texas.

Status (5 ounces), Laudis (3 ounces), and Halex GT + Atrazine (58 + 32 ounces) were the only over-the-top products that provided 99 percent control at the one/ two-leaf stage with greater than 1 percent volunteer plants at 65 days after treatment.

"Other products, such as Ignite 280 and Sharpen, were highly effective but must be applied through hoods or post-directed," Morgan said.

At the five-leaf stage, Starane Ultra (6.4 ounces), Status (5 ounces-10 ounces) and 2,4-D Amine (16 ounces) over-the-top provided greater than 90 percent control of volunteer cotton, Morgan said, but none completely prevented volunteer plants, which ranged from 4 percent to 11 percent at 70 days after treatment.

Control costs

Producer costs per acre were minimized when applications were applied during early plant growth. At the one/two-leaf stage, the cost per acre for Status was $13.25, Ignite 280 ($11.33 per acre), Laudis ($13.59 per acre). Some less expensive products were evaluated, like 2,4-D and atrazine, but they were slightly less effective in this trial.

"Looking ahead to next growing season, the problem is waiting to happen as many of the cotton seeds left over from pickers/stripper are in the ground, but it's been too dry for germination," Morgan said.

"Based on the current weather patterns, producers will need to make plans to deal with volunteer cotton this spring. Additionally, producers will need to pay attention in post-harvest of corn because any surviving cotton plants tend to flourish once corn begins to mature," Morgan said.

"After corn harvest, producers need to be take care of any volunteer cotton plants in a timely manner with chemical or mechanical methods," he said. "Volunteer cotton is a concern both from the frontend and after-harvest of the grain crops. In a producer's defense, they are juggling application timings and the economics of management options. Volunteer cotton is a challenge to manage. However, this is an important issue since it ties directly into the boll weevil eradication efforts and is enforced by the Texas Department of Agriculture."

b-fannin@tamu.edu