Charcoal Rot of Strawberry Producton Guideline by Steven T. Koike, Thomas R. Gordon, Oleg Daugovish, Husein Ajwa & Frank Martn Introduction and signifcance Beginning in 2005, strawberry growers in southern California reported an increasing problem with collapsing strawberry plants. Te fungus Macrophomina phaseolina was consistently associated with these problems. Te disease is called charcoal rot. Virtually all of the initial outbreaks were associated with felds that no longer were fat- fumigated with methyl bromide + chloropicrin that was shank injected under plastic tarp. Initially documented in Orange and Ventura counties, the disease in subsequent years was found in Santa Barbara and San Luis Obispo counties and then later in the central coast region (Monterey, Santa Cruz, and Santa Clara counties). Charcoal rot has also been found on strawberry in various other parts of California (San Diego, Alameda, Yolo, and Sacramento counties). Charcoal rot is economically important and over time can afect the majority of the strawberry plants in a feld (Figure 1). Symptoms Initial symptoms of charcoal rot in strawberry usually occur afer the plants are well established and begin to produce fruit: the older leaves wilt, turn gray green in color, and begin to dry up (Figure 2). Issue 10 November 2013 Figure 1. In severe cases, charcoal rot can afect large portions of a feld. Te California Strawberry Commission Production Guidelines are produced in cooperation with scientists who conduct research related to strawberry production. Tese guidelines are a tool for growers, providing critical scientifc background information on diseases and pests common to strawberry production in California. For copies of this guideline or others in the series, visit www.calstrawberry.com. Production Guideline by: Steven T. Koike UCCE Monterey County stkoike@ucdavis.edu p. 831.759.7350 Tomas R. Gordon University of California, Davis trgordon@ucdavis.edu p. 530.754.9893 Oleg Daugovich UCCE Ventura County odaugovish@ucdavis.edu p. 805.645.1454 Husein Ajwa University of California, Davis haajwa@ucdavis.edu p. 831.755.2823 Frank Martin USDA-ARS fmartin@pw.ars.usda.gov p. 831.755.2873 © 2013 California Strawberry Commission Figure 2. Initial symptoms of charcoal rot consist of wilted leaves that become dull green or gray in color. ®