Environmental factors affecting disease development and viability of smut of pearl millet pathogen in soil
2012
and ASHA SHIVPURI, R.L. MEENA*, A.C. MATHUR
During the five consecutive cropping seasons smut severity and weekly meteorological data on temperature, relative humidity, rainfall, sunshine and wind velocity were recorded from boot leaf stage to till the formation of grains to find out their correlation with smut severity. Maximum temperature (33.2 to 34.9oC) and minimum (23.7 to 24.9oC) temperature have negative correlation with disease severity, while maximum (70.3 to 79.5%) and minimum (43.0 to 56.7%) relative humidity in the month of July-August have positive correlation with disease severity. Similarly rainfall has highly significant positive correlation with smut severity. Sunshine hours have negative effect on smut that decreased with the increase in sunshine (hours/day). The variables minimum temperature and maximum relative humidity had negative partial regression coefficients in multiple regressions. Teliospores of smut fungus perpetuate in soil as inoculum source for next crop. The teliospores were buried in nylon bags at different depths of 0,5,10,15,20,25 and 30 cm in cage house soil. Samples were taken out at three months interval up to 30 months to know the viability at different depths. Of the seven burial depths average minimum (1.0%) and maximum (4.6%) germination of teliospores was observed at 30cm and 10cm soil depths respectively even after 30 months of burial. The germination of teliospores was declined sharply (83.9 to 2.5%) as duration of burial increased. This indicates that deep ploughing of the infested fields may be a useful practice to reduce the inoculums.
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