Analysis on the spread of a whitefly-transmitted geminivirus on tomato in Malaysia

Epidemics of leaf curl virus (LCY) on two tomato varieties were monitored in four cropping systems. The initial virus symptom was detected at 47 days after transplanting (DAT) in all plots. Between the two tomato varieties, the variety MF08 was more tolerant against LCY than MTI. The slowest apparent infection rate (AIR) and the smallest Area Under Disease Progress Curve (AUDPC) of the disease were recorded on tomato planted under wooden rainshelter with netting.Highest AIR and AUDPC were found on tomato planted under open field conditions. The use of reflective plastic mulch reduced and delayed the onset of LCY on tomato. The spatial distributions of symptomatic plants were mapped and analysed using SADIE. Analyses of the spatial distribution showed that at 47 DAT, the disease was random but became clustered at 75 DAT, demonstrating for the first time that the LCY transmitted by the whitefly, Bemisia tabaci epidemic was polycyclic. There is evidence that the disease moves outwards from the sites of initial infection to other healthy plants. The associations between spatial structure of disease incidence between 47-75 DAT are statistically significant (p 0.05).