Identification and Management of Leaf Spots in Cotton

by Heather Kelly, University of Tennessee

This year I have gotten more questions about leaf spots in cotton than any other.  It hasn’t always been clear which leaf spot is present, but the following resources can help identify and understand management options of leaf spots in cotton.

This season in cotton bacterial blight is the leading leaf spot culprit, but as canopies have been closed in some fields for over 2 weeks and have had good moisture, target spot might start showing up more often as well as other leaf spots. Use the resources below to identify what leaf spots you’re seeing and what the best management options are:

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Spotting and managing target spot

To hear first-hand from an expert about how to manage target spot and some results of research to help, tune in next Monday afternoon at 3 PM for Dr. Austin Hagan’s webinar on target spot. Click here to register.

From an article by Tyson Raper, University of Tennessee, in Cotton Grower

As the cotton specialist for the state of Tennessee, I am constantly on the lookout for potential issues that may impact Mid-South cotton production. Over the past several years, I have occasionally observed several “target spots,” or Corynespora leaf spots, on the lower leaves of rank cotton plants. Although the number of spots and number of affected leaves are typically low, many growers have asked if the disease might be able to cause the 200-400/lb lint per acre yield penalties reported along the Gulf coast. Continue reading

Researchers discover control for devastating disease in Texas vineyards

by Kathleen Phillips, Texas A&M AgriLife

A product that helped stop a 100-year-old battle with a cotton disease in Texas has been proven effective in stopping the same fungus from devastating vineyards, according to a Texas A&M AgriLife Research plant pathologist.

“There are a lot of vineyards in Texas, both established vineyards and new ones, that are losing vines to cotton root rot,” said Dr. David Appel, who led the research with graduate student Sheila McBride. “So essentially we took a compound that was approved for use on cotton in 2012 and put it into the vineyards. And after about four years of research, we are absolutely confident of the results we are getting in suppressing the disease on grapevines.” Continue reading

Scout for bacterial blight in High Plains Texas

In Southwest Farm Press

by Jason Woodward and Terry Wheeler, Texas A&M AgriLife

Bacterial blight, caused by Xanthomonas axonopodis pv.malvacearum, has been reported from most all cotton production regions around the world. The bacterium is capable of surviving saprophytically on infested crop residue. Dry arid conditions facilitate survival in soil from year to year.

Cotton plants are susceptible to infection at all growth stages; however, leaves and bolls are most commonly infected later in the growing season. Conditions that favor disease development consist of moderate temperatures and high humidity. Wounding of leaves by blowing sand or hail may lead to an increase in incidence of the disease. Sprinkler irrigation can increase spread of the pathogen.

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Early disease and nematode control key to crop management

In Southwest Farm Press

Jason Woodward covered a lot of ground in a short time — in less than an hour he touched on several cotton disease issues, discussed new options for controlling nematodes and offered some variety selection points.

The recent Red River Crops Conference in Childress, Texas, in its second year and sponsored by the Texas and Oklahoma Extension services, offered a full two days of timely information on crop production, legislation, and market outlooks.

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