Diseases commonly affecting vegetables in Eastern Visayas, Philippines, and their incidence under protective structure and in the open field

Year-round production of vegetables in the Eastern Visayas region of the Philippines is challenging due to high rainfalls. Gonzaga et al. (2013) confirmed the feasibility of producing vegetables under low-cost protected structures that produced significantly higher yields compared to crops grown in the open field. One major reason for this was the difference in the incidence of diseases between these two conditions. Regular disease monitoring were conducted in vegetable fields at Visayas State University and Ormoc City, Leyte, and Maasin City and Bontoc, Southern Leyte from 2010 to 2012 to compare the occurrence and incidence of common diseases affecting vegetables under protective structure and open field. The kinds of diseases, incidence and disease severity were documented. The most commonly recorded diseases were downy mildew caused by Pseudoperonospora cubensis affecting bitter gourd, cucumber and squash; Cercospora leafspots/leaf moulds affecting tomato, sweet pepper, bitter gourd and snap beans; bacterial wilt caused by Ralstonia solanacearum that affected solanaceous and few cucurbits; and bacterial spots caused by Xanthomonas vesicatoria. The incidence of fungal and bacterial diseases was generally lower under protective structure than in the open field. There were farms where a particular disease (e.g., bacterial spot) occurred only in the open field but not under structure or that occurred only under structure (e.g., sooty mould) but not in the open field. Sooty moulds were more common under protective structure and this finding was related to the presence of honeydew-producing insects. The incidence of virus diseases had no pattern.