Abstract
Urdbean (Vigna mungo (L.) Hepper) is an important pulse crop grown worldwide. ULCV is an important disease of urdbean in Pakistan, because it causes huge losses in production of urdbean. The susceptible germplasm and favorable environmental conditions also contribute towards the wide spread outbreak of viral diseases. Forty urdbean lines were screened against ULCV under field conditions. Correlation studies between environmental factors (temperatures & relative humidity) and ULCV infection in selected lines revealed positive interaction for maximum and minimum temperatures but a negative one for relative humidity. The comparative efficacy of 2% concentration of different plant extracts (neem, akk, garlic) against ULCV was determined. Plants sprayed with neem extract have least whitefly population followed by garlic and results showed that minimum disease severity was observed on plants that were sprayed with neem followed by akk. The results are helpful in the understanding of epidemiological factors that play vital role in disease spread. Furthermore, the plant extracts can be used to manage the vector populations, which ultimately reduce the disease incidence. (C) 2011 Friends Science Publishers