The effect of Banana streak virus on the growth and yield of dessert bananas in tropical Australia

We have examined the effect of a strain of Banana streak virus (BSV-Cav) on the growth and yield of dessert bananas (Musa AAA group, Cavendish subgrou p cv. Williams) in north Queensland, Australia. Healthy and infected plants were compared in a replicated field experiment over plant and first ratoon crops. In both crops, symptom expression followed a similar pattern, incre asing to a maximum near the estimated time of bunch initiation, then decrea sing in the period prior to bunch emergence. There was no evidence of plant -to-plant spread of virus, but the rate of transmission through suckers was 100%. In the plant crop, the mean bunch weights of healthy and infected pl ants were not significantly different. However, BSV-Cav infection resulted in an 18 day delay in harvest, causing a 6% reduction in yield per annum. I n the ratoon crop, the mean bunch weight of infected plants was 7% less tha n that of healthy plants, and the interval between the harvest of plant and ratoon crops was delayed by 9 days, resulting in a 11% reduction in yield per annum. Also, the mean length of fruit from infected plants was 5% less than that of healthy plants, resulting in a smaller percentage of fruit in the extra large size category. We conclude that in horticulturally favourab le conditions typical of the tropical Australian banana industry, the effec ts of BSV-Cav infection on the growth and yield of Cavendish bananas are sm all.