When a joint public-private partnership launched the Yuma Center of Excellence for Desert Agriculture (YCEDA) 2.5 years ago, collaborating growers and the University of Arizona (UA) decided it’s No. 1 priority was to identify more management techniques for Fusarium wilt disease of lettuce (FWOL).
With more and more acreage infected with the FWOL pathogen - Fusarium oxysporum f.sp. lactucae, growers are increasingly losing pathogen-free acres to grow these core vegetables for consumers.
Brierley says, “Fusarium wilt is boxing growers into a corner, keeping them from meeting market demand at certain times of the year.”
In California, FWOL is found primarily in Fresno County, and also in coastal Monterey and Santa Cruz counties, plus southeastern Imperial County. It’s also found in Arizona’s vegetable-growing areas including Yuma County.
Over the last two years, pathologists have conducted grower field trials, analyzing improved cultivars and evaluating crop protection materials to reduce the incidence and severity of Fusarium wilt.
On the cultivar side, grower field trials conducted in 2015 and 2016 determined that current romaine lettuce varieties on the market are generally more resistant than their sister crisphead varieties. In romaine, the Del Sol and Duquesne varieties scored higher in FWOL resistance while the Oracle and Meridian cultivars scored higher resistance in crisphead.
