COTTON is highly weather sensitive crop. Favourable weather condition at the time of sowing that gave good germination, no incidence of pest attack, increase in the number of bolls and weight, low weed intensity, favourable difference between day and night temperatures enabled the country to harvest a record crop of 14.618 million bales in 2004-05.

The per hectare average cotton yield in Pakistan is around 595 kg, which is much lower than that of China’s 1,109 kg, USA’s 917 kg and the world average of 709kg. An attack of insects, pests and diseases at different crop growth stages as well as failure of the growers to effectively control these biotic agents because of adulterated pesticides, faulty spraying equipments and ill-trained spraying labour, contribute to low per hectare yield.

The ministry of food, agriculture and livestock (Minfal) has set a target of cotton output at 15 million bales for 05-06 encouraged by the last year’s performance. But this year, the weather has turned hot and humid that is favourable for the spread of pest and disease. Wide differences between day and night temperatures and threatening floods this year may make it difficult to realize the target.

As rains and humidity create an environment for pest attack, the farmers have to use insecticides and pesticides at an early stage. About 90 per cent pesticides are sprayed on cotton crop. Recently, the government’s decision to slap five per cent duty on solvents used in manufacturing of different pesticides would increase prices and hurt the farmers.

Cotton is a major non-food cash crop and accounts for 10.5 per cent of the value-added in agriculture and about 2.4 per cent to gross domestic product. It provides raw material to local textile industry that is the largest segment of industry.

Weeds are injurious to the growth and development of cotton plants because weeds share resources including nutrients, moisture, light and space with crop plants. Some important weeds in the cotton field include field bindweed, Bermuda grass, crab grass, datura, blue grass, it sit, and khybal grass etc.

As cotton plants grow slowly early in the season, so they are less competitive with weeds. In the backdrop of recent rains, weed density would be higher in the cotton fields. To eradicate the weeds, the growers should spray weedicides at an early stage of growth but it would increase the cost of production.

As the weather has turned hot and humid due to heavy rains, there are more chances of insect/pest attack at an early growth stage. Cotton is very sensitive to insect/pest attack. A number of insects and pests right from seedling to fruiting stage attack cotton crop inflicting 20-30 per cent damage. White fly, jassids, aphids and armyworm etc are important sucking insects/pests. American, pink and spotted, are the bollworms that inflict serious damage to cotton crop at later stages.

A bumper cotton crop may be harvested in one year but in the very next year, the output may slump to low levels because of cotton leaf curl virus transmitted by white fly. The white fly becomes the most important pest. Being a sucking insect, its feeding removes nutrients from the plant that result in stunting, poor growth, defoliation, boll shed and reduced yields. Thanks to introduction of virus resistant varieties, the problem of leaf curl virus has been averted to a greater extent.

Cotton aphid is highly variable in body size and colour and sucks the plant juice and impairs the quality of the produce as well. Armyworms suck juice and create holes in the leaves that fail to carry out photosynthesis. Cotton boll worms larvae damage bolls and squares. Squares injured by cotton bollworm usually have a round hole near the base. Spotted bollworm generally attack six-week-old crop. It bores into the shoot and boll and causes drooping and drying of the shoot.

American bollworm is the most destructive pest of cotton and feeds in the internal content of the boll by thrusting its head inside. Damaged bolls drop from the plant. In Pakistan, American bollworm is the most damaging pest of cotton after leaf curl virus was brought under control. Pink bollworm feeds on the seeds and moves to the adjacent boll by boring a hole. Infested flower buds shed prematurely.

In short, insects and pests cause damage to leaves, branches, flowers, squares, bolls and lint in varying degree. In order to control weeds, pre-plant tillage, crop rotation, and the use of herbicides are effective measures. Integrated weed management approach is the most effective technique against weeds.

Insects/pests can best be controlled through the integrated pest management (IMP) approach that requires a variety of measures like deep ploughing exposing insect stages to desiccate predators as well as destroy the crop residues to prevent carryover of the pest to the next season; growing certified acid delinted seeds of cotton varieties resistant to bollworms; avoiding continuous cropping of cotton in the same area; judicious water management for the crop to prevent excessive vegetative growth and larval harbourage; hand picking and destruction of affected plant parts; installing pheromone traps on cotton heaps to trap male moths of pink bollworm; destroying left over bolls, which contain pink bollworms, using trichograma cards in cotton fields to destroy eggs of American bollworms; applying IGRs at early stage of the crop to contain armyworm; applying timely and balanced fertilizers to prevent breakout of virus infection and attack of insects/pests before August 15; controlling sale of fake and spurious pesticides in the market and ensuring efficacious; effective and quality pesticides to farmers at affordable prices and maintaining recommended plant density per field.