Bacterial blight is like that really bad case of the flu you had one time years ago: It doesn’t happen often — but you never forgot it. In cotton, it can be just that bad.
It is an opportunistic plant disease in cotton, says Jason Woodward, Texas A&M AgriLife Extension pathologist at Lubbock. “The pathogen has been reported in every country where cotton is grown,” he said at the Red River Crops Conference at Childress, Texas.
“No matter where you go in the High Plains or the Rolling Plains of Texas, you see it somewhere, even in 2011.” Recent reports also indicate frequent and somewhat widespread occurrences in Oklahoma.
Losses can be significant — from 35 percent to 59 percent in field epidemics reported in the late 1950s (before use of acid-delinted seed), Woodward says. “Currently, negligible losses have occurred; however, sporadic outbreaks do occur (they have been more frequent recently).”
The pathogen thrives under high moisture, high heat, and high humidity environmental conditions. It is specific to cotton, and may persist in field debris for a limited time or survive on seed. Cotton is susceptible throughout the growing season, and infections may occur on foliage and bolls.
DAMAGE INCREASES SUSCEPTIBILITY
“If the plant is damaged, it’s possible infection may take place more easily,” Woodward says. Blowing sand, hail, insects feeding on bolls, even herbicide injury, may make the plant more susceptible to bacterial blight.
“If you had the disease last year, there is a good chance it will show up this year. But weather plays a significant role. The pathogen can survive in arid conditions, but disease development is highly dependent on environmental conditions; high humidity is required for infection.” A dense canopy and rainfall, or high irrigation capacity, can also create favorable conditions for infection.
“We saw a lot of acres infected across the region last year, a result of the prevalence of susceptible varieties and conditions favorable for development of bacterial blight. In Texas, we typically see the disease late in the season.”