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- As difficult as water cutbacks are, they pale in comparison to the biggest challenge California cotton has faced in its 100-year history — Fusarium Race 4.
Aerial view of a field infected with Race 4.
Australians are looking at crop rotation with small grains and rice, but there has not been a lot of success, Hutmacher added. UC research has validated that inoculum levels can be reduced with rotation, but when susceptible varieties are planted back into a field with Race 4, the disease level will return quickly to damaging levels.
Fortunately, there are a few Race 4 resistant varieties available. Most are Pimas. Phytogen 800 and 802 RF and Deltapine 360 lead the pack. DP 385 RF and Phy 811 RF have looked promising in short-term trials.
Initially, Race 4 seemed to be confined to Pimas, but Upland/Acalas are also susceptible, and Hutmacher has greatly increased upland evaluations over the past three years. He identified several experimentals that showed high levels of resistance last season in his trials.
“Growers have some very good resistant Pima variety choices, and seed companies seem to be pretty aggressive in their efforts as well,” Hutmacher said. Ulloa has released four highly resistant cultivars this year, all Pima with hopefully some uplands to follow.
Race 4 came in for considerable discussion at the Beltwide Cotton Conference this year. “It was mostly pathologists comparing notes on what they have found,” Hutmacher explained. With new molecular marker technology, scientists are able to better segregate Fusarium races. Fortunately, Race 4 has not been found outside of California, nor has an Australian strain of a similar race been identified in the U.S.
Nevertheless, other areas of the Belt have reason to be concerned about Race 4. Logic says the likelihood of spread is good.
“Based on what we’ve seen in California, Race 4 can spread in a relatively short time,” he said, adding that a non-Race 4 Fusarium spread quickly between the lettuce production areas of the San Joaquin Valley, the Salinas Valley and the southwest Arizona desert vegetable production areas despite the lettuce industry’s rigorous equipment cleaning protocol.
California agriculture is often the leader in new things. Unfortunately, it’s the guinea pig for a pariah no one wants. “We are certainly gaining a lot of experience in Race 4,” that may come in handy if it spreads.
The stepped up research effort, Hutmacher said, is another example of the cotton industry being pro-active. “It’s all about identifying issues and stepping up to the plate in providing funding to address the problem,” he said.
Another example of that is the cotton growers association’s leadership in developing an uncomplicated test to determine if Race 4 is in a field.
Paul Clark, business development manager for Agdia, told growers at the association’s annual meeting his company has developed a simple test growers and PCAs can use to identify Race 4.
Agdia, based in Indiana, was founded in 1981 and has developed 200 tests to detect various plant pathogens.
Normally, it takes from 7 days to 7 weeks to get results back from a lab. The Agdia test takes 30 to 40 minutes and can be performed on a pickup tailgate.
Agdia sells a kit that allows growers to test tissue samples for Race 4 in a five-step process.
“It is very specific to Race 4,” Clark said.
The testing equipment comes with 8 test kits. The initial cost is about $500, which includes the equipment to analyze a sample. Packets for taking eight individual samples cost about $240.
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