Incidence of insect-pests in response to plant density and nutrient levels in Desi cotton (Gossypium arboreum) under rainfed condition

Abstract

The field experiment was conducted to study the effect of spacing and nutrients on insect-pests infestation on compact desi cotton (Gossypium arboreum) grown under rainfed condition during kharif seasons of 2019–20 to 2021–22 at the Main Cotton Research Station, Navsari Agricultural University, Surat. The experiments were carried out in factorial randomized block design with nine treatment combinations with three replicates comprised of three levels of spacing viz., 60 cm × 15 cm, 60 cm × 30 cm and 120 cm × 45 cm and three nutrient levels, viz. 120, 150 and 180 kg N/ha. The population of sucking pests viz., leafhopper, thrips, whitefly and mealy bug as well as open boll and locule damage by bollworms was recorded significantly lower in plant density at normal (recommended) spacing, 120 cm × 45 cm and vice a versa. Only the aphid population was found significantly lowest in closer spacing (60 cm × 15 cm). Amongst nitrogen levels, there was a significant difference with respect to N levels and the highest population of sucking pests as well as open and locule damage was recorded at N level of 180 kg N/ha. With respect to treatment combinations, there was no significant difference in sucking pests (aphids, thrips, whitefly and mealybugs) and open boll and locule damage amongst different treatment combinations of spacing and nitrogen levels. However, the treatment combination comprising the spacing of 120 × 45 cm and 120 kg N/ha recorded significantly lowest population of leafhopper followed by treatment combination of spacing 120 cm × 45 cm with nitrogen level of 150 kg/ha. Hence, proper interventions for leafhopper control is required when compact desi cotton was sown at closer spacing under rainfed condition.