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- Fusarium Race 4 has been around awhile, but with the expanded cotton acreage this season it has been found in far more areas than ever before. It has been identified in all six SJV cotton-producing counties in more than 200 total locations.
Cannon Michael, chairman of California Cotton Growers Association.
Hutmacher called Race 4 an opportunistic pathogen “that stays in the soil waiting for you to plant a susceptible variety.” Under ideal environmental conditions for it, Race 4 can explode and this was the year for it because of late, wet planting conditions that stressed seedling cotton.
Conversely, wise management decisions to avoid those conditions could put growers in a better position to ward off the menace.
This includes first planting a tolerant variety. “The higher the resistance; the better,” Hutmacher urged.
“Planting dates are critical. Generally, the warmer the conditions where the plant’s root system can grow rapidly, the fewer pathogens will attack it. You don’t want to play into this disease’s hands. We remind growers that this is an early-season disease,” Hutmacher added.
Anything that makes a plant struggle early may weaken it and make it susceptible to Race 4, Hutmacher said.
“One of the problems with Race 4 is that it can survive nicely on a wide collection of plants and weeds without infecting those plants or weeds. The pathogen lives on root surfaces and can persist for years. It will not go away,” Hutmacher said.
The cotton Extension specialist praised PCAs and many growers for being alert to the problem this year and identifying suspect areas to be tested.
Heretofore, Race 4 has been a California problem, although suspect races have been found in at least two Southern states, including Alabama and Louisiana.
“One of the interesting things (UC plant pathologist) Mike Davis has found using newer biotech approaches to more quickly identify disease is that other races in Southern states look pretty scary — a lot worse than Race 4. And they do not need nematodes to spread,” said Hutmacher.
This heightens the need to continue screening for soil borne pathogens as well as to focus on developing disease-resistant new varieties.