Tobacco Stem Borer

📖 Description

Tobacco Stem Borer (Phthorimaea heliopa) is an important pest of tobacco across the Indian subcontinent, particularly severe in tobacco belts of Andhra Pradesh (Guntur, Prakasam, Krishna), Gujarat (Vadodara, Anand), Karnataka (Mysore, Hassan), Telangana and West Bengal where tobacco is grown on over 300,000 hectares. The larva bores into tobacco stems, causing characteristic swelling and deformation at the bore site, yellowing and wilting of leaves above the bore point, and ‘dead heart’ symptom in young plants (central shoot dies). The pest is particularly damaging in nurseries and young crops (first 4-6 weeks after transplanting) where infestation can stunt or kill plants. Outbreaks are favoured by warm dry weather and continuous tobacco cropping. The pest is difficult to control because (a) larvae are protected inside stems where contact insecticides don’t reach, (b) damage is often not detected until plants begin to wilt, and (c) timing of insecticide application is critical — must be done at early stage before larvae bore into stems. IPM with pheromone trapping of males, Bt applications against young larvae before boring, hand-collection and destruction of infested stems, crop rotation with non-host cereals, and deep summer ploughing provides effective control. The pest is most severe in nurseries and young crops — protecting the nursery with Bt applications and using clean nursery stock for transplanting are key preventive measures. Quarantine of nursery stock is critical — most new infestations originate from infested transplants.