Effect of Soil Moisture and Temperature on Population Dynamics of Fusarium udum Causing Pigeonpea Wilt

Fusarium wilt is an important soil borne disease of pigeonpea [Cajanus cajan (L.) Millsp]. Highest population density of Fusarium udum 236.30 cfu/g of soil was recorded at soil depth of 0–10 cm, followed by 191.00 cfu/g of soil at 11–20 cm soil depth. Decrease of pathogen population was recorded in samples drawn from the deeper layers of soil. Incubation of F. udum infested soil samples from one to ten months indicated that, incubation of soil samples at temperature range 25 to 30°C at 75% water holding capacity was favourable for growth and multiplication of F. udum (196.00 cfu/g of soil). Whereas, least population density was recorded in soil samples incubated at 45°C temperature at 25 to 50% water holding capacity. It was also noticed that population density decreased with increase in incubation periods.