Managing no-till or reduced-till cotton production properly, including following appropriate planting recommendations and taking care of early weed problems, may reduce potential for disease outbreaks.
Reduced tillage systems offer growers opportunities to conserve soil, preserve moisture and reduce some operating costs, says Louisiana State University Extension weed specialist Boyd Padgett. But the environment that makes reduced-tillage effective also provides an ideal host for some cotton diseases.
Padgett, speaking at the annual Cotton Consultant’s Conference during the Beltwide Cotton Conferences recently in New Orleans, said farmers should pay attention to early season weed control and select the proper burndown herbicides to remove alternate disease hosts that harbor numerous damaging pathogens.
“Tillage has an effect on some cotton diseases,” Padgett said. He said seedling disease development depends on several factors, including cultural practices, weather and field history. “But field history may play less of a role than we once thought.”
He said organic matter is higher in reduced-till systems and that organic matter serves as a host to some disease organisms. “Plant residue plays a key role in pathogen survival. Volunteer plants and weeds also serve as pathogen hosts.”
He said the first line of defense is to plant high quality seed, at least 80 percent germination and at least 60 percent cold germination ratings.
He said soil moisture and temperature also affect disease development. Reduced-till systems typically conserve more moisture but warm up slower in the spring. He recommends planting in the most favorable environment possible to reduce potential for disease and to achieve the best plant establishment. “Make certain soil temperature is at least 65 degrees Fahrenheit for four to five consecutive days with no threat of rain before planting,” he said.
Seed treatments also help, he said, but do not provide as much residual activity as in-furrow treatments.
Crop rotation, he said, is important to prevent nematodes in reduced-till systems.
Knowing soil types also helps. “Sandy soils favor Fusarium and plant residues serve as a food source for organisms.”
Identifying and controlling host plants should be part of the process, too. “Verticillium has more than 400 hosts; other pathogens have as many as 2,000. Controlling those host plants early with burndown herbicides may reduce potential for the diseases to develop, even though burndown herbicides have minimal impact on most diseases. He said some products, however, may injure seedling cotton and make them more susceptible to disease infection.
Padgett said reduced tillage offers advantages for managing diseases in seedling cotton. “We don’t have redistribution of pathogens across the field with cultivation,” he said. “We don’t move nematodes and other problems from one field to another on tillage equipment. We get less crusting in reduced-till soils so we get better emergence.”