Managing leaf spot disease of groundnut
GROUNDNUT IS cultivated all over the country. India stands second in the production of this commercial oilseed crop. Majority of the area grown is under rain fed.
Continuous droughts coupled with attack by a variety of diseases and insect pests have limited the production of groundnut.
Important infestations
More than 57 types of infestations have been found in groundnut. Among them early and late leaf spot infestations are economically important.
Early leaf spot is prevalent in the entire groundnut growing areas. Infected leaves shows lesions of circular shape.
Dark brown lesions
On the upper surface of the leaves, the lesions appear dark brown, with sporulation, while on the lower surface, they appear light brown.
The lesions are also found on the petioles and stems.
In severe cases of infestations shedding of the leaflets occur. Moisture and high humidity favour the spread of this infection. The late leaf spot causes brown to black, circular lesions on the lower surface of the leaflet.
Pest management
— Burying of the crop residues in the soil, and removal of volunteer groundnut plants are important measures.
— Use of resistant or tolerant varieties.
— Intercropping with pearl millet or sorghum in the ratio(1:3) is useful.
— Foliar application of aqueous neem leaf extract (5 per cent) or 5 per cent neem seed kernel extract at 2 weeks interval for 3 times starting from 4 weeks of sowing or Carbendazim (0.05 per cent) + Mancozeb (0.2 per cent) at 2-3 weeks interval for 2 or 3 times starting from the initiation of the disease.
MALLIKARJUN KENGANAL HEMAVATI RANEBENNUR & A.S. BYADGI
Department of Plant Pathology
University of Agricultural Sciences, Dharwad
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