Epidemiological Characterization of Turnip Leaf Spot Disease and its Management

Abstract

Turnip crop is badly affected by Alternaria leaf spot (ALS) that cause huge qualitative and quantitative losses. The objectives of present study were to evaluate the resistance of turnip germplasm against ALS, effect of environmental variables on ALS disease development, management of ALS disease through nutrients and to compare the yield parameters of both healthy and infected turnip plants. Turnip germplasm consisting of 4 varieties (Nankana Red, Golden Ball, PTWG and Purple Red) were sown for screening against ALS under natural conditions using augmented design. Similar varieties were sown for the management of ALS through nutrients which were applied weekly and data of disease severity was recorded after each application. The data of environmental variables were obtained from weather observatory and subjected to correlation analysis to check its effect on disease development. Yield parameters i.e. plant height, shoot length, root length, fresh and dry weight were recorded from both healthy and diseased plants. None of the 4 varieties were found to be immune or highly resistant according to disease rating scale. Nankana Red and Purple Red were resistant and highly susceptible against ALS disease, respectively. There was significant reduction of yield parameters in diseased plants which was boosted after the application of treatments. The combination of 4 treatments (sulphates of manganese, zinc, copper and boric acid) gave the highest yield reduction with 18.45% disease severity. The effect of temperature and wind speed was positive while of relative humidity and rainfall was negative with ALS disease development. This research provides valuable insights into the management of leaf spot disease and highlights the need for sustainable agricultural practices to ensure food security.