Management of Alternaria Leaf Blight in Pigeonpea through Host Plant Resistance and Micronutrient Application

Abstract

Background: Pigeonpea [Cajanus cajan (L.) Millsp] is one of the primary grain legume crops grown in India for its high quality vegetable protein, animal feed and fodder. It is affected by various fungal and viral diseases. Among these, leaf blight caused by Alternaria alternata is one of the most destructive diseases and recently the disease of minor importance becomes major one in Tamil Nadu. Use of resistant cultivar is the most effective, economically viable and eco-friendly tool for combating the plant diseases. The micronutrients play a key role in many physiological and biochemical functions of the plants which influences plant pathogenic interaction. The micronutrients viz., Zn.Mn,Cu and Fe found to have greater impact on reducing the plant disease severity. Developing integrated disease management strategy involving disease resistant variety, micronutrient and fungicide application would be the best sustainable method for controlling the pigeonpea leaf blightMethods: Twenty four pigeonpea genotypes along with two local varieties viz., CO5 and CO6 were evaluated in the field for their resistance against Alternaria alternata leaf blight disease, consecutively for three years from 2015-16 to 2017-18 using the disease resistance scale ranging from 0 to 9. Field experiments were also conducted for three consecutive Kharif season from 2015 to 2018 to evaluate the efficacy of the foliar application of different micronutrients and combination fungicide viz., carbendazim 12% + mancozeb 63% on the incidence of leaf blight disease. Result: A total of 24 pigeonpea genotypes were screened for their resistance against leaf blight under field condition. Among these, four genotypes viz., BDN2, IPA 8F, IPA 15F and MA6 were found resistance and nine genotypes were moderately resistant and remaining 11 genotypes showed susceptible reaction to leaf blight. The results of the field experiment on micronutrient and fungicide application revealed that foliar spraying of MnSO 4 @0.2% on 30 days after sowing and carbendazim 12%+ mancozeb 63%@ 1g / lit on 45 days after sowing recorded the lowest leaf blight incidence of 8.1 PDI (Per cent Disease Index) with the highest disease reduction of 76.9% as against 35 PDI in the untreated control plot. The above treatments also recorded the highest grain yield of 905 kg/ ha as against 703 kg/ in the untreated control.