Response of cucumber cultivars to target spot based on epidemiological components of the disease monocycle

Author(s)

Fischer, Ivan Herman ; da Silva, Lucas Meleiro ; Amorim, Lilian ; Galli, Juliana Altafin ; Parisi, Marise Cagnin Martins

• Document type: Journal article
• Source: JOURNAL OF PHYTOPATHOLOGY; v. 169, n. 7-8, p. 10-pg., 2021-04-08.

Abstract

Corynespora cassiicola is the causal agent of target spot of several cultivated species, among which cucumber is highlighted for frequent reports of yield losses under greenhouse conditions. Given the difficulties managing this disease due to the lack of information about the resistance of cucumber cultivars, the aim of the present study was to evaluate the response of ten cucumber cultivars to C. cassiicola based on epidemiological components of the disease in a greenhouse. Symptoms of target spot were apparent in all cucumber cultivars from the second day of inoculation of C. cassiicola, demonstrating the short incubation period of the disease and the susceptibility of the crop. The components latent period, number of lesions, lesion diameter, disease severity, number of sporulating lesions, number of spores per affected leaf area and number of spores per sporulating lesion varied according to the cucumber cultivar. The monomolecular model showed the best fit to the number of target spot lesions during the ten days of evaluation, showing differences between cultivars for initial inoculum and disease progression rate parameters. Multivariate analysis with the epidemiological components combined identified three groups of cultivars: one group that was less affected by the disease, represented by Safira and Diplomata cultivars; a second group showing intermediate behaviour, including Valent, Eureka, Taiko, Yamarashi and Darlington cvs., and a third group that was most susceptible to the pathogen and was represented by Soldier, Vulcano and Exocet cvs. Safira and Diplomata cultivars showed low level of susceptibility to target spot and can be recommended for areas with high disease intensity. (AU)

• FAPESP's process: 18/02966-3 - Cucumber (Cucumis sativus L.) target spot: epidemiological aspects and control
• Grantee: Ivan Herman Fischer
• Support Opportunities: Regular Research Grants