Influence of temperature and relative humidity on population dynamics of thrips and leaf curl disease incidence in blackgram genotypes

The insect pests and diseases of blackgram continue to pose a serious threat to the plant growth and yield. The sucking pests in blackgram are economically most important that not only cause the direct damage by feeding but also by transmission of different viral diseases. Sucking pest complex in blackgram include an array of sucking pests out of which thrips, whitefly and aphids are the most important. The leaf curl disease caused by GBNV in blackgram is transmitted through thrips. A study was conducted involving 25 blackgram genotypes to screen them against leaf curl disease. The results obtained from the study indicated that the leaf curl disease incidence (%) and thrips population (Number plant-1) varied significantly among the genotypes. Late sowing of the crop coincided with higher temperatures, lower relative humidity and high vector population resulting in higher leaf curl disease incidence. The correlation studies indicated that the leaf curl disease incidence (%) was negatively associated with the mean and morning relative humidity (%) and positively associated with mean, maximum and minimum temperatures.