Early fruiting stage starts, irrigation should be given to the crop during this week. Farmer should check mealy bug infestation in the field.
Grey or Areolate mildew: Ramularia areola
Symptoms
- Irregular to angular pale translucent lesions on lower surface, bound by veinlets and grey powdery growth
- Light green specks on upper surface
- In severe cases whitish grey powdery growth on upper surface. Affected leaves dry up inward, turn yellow and fall prematurely
- Growing the resistant varieties like Sujatha and Varalakshmi.
Management
- Remove and burn the infected crop residues.
- Rogue out the self-sown cotton plants during summer months.
- Avoid excessive application of nitrogenous fertilizers/manures.
- Adopt the correct spacing based on soil conditions and varieties.
Spray the crop with Carbendazim at 250-375g or wettable sulphur at 1.25-2.0 kg/ha, repeat after a week.
Mealy bug
Description of Insect Stages
The female mealy bug is oval shaped, 3-4 mm in size, wingless and covered with white hydrophobic (water repellent) mealy wax. There are dark bare spots on the thorax and abdomen, which appear as dark longitudinal lines. Mature females are often found with waxy pouches called ovisacs containing eggs. The adult male is about 1 mm long, with a grey body and a single pair of transparent wings. Two filaments of white wax project from the end of its abdomen. The adult male has no feeding mouthparts and causes no damage.
Symptom of damage
- Heavy clustering of mealy bugs usually seen under surface of leaves as a thick mat with waxy secretion
- Excrete copious amount of honey dew on which the fungus sooty mould grow
- Affected plants appear sick and black, resulting reduced fruiting capacity
Management
- Remove the alternate weeds hosts
- Monitor the incidence regularly and look for crawler emergence
- Take up the management at intial stage to get maximum control
- Wherever necessary use neem based botanical insecticides such as neem oil 2% or NSKE 5% orfish oil rosin soap 25g/litre of water.
- Use of Encyrtid parasitoids, Acerophagus papayae @ 100 per village against Paracoccus marginatus and Aenasius bambawaeli against Phenococcus solenopsis are recommended
- Use of dimethoate or profenophos 2 ml/lit may be adopted as an alternative.
Tobacco Streak Virus
Symptoms
- The acute or necrotic stage – local lesions appear as rings, irregular purplish spots or solid necrotic spots.
- The early recovery stage – new leaves develop which appear normal except for chlorotic veins
- The chronic or late recovery stage – the leaf is thicker than normal with a smoother texture and the tubular corolla splits with the petals becoming separated an/d square are drying.
Management
- Spray Acephate 450 g / acre.
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