Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2017
Publication Date: 10/1/2017
Citation: Janisiewicz, W.J., Evans, B.E., Takeda, F., Jurick II, W.M. 2017. First report of Monilinia fructicola causing postharvest decay of strawberries (Fragaria ananassa) in the United States. Plant Disease. 101(10):1823. https://doi.org/10.1094/PDIS-04-17-0507-PDN.
Interpretive Summary: Monilinia fructicola is a fungus causing brown rot on stone fruits before and after harvest world-wide and is economically very important because it can cause extensive losses. In early summer of 2016, signs of this fungus decay were observed on strawberry fruit harvested from organically grown plants in a high tunnel located in the middle of stone fruit orchard at the Appalachian Fruit Research Station in Kearneysville, West Virginia. The fungus developed structures that are typically observed on stone fruits. The fungus was isolated, purified and re-inoculated to strawberry fruit and, after a few days in incubation, again caused the same signs of decay as observed earlier. Genetic analysis of the fungus confirmed that it is M. fructicola. This is the first report of any Monilinia fungus causing postharvest fruit decay of strawberry fruit in the United States.
Technical Abstract: Monilinia fructicola is a world-wide economically important pathogen of stone fruits causing brown rot before and after harvest. In early summer of 2016, signs of Monilinia spp. decay were observed on strawberry fruit, harvested from organically grown plants in a high tunnel located in the middle of stone and pome fruit orchards at the Appalachian Fruit Research Station in Kearneysville, West Virginia. The harvested, asymptomatic strawberries, were incubated on metal screens in plastic boxes for decay evaluation after 5 days at which time abundant production of sporodochia was observed. These sporodochia were used for isolation of the fungus, and three isolates designated WV-Str A, WV-Str B and WV-Str C were single–spore purified. All three isolates exhibited the same morphotype and produced a blackish rubbery mycelial mat on Peach agar medium (PA). WV-Str B was selected for further studies. It produced distinct colonies on PDA and Oatmeal Agar (OA) and grew slower than WV-Mf 7 on PA and comparably on PDA and OA. Koch’s postulates were conducted and confirmed pathogenicity of the isolates to strawberry fruit. Genetic identification, using Mon 139-F and Mon 139-R primers resulted in 100% match to M. fructicola with e-value near zero using BLAST. To our knowledge this is the first report of any Monilinia spp. causing postharvest fruit decay of strawberry fruit in the United States.