Experts agree that the key to turning back Fusarium Race 4 is the development of more, higher resistant varieties. That is why the closure of Shafter and the apparent departure of Ulloa are particularly disappointing. Ulloa has made significant progress toward identifying Fusarium Race 4 resistant genetics.

UC has screened both existing Pima and Acala varieties for susceptibility to Race 4. Initially, most believed Race 4 would only impact Pima. However, that has proven incorrect as the fungal inoculum has magnified in field and Acala varieties are considered susceptible. The UC cotton management website: http://cottoninfo.ucdavis.edu/pubs.htm contains fusarium variety screening trials to help growers select varieties for Race 4 infected fields.

Planting highly susceptible varieties in infected fields is a virtual guarantee that Race 4 will spread rapidly.

A grower might get away with planting a susceptible Acala or Pima for a one or two seasons in lightly infected fields, but eventually Race 4could render the field unable to produce cotton. Several growers have already red-lined fields for cotton because of high Race 4 inoculum levels.

Hutmacher said the most tolerant and most susceptible Pima varieties are Pimas with Acalas “somewhere in between” the Pima range.

PhytoGen 800 has been a lifesaver in the Race 4 challenge. It is the most resistant variety available. The new PhotGen 802RF is right up there with 800 on resistance. However, Dow AgroSciences rep Harry Peck said the Roundup Flex variety will be on “allocated,” limited supply in 2012. 800 planting seed should be plentiful, he added.

Until more resistant varieties are developed, Hutmacher said the first line of defense is to reduce Race 4 inoculum.

The first step is to monitor for the diseases. UC and the grower organization have developed an excellent brochure on what to look for in scouting for fusarium. It is available at http://cottoninfo.ucdavis.edu/IMAGES/Fusarium.pdf.

Sampling for Race 4 in cotton row skips or sickly plants is the first place to check for fusarium. Hutmacher recommends killing any surviving, weak plants, even if they hold the potential for setting cotton.