Taro Diseases

Abstract

Although taro is susceptible to attack by at least twenty-three pathogens, only a few cause serious reduction in growth and production. Phytophthora blight (Phytophthora colocasiae) and Pythium root and corm rot (Pythium spp.) are the most serious fungal diseases of taro. Phytophthora blight is not yet found in Samoa, the Marquesas, the Society and Cook Islands. Dithane-M45 is available for control of Phytophthora blight. Pythium root and corm rot is found where ever taro is grown. Five Pythium spp. have been implicated as causal agents of the disease. Captan provides good control of the disease. Data to apply for metalaxyl registration on taro for control of Pythium root and corm rots are being collected. Phyllosticta leaf spot (Phyllosticta colocasiophila), Sclerotium blight (Sclerotium rolfsii), Black rot(Ceratocystis fimbriata), Rhizopus rot (Rhizopus stolonifer), Phytophthora root rot (P. palmivora) and Fusarium dry rot (Fusarium solani) are other fungal diseases which may be locally important. Hard rot (unknown etiology) is a major problem in wetland taro culture where it can cause substantial losses. Erwinia spp. may cause bacterial soft rots. Root-knot nematodes (Meloidogyne spp.) cause root galls and corm malformations.