Studies on Effect of Epidemiological Factors on Alternaria Leaf Blight of Turmeric

Abstract

Although turmeric is considered to be a medicinal plant, it is susceptible to various diseases. Among the various diseases, leaf blight caused by Alternaria alternata (Fr.) Keissler, is one of the most serious foliar disease. The investigation on effect of epidemiological factors on leaf blight disease of turmeric was conducted during Kharif 2018 and 2019 at Krishi Vigyan Kendra, Kalaburagi, University of Agricultural Sciences (UAS), Raichur. The progress of leaf blight disease in turmeric variety Salem, sown at two different dates at an interval of 15 days gap in sowing i.e., 28th May and 11th June was made. The disease progress was recorded at a weekly interval and correlated with corresponding weekly weather factors. During Kharif 2018, initial symptoms of leaf blight disease were appeared on 33rd standard meteorological week (SMW) with the record of 5.34 PDI and the disease progressed and reached the maximum intensity of 66.10 PDI by 49th SMW (3rd fortnight of January 2019). Similar trend in disease progress was observed in second date of sowing (11th June), where in initial symptoms of leaf blight were noticed during 34th SMW with initial infection of 2.30 PDI. Further, the disease continued to progress and reached its high intensity of 70.26 PDI by 2nd SMW i.e., second week of January, 2019.  During Kharif 2019, the first date of sowing (last fortnight of May) recorded initial disease intensity by 32nd standard meteorological week (6th August, 2019) with 3.0 PDI. Then the disease raised up to the maximum intensity of 57.88 PDI by 48th SMW (November last fortnight). In the second sown crop, the maximum disease intensity of 67.83 PDI was recorded during December first fortnight of 49th SMW. However, the disease was initiated with an initial infection of 0.75 PDI during 34th SMW and went on progressing and reached the peak intensity.