PMN Crop News Homepage   



Posted 23 July 2012. PMN Crop News.


Experts Caution Cotton Growers to Look Out for Target Spot

Early detection and fungicide use keys to preventing potentially devastating losses


Source: BASF Crop Protection Press Release. www.basf.com


Research Triangle Park, North Carolina (July 12, 2012)--Cotton growers in southwest Georgia and southern Alabama are at high risk this season for Corynespora leaf spot, a troublesome crop disease also known as target spot. This disease can be devastating to cotton if not treated early in the season.

 

‘New’ disease could wipe out profits

Over the past five years, cotton growers have seen increasing yield losses from target spot, which is relatively new to this area.

“Target spot is a damaging cotton disease affecting growers across the region,” said Sandy Newell, BASF Technical Service Representative. “If target spot is not properly treated, cotton growers could experience yield losses ranging from 15 to 50 percent.”

Target spot begins as lesions on leaves eventually leading to defoliation. Ultimately, yields are reduced by this leaf loss. The most severe cases of target spot are seen when growers plant cotton in back-to-back seasons.

“The spores of the fungus will survive between seasons in the crop debris,” said Bob Kemerait, Ph.D., Extension Plant Pathologist, University of Georgia. “As rain and irrigation splash the spores from the ground to the developing leaves, the spores will spread too as the crop continues to develop and grow.”


Early detection key to protecting cotton

Kemerait recommends cotton growers include diseases on their list of pests when scouting throughout the season.

“Early detection is the key to managing this disease,” Kemerait said. “With every rain the chances are increased for target spot, so growers should monitor fields closely.”

Early in the season, target spot is hard to differentiate from other diseases. If growers find unusual spots, they should take samples to a local university extension agent for testing.

“Growers need to begin scouting early, so they can find and treat target spot before it creates a problem,” Newell said.

It is critical to look well into the canopy and away from edge effects when scouting, as target spot defoliation often begins in the lower canopy and can be hard to see from the edge of a field.

Weather conditions are a good indication of the likelihood of target spot. Target spot thrives in areas of high moisture and humidity, and is prevalent when rainfall is abundant. Growers who observe these weather conditions should be particularly cautious of the disease.


Well-timed fungicide applications for effective disease management

Growers facing target spot can manage the disease with well-timed applications of TwinLine® fungicide. TwinLine fungicide provides excellent broad-spectrum disease control and Plant Health benefits on cotton. It demonstrates superior foliar disease protection as well as post-infection control.

“It is important for growers to make the first applications of TwinLine fungicide at first bloom and an additional application two to three weeks later,” Newell said. “Initial applications should be made prior to canopy closure in cotton.”