Infestation of this insect start appearing in the field, farmer has to take some immediate steps to save their crop from heavy yield loss from this insect.
Alterneria leaf blight: Alternaria macrospora
Symptoms
- The disease may occur in all stages but more severe when plants are 45-60 days old.
- Small, plate to brown, irregular or round spots, may appear on the leaves.
- Each spot has a central lesion surrounded by concentric rings.
- Several spots coalesce together to form blighted areas.
- The affected leaves become brittle and fall off.
- Sometimes stem lesions are also seen.
- In severe cases, the spots may appear on bracts and bolls.
Management
- Remove and destroy the infected plant residues.
- Spray Mancozeb or Copper oxychloride at 2kg/ha at the intimation of the disease.
Two to three sprays may be given at 15 days interval.
Red cotton bug:
Symptoms of damage:
- Infested seeds become discoloured and shriveled.
- Suck the sap from leaves and green bolls.
- Low germination and less oil content.
- Red stained lint and rooting bolls.
- Bacterium Nematospora gossypii enters the site of injury and stains the fiber
Identification of pest:
- Nymphs and Adults: Reddish bugs with white bands on the abdomen and black markings on the wings
Management:
- Conserve the biocontrol agent Harpactor costalis predaceous on nymph and adult
- Spray phosphamidon 40 SL @ 600 ml/ha
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