Postharvest incidence of stem end rot in 'Hayward' kiwifruit is related to preharvest Botrytis cinerea colonization of floral parts and latent infection

Stem end rot (SER) caused by Botrytis cinerea is the most important postharvest disease in the Chilean kiwifruit industry. Relationships between the postharvest occurrence of SER in Hayward kiwifruit and the temporal dynamics of earlier B. cinerea colonization of the floral parts (petals, sepals, receptacles, styles) was studied in five orchards over two consecutive seasons in Chile. Weather conditions in the first season favored B. cinerea infection with roughly constant colonization of floral parts up to about 120 days after full bloom but colonization then increased up until harvest. In the second season colonization was roughly constant throughout. Latent infections of the fruit occurred in both seasons but were high in the first season and low in the second. Incidence of latent infections at harvest were the best predictors (r>0.8) of postharvest SER. The number of preharvest infection periods calculated using temperature, leaf wetness and relative humidity satisfactorily predicted SER incidence by an exponential model, R2 = 0.90, P<0.001. Results indicate environmental variables play key roles in the temporal dynamics of B. cinerea colonization. Quantification of latent B. cinerea infections in asymptomatic fruit close to harvest is a practicable way to predict later incidence of SER during storage.SourcesPostharvest incidence of stem end rot in 'Hayward' kiwifruit is related to preharvest Botrytis cinerea colonization of floral parts and latent infectionDanae Riquelme, Hector Valdes, Marc Fermaud, and Juan Pablo ZoffoliPublished Online:1 Oct 2019, APS Publications, Plant Disease, https://doi.org/10.1094/PDIS-06-19-1315-REPicture by Elmercurio.com