Effect of environmental factors and inoculum age on fenugreek infection by Peronospora trigonella causing downy mildew

Study of different environmental factors on fenugreek infection by Peronospora trigonella revealed that, plants incubated at 18°C temperature showed highest (50.27%) disease intensity, disease decreased with increase in temperature. Different light regimes affected conidial germination. Maximum (63.49%) disease intensity was observed in complete darkness. Minimum (24.72) per cent disease intensity was observed in complete light condition and all light treatments significantly influenced disease severity. Maximum PDI was observed when 12 hours old inoculum was used and was at par with 24 hours old inoculum. Age of host also affected the infection; 45 and 60 days old plants were most susceptible to downy mildew. Studies on leaf wetness, showed that maximum (57.37) PDI was observed when leaves were kept wet for 12 hours followed by leaves kept wet for 16 hours, showing 53.57 per cent disease intensity.