Management of insect pests of wheat
Authors: Vikas Gupta, Satish Kumar and Chandra Nath Mishra
Indian Institute of Wheat and Barley Research, Karnal-132001 Haryana
Every year on an average 20 - 25% of wheat is lost due to insect pests and diseases. The situation is further aggravated on storage. The termites, aphids, armyworm, American pod borer and brown mite are the major pests of wheat. Major insect pests and their management is described.
i) Termites or white ants:
Termites that were previously known to be serious pests of rainfed crop are now a day commonly infesting irrigated crop also. Since it is a polyphagus pest we cannot screen germplasm against this pest for identification resistant sources. Thus seed treatments and broadcasting of different insecticides are recommended for its control. Seed treatment @ 4ml of Dursban/Durmet 20EC per kg of seed is suitable for controlling termites.
Wheat aphids pose a serious threat to wheat cultivation in northern India. These are soft bodied, green to blackish green louse like insects found in small colonies on leaves and spikes. Aphids can cause 3-21 % loss in wheat yield when appear beyond economic threshold levels. In case of high population, chemical control is practiced. Regular screening of germplasm against this pest has put up no resistant source. Thus control of this pest is generally done with chemicals. Spray the crop with 150ml of Rogor 30EC in 80-100 litres of water per acre.
The pest is destructive in the larval stage only. The newly hatched larvae feed on tender leaves. The grown up larvae feed on leaves, flag leaf, awns, glumes and on the developing grains. At higher populations it defoliates the plants completely and feeds on the grains in the milky stages. Under such situations it causes yield losses upto 40 per cent. Late sown, high yielding heavily fertilized and well irrigated crop suffers more losses due to attack of armyworm. Since it is a polyphagus pest, it is difficult to screen germplasm against this pest for identification resistant sources. Thus chemical control with insecticides is recommended. Spray 200 ml of dichlorvos 85SL in 80-100 litres of water per acre.
iv) American pod borers:
This is a sporadic pest of wheat and does not infest the crop every year. The incidence is high in fields where wheat follows cotton. It generally appears in the month of March-April. One can identify this pest by the presence of whitish faecal pallets on the ground. This pest also being polyphagus is controlled chemically. Spray 800ml of quinalphos 25EC in 100 litres of water per acre using knapsack sprayer.
v) Pink stem borer:
This is newly emerging pest. This pest is mainly observed in fields where rice-wheat cropping pattern is practiced. It generally attacks the wheat crop at seedling stage. The larva bores the stem of young plants and kills the central shoot causing 'dead heart'. The infested tillers first look pale brown and ultimately dries up. At the ear emergence due to its attack 'white ears' are produced which have little or chaffy grains. This pest is also chemically controlled. Spray 800ml of quinalphos 25EC in 100 litres of water per acre using knapsack sprayer.
vi) Brown wheat mite:
The brown wheat mite is cosmopolitan pest of wheat causing discoloration of leaves. It is more serious on unirrigated than the irrigated crop. This pest can be controlled by spraying the crop with 40ml of imidacloprid 200SL or 12g of clothianidin 50WDG or 150ml of Rogor 30EC in 80-100 litres of water per acre using knapsack sprayer.
About Author / Additional Info:
I am working as a Scientist in Indian Institute of Wheat and Barley Karnal, Haryana under ICAR, New Delhi.