Get More Post-Emergence Pop

Get More Post-Emergence Pop

With the issues regarding resistant weed problems over the past few years – plus decent early season field conditions in most areas – growers took their preemergence residual weed control efforts to heart before putting their planters in the field.

According to Jason Norsworthy, professor of weed science at the University of Arkansas, good temperatures and timely rains helped activate early residuals in the Mid-South and gave most growers clean fields for planting. But, he points out, there’s still plenty of work to do. Warmer temperatures are great for young cotton plants. Weeds, too.


“Liberty and glyphosate are extremely different,” said Norsworthy. “Glyphosate is a systemic herbicide and works quite well at very low spray volumes. Liberty is a contact herbicide. The more coverage you get, the better the efficacy is going to be.”

Coarse droplets may work fine for glyphosate applications, but Norsworthy suggests a medium droplet size for Liberty applications. “With Liberty, you have to cover the entire plant in order to kill it. We’d like to see 15 gallons of water with Liberty to help achieve optimum weed control.”

Growers can use different tip patterns and other strategies to get the droplet size they want, including attacking weeds from multiple angles in one pass.

“TurboDrop DualFan nozzles are 10 degrees forward, 50 degrees back,” explained Will Smart of Greenleaf Technologies in Covington, LA. “By alternating them forward and backward on the boom, we can create four distinct spray patterns going down to the target.

“Because the droplet size and angle are slightly different from the front to the back of the nozzle, it puts smaller droplets in the middle and bigger droplets on the outside. That helps with drift control and also helps pull smaller droplets down into the canopy or onto the weed.”

“Ground speed is important,” pointed out Norsworthy. “But as ground speed increases, we start putting out less water and spray volume, and that’s going to be a problem.”

That makes boom height even more important.

As a standard, nozzles are rated for a certain boom height, based on nozzle spacing. Proper height for maximum coverage with most nozzles is approximately 20 to 24 inches.

“Contrary to what some people believe, raising the boom does not increase coverage,” added Norsworthy. “You actually get greater off-target movement and uneven distribution of the product.

“It’s vitally important that, for the nozzle used on that boom, growers have the correct spray height in order to get optimum efficacy.”

Liberty Controls Weeds

Crops with the LibertyLink trait allow growers to spray Liberty herbicide in-crop for non-selective post-emergence weed control, including control of Palmer amaranth, giant ragweed, waterhemp and marestail.

Combine Liberty herbicide with the LibertyLink trait found in select FiberMax and Stoneville varieties for the preeminent weed management system.

FiberMax and Stoneville also offer varieties with GlyTol LibertyLink, a stacked herbicide trait that allows full-labeled-rate applications of both Liberty herbicide and glyphosate without damage to cotton plants.

Key Take-Aways – Liberty herbicide:

  • Fast acting. Controls weeds within days versus weeks.
  • Part of an Integrated Weed Management System that includes the use of residual herbicides and/or tank mixes as appropriate.
  • Apply early when weeds are no more than 3 to 4 inches tall.
  • Warm temperatures, high humidity and bright sunlight improve herbicide performance.

For more information, visit the BayerCropScience website.