Prioritizing components of package of integrated pest management in Indian mustard (Brassica juncea) in India for better economic benefit

Abstract Almost one-fourth of India's oilseed production is contributed by Brassicas. The Indian mustard [ Brassica juncea ] crop is affected by several biotic stresses in India, including aphid, white rust, Alternaria blight and Sclerotinia rot, which affect crop yields. Field trials were conducted at three locations during three crop seasons (2013–16) to evaluate treatments appropriate for mitigation of crop stresses and to obtain accurate assessments for seed yields and economic benefits as a part of a prioritized component-wise Integrated Pest Management strategy for the oilseed Brassica crop. The records from diverse sites and seasons concerning infestations by biotic stresses were assembled and scrutinized. The highest reduction in the severity of white rust disease was observed due to seed treatment by metalaxyl M 31.8 ES @ 6 ml/kg seed in one experiment and by a foliar spray of a combination of mancozeb 68% + metalaxyl 4% @ 1.7 g a.i./l in another trial, the latter being economically inferior to other fungitoxicants. The highest incremental benefit cost ratio (IBCR) was noted with the treatment of seed by an aqueous extract of garlic bulb (2% w/v) in one trial and by application of Trichoderma harzianum @ 1  g/l in another trial over sprays on crop foliage over two years and over three levels of nitrogen. Thiamethoxam 25 WG @ 1 g a.i./10 l ranked better than all other spray treatments in decreasing population of aphid in the top 10 cm main shoot at two sites. Pre-sowing application of T. harzianum @ 2.5 kg/ha soil provided better mustard seed yield in combination with spray with thiamethoxam 25 WG @ 1 g a.i./10 l on crop foliage and treatment of seed with T. harzianum @ 10 g/kg seed. Though the seed yield of mustard crop was the best with the integration of applications of T. harzianum on seed, to the soil along with spray of thiamethoxam 25 WG @ 1 g a.i./10 l on crop foliage at 50 days after sowing, it did not give the highest IBCR (16.6) among treatments. Contrastingly, treatment of seed with T. harzianum alone gave the highest IBCR (112.6), where the seed yield was relatively much lower (1469 kg/ha) whilst treatment of seed with fresh aqueous extract of garlic bulb @ 2% w/v also provided a high (80.4) IBCR. This paper highlights the impact of input costs, which allows growers to decide inputs based on the prevalence of biotic stress(es), the decision on intervention based on the importance of the same with an idea about the resultant quantifiable and monetary impact.