PRASANNA KUMARI, VJYOTHSNA, VULIMIRI2018-08-082018-08-082017http://krishikosh.egranth.ac.in/handle/1/5810063752D5447The present study on the characterization and management of Alternaria sesami on Sesamum indicum was taken up at the Agricultural College, Bapatla during 2016-2017. Alternaria leaf spot was mainly observed on the leaves in the form of minute brown spots that were round to irregular with concentric rings measuring up to one centimeter diameter. Disease prevalence and severity was less in young and vigorously growing plants, whereas in old and senescing plants it was more. Among Elamanchili and Nakkapalli mandals of Visakhapatnam district surveyed for Alternaria leaf spot occurrence, Elamanchili mandal was found with low disease severity that ranged from 9.57 to 15.62 % while in Nakkapalli mandal it varied between 22.07 and 60.80% with highest mean severity of 42.04 %. Alternaria sesami isolates when cultured on potato dextrose agar were mostly in hues of grayish brown colour with fluffy centre. Radial growth among isolates after seven days of incubation varied from 4.08 to 5.28 cm, while sporulation varied between 5.33 x 104 and 71.67 x 104 ml-1 . Conidial dimensions of 12 isolates varied from 24.88-34.64 X 9.61-12.13 µm with beak length of 5.12-8.32 µm. Number of horizontal and vertical septa varied from 2.76 to 3.82 and 1.31 to 1.76 respectively. EC of the halo primed solution was significantly high compared to other solutions used for priming (70.13 µS cm-1 ). An increase in EC was observed after hydro (from 0.02 to 0.20 µS cm-1 ) and bio priming (from 0.12 to 0.41 µS cm-1 ) for 24 h. Significantly high per cent germination was observed when hydro primed for 24 h (85.55 %) followed by hydro priming for 12 h (80.00 %) and 6 h hydro priming (73.33 %) and control (72.22 %). The highest per cent increase of 45.29 % over normal practice (mancozeb @ 0.25 % incubated for 6 h) was recorded when hydro primed for 24 h. There was no significant difference in mean germination time (MGT) of sesame seed in any of the treatments after 24 h of incubation. After two days of incubation, minimum MGT was observed in the six hour bio primed and 24 hour hydro primed treatment (3.03 days). Minimum MGT was in 6 h bio primed seed (9 days) while it was maximum in 24 h halo primed seed (9.53 days) after three days of incubation. Seedling vigour index was significantly high when hydro primed for 24 h (217.00) and least when bio primed for 12 h (62.54). Increase in seedling vigour index (108.77 %) was noticed over normal practice i.e., seed treatment with mancozeb @ 0.25 % for 6 h. In Alternaria leaf spot disease management, fungicidal treatment involving two sprays of propiconazole @ 0.1 % was found with significantly lowest PDI (53.89 %) with highest yield (463 kg ha-1 ). However, among the botanicals, neem leaf extract @ 5 % sprayed twice was effective in reducing the disease (PDI of 65.00 %) with an yield of 441 kg ha-1 next to propiconazole and chlorothalonil @ 0.2 % was on a par with chemical fungicide mancozeb @ 0.25 % sprayed twice. In yield economics, the highest net returns were registered in propiconazole treatment (Rs. 22,161 ha-1 ) that was followed by neem leaf extract treatment (Rs. 20,445 ha-1 ). Similarly, the highest benefit: cost ratio of 1.59 was obtained in propiconazole used treatment and was followed by neem leaf extract treatment (1.54).en-USnullThesis