Dioscorea hispida: potential botanical for the control of cassava scale insect

• Published in: Philippine Journal of Crop Science (Philippines) Vol. 16; no. 1
• Main Authors: Vasquez, E.A, Platino, Ma. G. (Visayas State Coll. of Agriculture, Baybay, Leyte (Philippines). Philippine Root Crop Research and Training Center)
• Format: Journal Article
• Language: English
• Published: 01.11.1991
• Subjects: CONTROL DE PLAGAS; DIOSCOREA HISPIDA; LUTTE ANTIRAVAGEUR; MANIHOT ESCULENTA; PSEUDAULACASPIS PENTAGONA
• ISSN: 0115-463X

Crude extracts were prepared from several plant species previously reported as having pesticidal activities. They were used in the preplanting treatment of cassava cuttings to substitute commercial pesticides used against Pseudaulacaspis pentagona, the scale insect attacking cassava stem. Among the plant extracts evaluated and bioassayed, the water-based crude extract of Asiatic bitter yam, Dioscorea hispida, was found most effective against cassava scale insect at 5.0 percent concentration and 12-24 hours soaking period. Field evaluation of the effectiveness of D. hispida extract against known commercial insecticides like malathion and dimethoate in controlling scale insect infestation showed comparable results. The treated plants were kept scale-free within 6 months after planting (MAP) while the untreated ones became infested as early as 1 MAP. Germination of chemically-treated cassava especially those treated with malathion was significantly lower than the D. hispida - treated and untreated ones. Although not much significant difference was observed between yields in both treatments, those treated with D. hispida gave higher cost and return values