Groundnut is one of the most important oilseed crops in India.For the good production and high yielding of Groundnut, the crop should be protected from the attack of various pests and diseases.Major Groundnut Diseases are:-
1.Groundnut Early leaf spot: Cercospora arachidicola
Symptom:
- The infection starts about a month after sowing.
- Small chlorotic spots appear on leaflets, with time they enlarge and turn brown to black and assume sub circular shape on upper leaf surface.
- On the lower surface of leaves light, brown colouration is seen.
- Lesions also appear on petioles, stems, stipules.
- In severe cases several lesions coalesce and result in premature senescence.
Management:
Spray any one of the following:
- Carbendazim 500 g/ha
- Mancozeb 1000 g/ha
- Chlorothalonil 1000 g/ha
If necessary give the second round 15 days later. Combined infection of rust and Leaf spot
Spray any one of the following:
- Spray 10% Calotropis leaf extract
- Spray Carbendazim 250 g + Mancozeb 1000g/ha
- Chlorothalonil 1000g/ha. If necessary give the 171 second round 15 days later.
2.Groundnut Late leaf spot: Phaeoisariopsis personatum
Symptom:
- The infection starts around 55-57 days after sowing in Kharif and 42-46 days after sowing in Rabi.
- Black & nearly circular spots appear on the lower surface of the leaflets.
- Lesions are rough in appearance. In extreme cases, many lesions coalesce resulting in premature senescence and shedding of the leaflets.
Management:
- Intercropping pearl millet or sorghum with groundnut (1 : 3) is useful in reducing the intensity of late leafspot.
- Crop rotation with non-host crops preferably cereals.
- Deep burying of crop residues in the soil, removal of volunteer groundnut plants are important measures in reducing the primary source of infection.
- Spray Carbendazim 0.1% or Mancozeb 0.2% or Chlorothalonil 0.2%.
3.Groundnut Rust: Puccinia arachidis
Symptom:
- Pustules appear first on the lower surface and in highly susceptible cultivars the original pustules may be surrounded by colonies of secondary pustules.
- Pustules may also appear on the upper surface of the leaflet.
- They may be formed on all aerial plant parts apart from flower and pegs. Severely infected leaves turn necrotic and desiccate but are attached to the plant.
Management:
Spray any one of the following:
- Mancozeb 1000g /ha
- Chlorothalonil 1000g /ha
- Wettable sulphur 2500g /ha
- Tridemorph 500 ml/ha
- If necessary, repeat the spray 15 days later.
4.Groundnut Stem rot: Sclerotium rolfsii
Symptom:
- Pustules appear first on the lower surface and in highly susceptible cultivars the original pustules may be surrounded by colonies of secondary pustules.
- Pustules may also appear on the upper surface of the leaflet.
- They may be formed on all aerial plant parts apart from flower and pegs. Severely infected leaves turn necrotic and desiccate but are attached to the plant.
Management:
- Deep ploughing to bury surface litter, cultivation of groundnut in flat or lightly raised beds.
- Seed treatment with Trichoderma viride @ 4 g/kg seed and soil application of Trichoderma viride @2.5 kg/ha, mixed with 50 kg FYM or in conjunction with organic amendments such as castor cake or neem cake or mustard cake @ 500 kg/ ha.
- Seed treatment with 3 g Thiram + Carbendazim is recommended.
5.Groundnut Bud necrosis: Peanut bud necrosis virus (PBNV)
Symptom:
- Chlorotic spots appear on young leaflets and necrotic rings and streaks are developed.
- Terminal bud necrosis occurs when the temperature is relatively high.
- As the plant matures it becomes stunted with short internodes and proliferation of auxiliary shoots.
- The virus is mainly transmitted by thrips.
Management:
- Adopt a close spacing of 15 x 15 cm. Remove infected plants up to 6 weeks after sowing and spray Monocrotophos 36 WSC 500 ml/ha, 30 days after sowing either alone or in combination with antiviral principles. Antiviral principles from sorghum or coconut leaves.
- AVP are extracted as follows: Sorghum or coconut leaves collected, dried, cut into small bits and powdered to one kg of leaf powder two litres of water is added and heated to 60°C for one hour. It is then filtered through muslin cloth and diluted to 10 litres and sprayed. To cover one ha 500 litre of fluid will be required. Two sprays at 10 and 20 days after sowing will be needed.
6.Alternaria leaf disease: Alternaria arachidis and A. tenuissima
Symptom:
- Lesions produced by A. arachidis are brown in colour and irregular in shape surrounded by yellowish halos.
- Symptoms produced by A. tenuissima are characterized by blighting of apical portions of leaflets which turn light to dark brown colour.
- In the later stages of infection, blighted leaves curl inward and become brittle.
- Lesions produced by A. alternata are small, chlorotic, water soaked, that spread over the surface of the leaf.
- The lesions become necrotic and brown and are round to irregular in shape.
- Veins and veinlets adjacent to the lesions become necrotic. Lesions increase in area and their central portions become pale, rapidly dry out, and disintegrate.
- Affected leaves show chlorosis and in severe attacks become prematurely senescent.
- Lesions can coalesce, give the leaf a ragged and blighted appearance.
Management:
- Foliar application of Mancozeb (0.3%) or Copper oxychloride (0.3%) or Carbendazim(0.1%).
Source-
- TamilNadu Agritech Portal
