*Deptt. of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana-141004
Punjab Agricultural University, Regional Station, Faridkot
National Symposium on “Plant Pathology in the Changing Global Scenario” held at National Bureau of Plant Genetic Resources, New Delhi on February 27–28, 2009
The disease caused by gemini virus, transmitted by whitefly was first noticed in Nigeria on Gossypium peruvianum and G. vitifolia. Till now, the disease is known to be caused by DNAA/DNA-1/DNA beta complex. Depending upon the infection and stage of the crop, this malady not only reduces seed cotton yield but also adversely affect the quality of the fiber. Considering the importance of the malady, the present investigations were undertaken with the objective to work out the relationship of weather parameters (temperature, relative humidity and rainfall) with the incidence of CLCuD in a cropping season. For this purpose, the experiment was conducted in Kharif 2006 and 2007 at Punjab Agricultural University, Regional Station, Faridkot with leaf curl susceptible varieties viz., F 846 and RS 921. The crop was sown with row to row spacing of 67.5 cm and plant to plant spacing 30.0 cm in a plot of 270 m2. All the recommended packages of practices were followed. Observations on the appearance and progress of CLCuD incidence (from each plant), along with whitefly population per three fully developed leaves from 20 randomly selected plants were taken at weekly intervals starting with the onset of disease. The data were taken till the occurrence of maximum disease incidence, for each year. The daily data regarding maximum and minimum temperature, relative humidity and rainfall were also recorded at meteorological observatory of Punjab Agricultural University, Regional Station, Faridkot. Average on meteorological week basis CLCuD (%), per cent increase in CLCuD, whitefly population along with all the weather parameters was calculated. All possible simple and multiple correlations of CLCuD (%), percent increase in the CLCuD, whitefly population with different weather parameters were calculated. The multiple correlation analysis of the data indicated that there was significant positive correlation of the development of CLCuD with (1) minimum, maximum, mean temperature (2) maximum, minimum, mean relative humdity and (3) rainfall in varieties F846 and RS 921, in both the seasons, respectively. The correlation between disease development and whitefly population was also significant for both the years. So keeping in view all these aspects in a particular season, the suitable integrated disease management (IDM) strategies can be made to mange this malady in upland cotton.
