by John Hart, Southeast Farm Press
The clear takeaway message: Farmers can’t rely on herbicides alone to control tough weeds.
Farm journalists from across the country received a short course in managing resistant weeds during the Syngenta Media Summit held Oct. 28 at the Umstead Hotel and Spa in Cary, N.C.
In a panel discussion at the summit, Dane Bowers and Gordon Vail, Syngenta’s technical product leads for herbicides; Tim Hambrick, area field crop agent for Forsyth, Stokes, and Surry Counties with the North Carolina Cooperative Extension Service; and Dorchester, Nebraska farmer Jayme Dick-Burkey all agreed that cover crops, hand pulling and tillage practices play critical roles in managing resistant weeds in addition to the use of herbicides.
The key points emphasized:
- Start clean with tillage or an effective burndown plus a pre-emergence residual herbicide application. Catch weeds when they are small.
- Always use a two-pass system. Follow a pre-emergence application with a properly timed post-emergence application. Apply at full rates with recommended adjuvants.
- Use multiple modes of action with efficacy on target weeds.
- Use diversified management programs such as cover crops, mechanical weed control and crop rotation.
- Do not allow weeds to go to seed and add to the seed bank. Remove weed escapes early.
- Utilize good agronomic practices: Narrow rows, increased plant populations and other practices that promote crop growth and competitive ability.
Syngenta’s Bowers said the use of a two-pass herbicide program is particularly important in soybeans and cotton. “It’s really critical that we do a pre-emergence and follow that up with a post-emergence application,” he said.
In addition, Bowers said utilizing the full label rate is vital. “When we use below label rates we’re not only selecting for a high level of resistance but we are also selecting over time for weeds that carry genes that might give them low levels of resistance. If we use a full label rate, we at least reduce that possibility for selecting those weeds that have low levels of resistance in the population,” he stressed.