Off-Season Management Of Pink Bollworm 

By Amandeep Kaur 

and Vijay Kumar

Cotton is the second most important Kharif crop grown in the Southwestern districts of Punjab namely Fazilka, Mansa, Sri Muktsar Sahib, Sangrur, Bathinda, and Faridkot. For the last 5-6 years, the incidence of pink bollworm is being recorded on Bt cotton hybrids in Central and Southern India and now it has become a major pest of Bt cotton. During 2021, almost all major districts of the cotton belt reported the incidence of pink bollworm where incidence ranged from 0 to 90 percent. As we know pink bollworms survive only on cotton under North Indian conditions and we can easily curtail the life cycle of the pest. During the crop season (April to November), pink bollworm completes its life cycle in 30-35 days and has 4-5 generations in a year. However, during the winter season (December-March), its larvae undergo diapauses in the half-opened cotton bolls attached to the uprooted cotton sticks and in the harvested seed cotton and have a longer life span of 60-75 days as larvae. 

Carryover of Pink bollworm: Carryover of this pest during winter is the most important weak link which should be targeted for its management. The old stack of the previous year's crop carrying unopened or half-opened bolls infested with pink bollworms plays a major role in the next year or the coming year's field infestation. All the seed-cotton in the ginneries, ginning waste, all trash collected during the ginning process, seed left uncrushed in the mills, and non-fumigated seed retained or sold by the ginneries are the major source of survival of pink bollworm during the off-season. The larvae in the bolls pupate and adults emerge out and cause a new infestation in the nearby cotton fields. Thus, various off-season and seasonal management strategies developed by PAU are discussed below:

Integrated Pest Management

Being monophagous in nature, pink bollworms feed only on cotton so it’s easy to manage this pest by breaking its food cycle. The following integrated pest management strategy should be adopted for its effective management.

Cultural and mechanical control

• Movement of the cotton sticks carrying unopened or half-opened bolls from the infested areas to the new areas should be strictly avoided.
• After the final picking, PBW Infested cotton fields should be shredded with the help shredder to kill the larvae.
• After the last picking, allow sheep, goats, and other farm animals into cotton fields to feed on plant debris and unopened bolls.
• Do not stalk the cotton sticks under shade or in the field. Beet the sticks on the ground to dislodge the pink bollworm larvae surviving the unopened bolls. 
• Stalk the cotton stick vertically away from the fields.
• Consume/ destroy the sticks by mid-March.
• If possible, cover the stored sticks with a mosquito net (fine net) so that emerging adults do not come out.

Prevention of spread from cotton ginning mills

• Cotton in the ginning mills should be covered with polythene sheets
• Seed-cotton movement from the pink bollworm-infested areas should be prevented to the cotton ginneries operating in non-pink bollworm infestation areas.
• All the seed cotton in the ginneries should be ginned by the end of March and ginning waste must be destroyed immediately.
• Destroy all trash collected during the ginning process. 
• Fumigate the seed left uncrushed in the mills before the end of April with Celphos/Phostoxin/Delicia @ one 3-g tablet per cubic meter space, giving an exposure of 48 hours, or use two tablets with an exposure of 24 hours. 
• Non-fumigated seeds should not be retained or sold by the ginneries. 
• Only cotton-seed cake (Khal) should be fed to the cattle and no seed should be kept for this purpose.
• The seed meant for sowing must be acid-delinted/fumigated in the ginneries before it is sold. The acid treatment kills the larvae of the pink bollworm. It also removes fuzz and thereby facilitates mechanical sowing. 
• Even the apparently healthy seed cotton (kapas) may be harboring larvae of pink bollworm. Hence, kapas retained by the farmers should be ginned by the end of March and seed fed to cattle or covered it 
• The pheromone traps should be installed near the cotton ginnery for early detection of the pest.

Farmers should remain vigilant and contact Krishi Vigyan Kendras or Farm Advisory Service Centre or Regional Research Station of PAU or the Department of Agriculture and Farmers’ Welfare, Punjab if any incidence of pink bollworm on Bt cotton is observed.

*Authors are from the Department of Entomology, PAU, Ludhiana