Management of Insect Pests of Sorghum
Sorghum is one of the most important cereals in the semi-arid tropics. Avoidable losses have been estimated to be over 32% in India due to various insect pests. Various insect pests are borers (shootfly, stem borer), earhead borers (earhead caterpillar, shoot bug, ear head bug),and sap feeders (sorghum midge). Major insect pests and their management is described...
1. Shootfly: Atherigona varia soccata
This is the major pest in the early stage of the crop. The maggot bores inside the stem and cuts the growing point. Central shoots dries and produce "dead heart" symptom. The infested plant produces side tillers. The management is done at ETL: 1 egg/plant in 10% of plants in the first two weeks of sowing or 10% dead hearts. Seed treatment with imidacloprid 70 WS @ 10 g/kg of seeds and thinning of the nursery.
2. Stem borer, Chilo partellus
This pest causes damage as three levels i.e, causes leaf damage, dead heart and at the time of harvest it lead to stem tunneling. Withering and drying of central shoot -"dead heart". Red mining in the midrib. Bore holes visible on the stem near the nodes. Tender folded leaves have parallel "shot hole". Affected parts of stem may show internally tunneling of caterpillars. Management to be taken when ,ETL: 10% damage. Sowing the lab lab / cowpea as an intercrop to minimize stem borer damage (Sorghum: Lab lab /cowpea 4:1). Set up of light traps till mid night to monitor, attract and kill adults of stem borer.
3. Ear Head caterpillar : Helicoverpa armigera
Ear heads are partially eaten with chalky appearance. Fecal pellets are visible within the ear heads. Manage when ETL: 2 / ear head. Set up of light traps till mid night to monitor, attract and kill adults of stem borer, grain midge and ear head caterpillars. Set up sex pheromone traps at 12/ha to attract male moths of Helicoverpa armigera from flowering to grain hardening.
4. Shoot bug: Peregrinus maidis
Plants become unhealthy stunted and yellow. The leaves wither from top downwards. Panicle formation is inhibited and the plants die if attack is severe. Honeydew secreted by the bug causes growth of sooty mould on leaves. The midribs of the leaves turn red due to egg-laying and may dry up subsequently. Spray with 0.04% diazine (or) dimethoate 0.02%. Application of phosphomidon @ 250 ml in 450-500 litres water/ha.
5. Earhead bug: Calocoris angustatus
Nymphs and adult suck the juice from within the grains when they are in the milky stage. Grains shrink and turn black in colour and ill filled (or) chaffy. Presence of large number of nymphs and adults are seen on the ear head. Manage when ETL: 10 / ear head. Apply any one of the following on 3rd and 18th day after panicle emergence : Carbaryl 10 D 25 kg/ha, Malathion 5 D 25 kg/ha .Neem seed kernel extract 5%.
6. Sorghum midge: Contarinia sorghicola
Pollen shedding due to egg laying. White pupal cases protruding out from the grains . Chaffy grains with holes. Set up of light traps till mid night to monitor, attract and kill adults of stem borer, grain midge and ear head caterpillars. Apply any one of the following on 3rd and 18th day after panicle emergence : Neem seed kernel extract 5% (or) Spray malathion 50 EC @ 1600 ml/ha or phosalone 1150 ml/ha. The sowing of sorghum should be completed in as short a time as possible to avoid continuous flowering which favours grain
midge and ear head bug multiplication in an area.
About Author / Additional Info:
I am Ph.D. research scholar in the Department of Entomology at JNKVV, Jabalpur.