FOR cotton farmers in Sindh, pink bollworm has become a real threat. The pest not only reduces yield, it also damages the lint quality by causing yellow spots on the fibre, which lowers its cost in the international market.
The insect completes four generations on cotton crop and the larvae of the fifth generation lives in the leftover bolls after final picking in diapausing stage. Resultantly, the infested bolls do not open and stay on cotton sticks. Since a majority of cotton growers are not aware of this, they keep waiting for the remaining infested bolls to open which delays the sowing of wheat crop, particularly in case of the late sown cotton.
Historically, Sindh’s cotton crop did not suffer from pink bollworm until 1980. But due to absence of Domestic Plant Quarantine Regulatory Service in the country, the pest entered the province with Niab-78 variety of cotton. Since this variety of Punjab was high yielding and early in maturing, its massive inflow in Sindh could not be checked. Within a short span of time Niab-78 and other cotton varieties of Punjab replaced the varieties of Sindh. However, the appearance of pink bollworm remained sporadic and negligible in lower province and almost nonexistent in the upper Sindh cotton belt. The main reason was probably the prevailing climatic condition of the province.
In 2002, however, a new development took place in the arena of cotton crop in Sindh: the introduction of illegal Bt cotton. In lower Sindh, the variety was known as Australian Bt while in upper Sindh it was Bt 121. Both the varieties were found to resist American, spotted, and pink bollworms, requiring just two to three sprays for sucking pests, and growers accepted them warmly. Very soon, a majority of the cotton area in the province came under Bt cotton.
With the passage of time many Bt cotton varieties, developed locally by research institute and local seed companies, came in the market under different names. Unfortunately, no government body, either at the federal or provincial level, is active in the field to check whether cotton seeds available in the market are authentic or not. According to media reports, four research institutes have concluded that none of the 71 Bt cotton varieties they tested contained the required level of toxin needed to kill two types of pests — army worm and bollworm.
The situation in Sindh is worse than in Punjab because a majority of cotton growers, big or small, buy seeds from cotton ginning factories and agribusiness dealers on defer payments on high mark up (20-30 per cent for six months).Since beggars can’t be choosers, the growers accept what is offered. This is why particularly in upper Sindh 3-4 types of Bt cotton varieties are found at a time in the same cotton field. And this mixing of seed is proving disastrous for the cotton growers.
The field staff of the provincial agricultural department has confirmed pink bollworm in cotton fields in Mirpurkhas, Sanghar, Hyderabad and Nawabshah and Badin districts. The intensity of the pink bollworm attack in Sanghar district could be gauged from the fact that many ginning factories of Salehpat and Rohri Talukas of district Sukkur have stopped buying phutti from Sanghar district because of high percentage of yellow cotton following the infestation.
The situation in upper Sindh is disturbing as well. Survey of cotton crop in prime cotton belt of districts Sukkur and Khairpur (Nara cotton belt), undertaken by this scribe in late September 2013, revealed a widespread insurgence. The survey also indicated a lot of standing Bt cotton crop, whether sown early or late, harbour pink bollworm in flowers, squares and bolls. Flower infestation recorded was from 1-6 per cent whereas boll infestation was 4-30 per cent in the bolls meant for second picking.
Since the present situation has been caused mainly due to non-availability of good quality cotton seed, it is essential that national food security, research ministry and the agricultural department of the Government of Sindh takes appropriate measures on war footing so that the next cotton crop in the province can be saved from bollworms.
The main source of carryover of pink bollworm from one season to another is the diapausing larvae which live inside the leftover bolls after final picking. Therefore, the provincial agricultural department should launch a campaign advising cotton growers to destroy the cotton bolls through animal grazing and trash burning. The burning of discarded cotton seeds in the ginning factory should also be made mandatory.
Chemical control of pink bollworm is difficult because the larvae spend most of the time within the fruiting bodies. For proper control 4-5 sprays with highly toxic pesticides is required at weekly intervals. However, since frequent use of highly toxic pesticide can convert cotton fields into a biological desert and result in outbreak of spider mites, army worms and American bollworms, the best control would be the use of pheromone as has been earlier demonstrated. Moreover, controlling pink bollworm with pheromone is environmentally safe.
The writer is ex-entomologist, Federal Plant Protection Department