Target spot fungus has become a “when” instead of an “if” for Delta and Southeast soybean and cotton growers. The disease has hit growers hard the past four years, and there’s no reason to suspect 2018 will be any different.
But there is good news. University studies have shown preventative fungicide applications, such as Priaxor® fungicide, can help control the disease and prevent the devastating defoliation it can bring, while also delivering Plant Health benefits that help crops stand up to the pressures of target spot and other stress factors. The combination of Plant Health benefits from Priaxor fungicide, including disease control and growth efficiency, may lead proactive growers to much higher yield returns than if they left their fields untreated.
Target spot 101
Target spot thrives in humid, moist conditions, which means it is a threat in tropical or subtropical environments. But the disease has continued to encroach farther and farther north. Growing seasons with heavy rainfall have been some of the hardest hit by target spot. However, even a relatively dry 2017 provided no reprieve to growers.
One reason for the disease movement is well-managed soybeans and cotton are grown in environments ripe for target spot — those that are heavily irrigated. The added moisture, combined with summer heat, is a great recipe for the humidity that helps the foliar disease thrive. The exact conditions growers want for their soybeans and cotton are the ones that breed target spot.
The importance of scouting
The key to effective control is being proactive, and that begins with scouting. Target spot first appears in the lower canopy, with the circular lesions that give the disease its name.
“To effectively scout for target spot, growers are advised to get out into the middle of the field, in an area with little wind movement, if possible, and check under the canopy,” says John Schultz, BASF Technical Service Representative.
The disease can show up as early as July 1 in the Deep South; the timing is a week or two later farther north. It’s also a good idea to scout if there’s been a lot of rain and moisture.
Once the disease develops, it can spread and take over a field in just weeks. If lesions are visible, it means the fungus spores have already been attacking the plant for a week or more.
How a fungicide can help
Timing is critical when spraying. A soybean grower’s best bet is to spray before spotting the disease, typically around R3. Applying a fungicide around full flowering also allows it to get down into the lower canopy where the disease begins.
For cotton growers, a fungicide application during the first week of bloom will generally put growers ahead of the disease, Schultz said. He also recommends coming back with another application in the third week of bloom.
“I think Priaxor fungicide is an excellent tool for growers as the pressure of target spot continues to increase,” Schultz said.
Priaxor fungicide has been shown to provide the most consistent and reliable yield response. For a disease that can cause 50 to 80percent defoliation in a soybean field and wipe out 15 to 20 bu/A of yield, or eliminate 400 to 600 lb/A of lint yield in cotton, consistency can mean the difference between a good year and a bad one.
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