Management of leaf spot in groundnut
GROUNDNUT IS cultivated all over the country. India stands second in production of this commercial oilseed crop.
Majority of the area under growth is rain fed. Continuous droughts coupled with attack by a variety of diseases and insect pests have limited the production of groundnut.
Different types
More than 57 types of infestations have been found affecting groundnut. Among them early and late leaf spot infestation are economically important.
Early leaf spot is prevalent in all 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 spots usually bear a light to dark brown centre and a yellow halo. The lesions are also found on the petioles and stems.
In severe cases of infestations shedding of the leaflets occurs. 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.
Temperature ranging from 25 to 30{+o}C, moisture hours and high humidity favour this infection's spread.
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 pearlmillet or sorghum with groundnut (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 3 times starting from 4 weeks of sowing or Carbendazim (0.05 per cent) + Mancozeb (0.2 per cent) at 2 - 3 weeks interval 2 or 3 times starting from the initiation of the disease will check the spread of this disease.
Mallikarjun Kenganal
Hemavati Ranebennur
& Byadgi, A.S.
Department of Plant Pathology
University of Agricultural Sciences, Dharwad
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