Department of Plant Pathology, CSK HPKV, Palampur-176062.
Abstracts of Research Papers Presented during the National Symposium of Indian Virological Society at Unit of Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi-110 012, October 14–1.
Epidemiological studies were conducted on leaf crinkle disease of urdbean (Vigna mungo L. Hepper), caused by a filamentous flexuous seed borne virus using infected and healthy seeds of two recommended varieties (T 9 and PDU 1) under protected and unprotected natural epiphytotic conditions. Two years field trials revealed that infected seed played an important role in the initiation, establishment and spread of the epidemic. The disease incidence in protected crop remained static in both the varieties after expression of seed borne infection, whereas in unprotected crop, the disease incidence reached up-to 25.29 - 38.37% in T 9 and 13.39 - 14.57% starting from 2.33% and 1.34%, respectively, thereby indicating the role of vectors in the spread of disease. The temperature and relative humidity ranged between 18–29°C and 52–88.8 per cent, which were optimum for vector activity and disease development. The partial correlation coefficients of weather variables were positively correlated with disese. Multiple correlations of coefficients between disease incidence and independent variables were 93.77% and 96.55% in protected crop and 98.28 and 99.52% in unprotected crop of cv. T9 and PDU 1, thereby indicating that the variables taken into account during the course of studies contributed up-to 99%. The vector populaiton had positive correlation with disease though not significant, further significying the role of vector in the spread of the disease.
