Effect of phyto-extracts of neem (Azadirachta indica) and garlic (Allium sativum) on leaf spot disease of groundnut (Arachis hypogaea L.)

Abstract

A field experiment was conducted to investigate the effect of aqueous and ethanolic extracts of neem (Azadirachta indica A. JUSS) and garlic (Allium sativum L.) against Cercospora leaf spot (CLS) disease of groundnut (Arachis hypogaea L.). A split plot design using two exotic (“fleur” 11 var., 65-13 var.) and one local (village var.) variety of groundnut as the main factor and ten treatments comprising one negative control (sterile distilled water), one positive control (fungicide: spavozeb) and eight phyto-extracts replicated three times was applied. Treatments were applied to plots at 45, 60, 75 and 90 days after planting (DAP). Results showed that CLS disease incidence ranged between 66.67% and 88.89% at 65 DAP for 10% ethanolic extract of garlic and 20% aqueous extract of garlic, respectively. Disease severity was lowest for 20% ethanolic extracts of neem seeds (14.74%) and garlic bulb (14.99%) at 65 DAP. Yield obtained from treatments of ethanolic extracts of garlic (3.62 t ha−1) was significantly higher (p < 0.05) than the control (2.40 t ha−1) but comparable to the spavozeb treatment (3.09 t ha−1). Exotic varieties were more productive (3.13 and 3.43 t ha−1) than the more resistant local variety (2.67 t ha−1).

Keywords

• arachis hypogaea l.
• garlic
• neem
• incidence
• leaf spot disease
• severity
• yield