Internal fruit rot caused by Fusarium subglutinans in greenhouse sweet peppers

Experiments were conducted to isolate the causal organism of internal fruit rot in greenhouse sweet pepper (Capsicum annum), confirm its identity, and elucidate its transmission mode and host range. The effects of inoculum concentration, growth stage of the plant, and cultivar of sweet pepper on disease development were also determined. The causal organism was identified as Fusarium subglutinans. Inoculum concentrations of 10(4) to 10(6) conidia/mL resulted in a higher incidence of fruit infection compared with 10(3) conidia/mL when just-opened and fully opened flowers were inoculated. Inoculation of flowers at different stages with F. subglutinans resulted in more diseased fruits than fruit inoculations. None of the seeds from infected pepper fruits germinated, and 92% of those yielded typical F. subglutinans colonies. No evidence of root infection of pepper plants by F. subglutinans was observed, and no disease developed on fruits of greenhouse tomato, cucumber, or eggplant. Fruits of Capsicum annuum 'Bison' and 'Mazurka' were less susceptible to F. subglutinans than those of 'Sympathy' and '444'.