ETIOLOGY OF PEPPER WILT DISEASE OF ‘CHILE DE AGUA’ (Capsicum annuum L.) IN OAXACA, MÉXICO

Abstract

The causal agents of wilting disease in ‘Chile de agua’ plants (Capsicum annuum L.) were determined in Cuilapam de Guerrero, San Jerónimo Tlacochahuaya and San Sebastián Abasolo, Oaxaca, México. One hundred and twenty symptomatic plants were collected in the field from which 95 fungal isolates belonging to the genera: Alternaria, Fusarium, Macrophomina, Rhizoctonia, and Stemphylium, were obtained from 15, 19, 6, 38 and 17 samples, respectively. Also eight isolates of Phytophthora and seven of Pythium were obtained. Koch postulates were completed in vitro and under greenhouse conditions. In 5 days old seedlings inoculated in vitro, Fusarium lateritium, F. oxysporum, Macrophomina sp., Phytophthora capsici, Pythium sp., Rhizoctonia sp. (binucleate), and R. solani caused girdling and neck necrosis of roots (damping off) and death. In 45 days old plants inoculated under greenhouse conditions, the pathogenic isolates were P. capsici and R. solani. P. capsici caused wilting, neck necrosis of roots and stems without peeling of epidermis, and plant death 6 days after inoculation (dai). R. solani caused wilting with tempory recovery of turgescence, neck necrosis of roots and stems whit peeling of epidermis and girdling of secondary roots 30 dai.