Infection pathway of Botrytis cinerea in capsicum fruit (Capsicum annuum L.)

Abstract

Botrytis cinerea, which causes grey mould, infects fruit of a number of horticultural crops during their development but then remains latent until the ripening process when the disease manifests. However, how B. cinerea grows in capsicum fruit after harvest has not been fully characterised. The present research has examined the growth of B. cinerea in fruit of two cultivars of capsicum (cv. Aries and cv. Papri Queen) that were inoculated either before or after harvest. Three concentrations of conidial suspensions (10⁴, 10⁵ and 10⁶ conidia mL⁻¹) were used to inoculate flowers at three preharvest stages – anthesis, 3 days after anthesis (DAA) and 6 DAA, and fruit at three postharvest ripening stages – deep green (DG), breaker red (BR) and red (R). Inoculation with water served as a control. Rot development was then monitored daily during postharvest storage at 10 °C by measuring the length and width of lesions. Cv. Aries was more susceptible to B. cinerea than cv. Papri Queen regardless of whether inoculation occurred preharvest or postharvest. Flowers often died when inoculated at anthesis. Regardless of cultivar, as inoculum concentration increased the number of flowers that died also increased. However, disease development on fruit was not affected by inoculum concentration or the timing of inoculation before harvest. When fruit were inoculated after harvest, grey mould developed most rapidly in BR fruit of cv. Papri Queen and in R fruit of cv. Aries. The understanding of infection of B. cinerea revealed by this research and its implications for disease management are discussed.