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Rain, cool temps increase cotton diseases

Shelley E. Huguley swfp-shelley-huguley-monclova.jpg
Texas A&M AgriLife Research and Extension Plant Pathologist Cecilia Monclova discusses plant diseases and the transmission of FOV4 through infected Pima cottonseed at a field day at the Texas A&M AgriLife Research and Extension Center, Halfway,
Plant Pathologist discusses FOV4, urges caution.

When it comes to treating diseases in cotton, chemical treatments are the only option.

"There are no varieties available to protect for seedling diseases," said Plant Pathologist Cecilia Monclova, who has a joint appointment with Texas A&M AgriLife Research and Extension and Texas Tech University, Lubbock.

swfp-shelley-huguley-monclova-headshot-web.jpgPlant Pathologist Cecilia Monclova (Photo by Shelley E. Huguley)

"When we're talking about seedling diseases, we're talking about everything that is in the soil that can cause some early stand losses," Monclova explained. "They will usually happen 14 to 28 days into the season."

But what can help reduce pathogens are seed treatments. Monclova said seed treatments protect the seedling until it's old enough to protect itself. 

Monclova discussed the importance of seed treatments and two primary diseases producers are facing this year, and FOV4, following a recent field day at the Halfway Texas A&M AgriLife Research and Extension Center. 

Ideal conditions 

Since the end of May, producers on the Texas Plains have received long-awaited rainfall coupled with unseasonably cool temperatures – a relief to the drought-stricken area and ideal conditions for pathogens.

"Farmers might be pulling out their hair saying, 'What is going on?' because they haven't seen it in so long, but the rain and the temperature were simply perfect for the diseases," Monclova said.  "I know a few farmers in Terry County, who lost their crop due to diseases early in the season, particularly the ones that are under pivot. The irrigated crop tends to have higher disease pressure compared to the dryland."

Primary diseases

Monclova said when it comes to diseases, a cotton plant can have a disease complex where it's infected by multiple pathogens. But the primary disease area growers are facing is Rhizoctonia, also known as "rhizoc" she said.

"Rhizoctonia is common every year but this year it was simply perfect, enough water, cool temperatures and it (the disease) burst and killed many cotton seedlings," she said. 

The number two disease is Fusarium, a pathogen Monclova said has multiple species. "Even when you have Rhizoctonia and then you add Fusarium to the mixture, it will exacerbate the damages. Some people might say, 'Hey, I controlled Fusarium, so what is going on?' You might have more than one player in the system. That's why seedling treatments are like a cocktail of different products, so you can control multiple pathogens at the same time."

Variety testing

Monclova and the team of Extension plant pathologists conduct variety testing trials each year, specifically for diseases that appear later in the season.

Trial results are available at the Lubbock Texas A&M AgriLife Research and Extension Center website. "You can go in and see the different varieties, how they perform, the yield potential and also the fiber quality. Because when we talk about later-season diseases, variety selection is key because the seed treatment will not protect you for more than 28 days," Monclova said.

Watch this video to hear what Monclova had to say. 

Raising awareness

A disease that hasn't arrived to the Texas Plains but could be threat to the 3.6 million acres of cotton grown in the area, is FOV4, fusarium wilt race 4. Traditionally, producers on the Texas Plains have produced Upland cotton but in recent years more Pima varieties have been planted, raising concerns about the transmission of FOV4.

"We have fusarium wilt here but only race 1 and 2. We don't have FOV4, but it has been reported in El Paso about five years ago," she said. 

Both Pima and Upland cotton are susceptible. The pathogen is detrimental to cotton because of its multiple stages. "For example, when we talk about seedling diseases, you will see the damage early in the season and then whatever survives, you're off the hook."

FOV4 has a second wave.  "Early in the season, FOV4 does not require any other player to cause diseases -- does not need nematodes, does not need Rhizoctonia or anything else to cause the symptoms," Monclova explained.

Within the first 21 days, some seedlings will die. "It will look like it was burned," she said. Stand loss can be as high as 50%. Then two weeks later, 100%, when a susceptible variety is planted in a highly infested field,” Monclova said. 

"Whatever survives, will get the later onset of the disease which causes wilting symptoms."

Disease transmission

FOV4 is aggressive and because it infects the seed, Monclova recommended the following:

  1. Source your seed. Do not purchase seed from locations previously infected by FOV4, i.e, California, El Paso, and some places in New Mexico.
  2. Everywhere the infected soil goes, the fungus can go. "It lives in the soil," she said. FOV4 can be spread via equipment, bottom of boots and/or truck tires. "Everything that can carry that soil across county lines is a potential spreader."

To learn more about FOV4 and its symptoms and how it is transmitted, watch the following videos: 

 

 

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