The target for wheat, which is grown on about 8 million hectares, is fixed at 8.41 million hectares and the production at 20 million tons. Rain in Punjab has improved the crop prospects with indications of achieving the target.

Federal Minister for Food and Agriculture, Khair Muhammad Jonejo, has also expressed his optimisms about the size of the crop despite 60 per cent water shortage in the canal irrigated areas.

However, in upper Sindh region, particularly in districts Khairpur, Sukkur, Ghotki, Larkana, Shikarpur and Jacobabad, on account of water shortage harvesting of rice crop was delayed and cotton picking too, started late due to which wheat sowing continued up to the second week of January.

As a result vast acreage of the standing wheat crop are still in its booting to milky stage of growth. It is commonly recognized that there are certain restricted time limits for sowing of crop for best results defined by the temperature of the locality.

When sowing is delayed the length of the development period accordingly, decreases. Therefore, one day delay in sowing of wheat after 20th November results in reduction of grain yield by 10-12kg per acre. Besides, it is a proven fact that the shortening of development stages under the influence of high temperature, particularly in March and April, is usually followed by lowering in the yield.

This year due to late sowing 80 to 90kg seeds and 3 to 4 bags of fertilizer per acre have been applied against the recommended 60kg of seeds and 2 to 3 bags of fertilizer. The survey of wheat crop in district Khairpur and Sukkur has indicated that the standing wheat crop sown after mid-December up to first fortnight of January has come under low to severe aphid attack.

However, the worst affected are those sown as inter-cropping under date palm or mango orchards. Besides, wheat fields having more number of shady trees on field bunds also harbour aphids infestation.

The intensity of the attack could be gauged from the fact the number of aphids range from 80 to 120 per earhead, besides, 10 to 20 on leaves and stems of the plant.

Similarly, late sown wheat crop still in its pre-booting to booting stage harbour 2 to 15 aphids per plant. It would be proper to mention here that like other winter aphids, the wheat aphid breeds at fast rate during cold weather and reaches the height of its population in February-March when the ears start ripening.

The insects are green, inert louse like. They suck sap from the ears and tender leaves and decrease the yield. The damage is particularly severe in years of cold and cloudy weather. Since well-manured succulent crop harbour the pest for longer period it is apprehended that the late-sown crop may badly be damaged if the present cool and time to time cloudy weather continues till the end of March.

Natural control: Natural enemies of aphids play a big role in reducing their numbers. Probably the greatest and the most abundant predator of aphids is the ladybird beetles. It has been estimated that one ladybird beetle can consume up to 200 aphids in one day. Both, adults and larvae of the ladybird beetle are ferocious predator of aphid. Besides, ladybird beetle chrysopa, orius and other predatory insects are also important natural controlling agent of the aphids.

Chemical control: Following no advice from the provincial agriculture extension department regarding the measures for handling aphid insurgence on wheat crop many growers following the advice of pesticide dealers have started spraying wheat crop with methamedophos. Although, this pesticide is not recommended for wheat aphid because of its high toxicity, but it is used by the growers as it is cheep.

Suggestions: Since wheat crop is the only major cereal grain crop in Pakistan which is almost a pesticide-free crop hitherto, it is warranted that the wheat research institute Sakrand, as well as wheat research wing of the NARC Islamabad should apprise the growers about the economic injury of aphid so that injudicious use of pesticide for aphid control could be discouraged. This is necessary as injudicious use of pesticides may prove disastrous in the long run.