Not only is turning back Race 4 critical to lint production in the valley, it could also have a devastating impact on an important element of the valley’s cotton industry — seed production.

Premium certified cotton planting seed is produced in the valley for varieties sold not only within the valley, but elsewhere in the U.S. and world. Michael said it is critical to protect that part of the state’s cotton industry.

The first line-of-defense against the spread of Race 4 is planting resistant varieties and avoiding susceptible ones. Race 4 is particularly lethal to Pima. Fortunately, phytogen 800, the most widely planted Pima in the valley, is highly resistant. Deltapine 744 Pima is highly susceptible, but is not grown any more. Pima 830 is susceptible at high Race 4 inoculum levels. Phytogen 802RF appears to be tolerant. Phytogen 805 Pima was thought to have good tolerance, but it broke down this year under high Race 4 inoculum levels.

Acalas at one time were not thought to be susceptible to Race 4, but that is no longer the case. Bob Hutmacher, University of California Extension cotton specialist, said he has seen high plant stand losses to Race 4 in Phytogen 725, Phytogen 755 and Daytona.

“It is unusual to see a field wipeout, but stand losses of 30, 40 or 50 percent can happen. I have seen half a dozen fields this year with stand losses of greater than 50 percent in Acala by mid-squaring without a susceptible Pima,” said Hutmacher.

The inoculum levels may be initially low in a field, but can spread rapidly with the planting of a highly susceptible variety.

The UC cotton website has a wide range of information about recognition and containment of Fusarium. Go to http://cottoninfo.ucdavis.edu/.

CCGA President Earl Williams said the ultimate solution to the problem is development of more resistant Acala and Pima varieties, but that is at least five to 10 years away in the best scenario. In the meantime, growers must educate themselves on what to do to stem the spread of Race 4.

Williams said research money will be directed at chemical and field treatments. Soil solarization is a possible option, but it is an expensive one and can likely be used on small acreage. Seed treatment and using injected steam to kill the organism are other possible ways to combat Race 4 spread.