Ag Alert Mar. 9, 2022

Researchers seek resistant varieties of strawberries

exoticdonorsandparents,”hesaid. “There is a high probability we will have resistant cultivars. The outlook is good.” While therearenovarietieswithverified resistanceamongcurrent varieties, Portola andPetalumaseemtoholdupbetterunder macrophomina pressure, whileMonterey andSanAndreas are highly susceptible. As methyl bromide was being phased out, Verticilliumwas thedisease thatmost concernedgrowersandresearchers, and it remains themost difficult. “Verticilliumisverycomplexgenetically,” Knappsaid. “We’retryingtopredict individ-

uals that will be highly resistant. Disease- resistant cultivars arepart of the solution.” While broccoli residue reduces the pathogen load, this disease survives in the soil forupto10yearsandcaninfect lettuce, making rotation a difficult strategy. Fumigationwithacombinationof chlo- ropicrin and Telone is a common strategy for conventional growers, while organic farmers can treat their infested soil with steamor anaerobic soil disinfestation. (Bob Johnson is a reporter in Monterey Coun t y . He may b e c on t a c t ed a t bjohn11135@gmail.com.)

Feed board looks to fill 3 openings TheCaliforniaDepartment of Food and Agriculture seeks to fill three vacancies on the Feed InspectionAdvisoryBoard. The panel makes recommendations to state agricultural officials on regula- tory and enforcement policies related to commercial feed inspections. The stated goal of the board is to support a clean and wholesome supply of milk, meat and eggs. Board vacancies are open to applicants whoholdacurrent Californiacommercial feed license. Board members serve three-year terms. They receive no financial com- pensation, but can be reimbursed for necessary travel expenses. Individuals interested in a board appointment must submit a resume and a completed Prospective Member Appointment Questionnaire, which are available on the CDFAwebsite. Applicants may email resumes and completed PMAQ paperwork to Brittnie. Williams@cdfa.ca.gov byMarch 31. ByBob Johnson UniversityofCalifornia,Davis, research- ers arewell on theway toward their goal of breeding strawberry varieties resistant to the crop’s major soil-borne diseases: fu- sariumwilt, macrophomina charcoal rot, verticilliumand phytophthora. Because thesediseasescanpersist inthe soil for three to10 years, resistant varieties are essential for control. The next varieties headed toward re- leasehaveresistance to fusarium, adisease that has been challenging to manage for many growers. “Wediscoveredsinglegeneresistance to fusariumrace1 in2016,” saidSteveKnapp, director of the strawberry breeding pro- gram at UC Davis. “It has been validated since then in the field.” Fusariumwiltcancauseplantstocollapse anddielateintheseason,andthepathogens can survive in the soil for up to three years. The disease tends to bemost severewhen warmerweather stresses theplants. Knapp made his remarks as he dis- cussedvarietybreedingduring theannual strawberry production researchmeeting held online in early February. “I’mguessingwewillputupthreevarieties forreleasebytheuniversitylaterthisyear,”he said. “All of themhave fusariumresistance, highyieldsandproduce fewrunners.” Whilevarietieswithresistance to fusari- umwilt race1arealreadyavailable, Knapp is on the lookout for shifts in the disease thatmay require further breedingwork. “About 25%of cultivars carry one of the resistance genes,” he said. “We are also looking at possible shifts in the disease so we can be ready.” Macrophomina crown rot is a second disease that became important as growers

moved away frommethyl bromide fumi- gation. Most uses were banned by 2005. The symptoms are similar to fusarium wilt,whichmakes laboratorydiagnosesan essential part of amanagement strategy. Work on resistant varieties ismore pre- liminary inmacrophomina thanfusarium, but Knapp is optimistic. “Wewereable to identify some resistant

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March 9, 2022 Ag Alert 19