Preventive and Curative Effects of Treatments to Manage Strawberry Root and Crown Rot Caused by Neopestalotiopsis rosae

Abstract

Strawberry root and crown rot caused by the fungus Neopestalotiopsis rosae is an emerging disease that has caused yield losses reaching 70% in Mexico and other regions worldwide. This research evaluated the effects of biological and chemical fungicides applied as preventive and curative applications for controlling root and crown rot caused by N. rosae in strawberries under greenhouse conditions. Treatments included these chemical fungicides: prochloraz, prochloraz+thiram, cyprodinil+fludioxonil, difenoconazole+azoxystrobin, iprodione, captan, thiram, pydiflumetofen+fludioxonil, fluxapyroxad+pyraclostrobin, and hymexazol; each applied at commercial doses. Also tested were biological treatments based on Trichoderma koningiopsis, Trichoderma asperellum, Streptomyces sp., and Bacillus amyloliquefaciens strain D747 (B. velezensis). Disease incidence, severity, plant mortality, root length, and dry weight were determined. Results showed that overall, preventive applications of the fungicides pydiflumetofen+fludioxonil, cyprodinil+fludioxonil, and prochloraz resulted in the smallest area under the disease progress curve, and lowest final disease incidence, severity, and plant mortality. An intermediate group of effective treatments entailed hymexazol, iprodione, T. asperellum, and T. koningiopsis (50–75% efficacy). Treatments with greater efficacy (99 to 100%), prochloraz pydiflumetofen+fludioxonil, cyprodinil+fludioxonil, and prochloraz, also had maximal total plant biomass vis-à-vis the untreated control. In contrast, each treatment’s efficacy was significantly reduced when applied curatively (0 to 37% treatment efficacy). These results suggest that certain treatments are useful for controlling strawberry root and crown rot caused by N. rosae, when applied preventively (as root dipping). These results will contribute to design more effective management programs of root rot and crown rot caused by N. rosae on strawberry.