SummaryWe 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 subgroup 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, increasing to a maximum near the estimated time of bunch initiation, then decreasing 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 plants were not significantly different. However, BSV‐Cav infection resulted in an 18 day delay in harvest, causing a 6% reduction in yield per annum. In the ratoon crop, the mean bunch weight of infected plants was 7% less than 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 favourable conditions typical of the tropical Australian banana industry, the effects of BSV‐Cav infection on the growth and yield of Cavendish bananas are small.

This study examined the effects of bunch trimming and leaf removal on rate of bunch filling, severity of the maturity bronzing fruit peel disorder, and other yield and quality paramaters. There were 4 levels of leaf removal (4, 7, 10, 13 leaves retained) and 4 levels of bunch trimming (male bud retained, male bud removed, male bud and 2 hands removed, male bud and 4 hands removed) imposed on banana bunches at flowering. The experiment was carried out at South Johnstone, North Queensland. The 320 plants in the trial produced a range of fruit-filling rates that were largely unrelated to the imposed treatments. With the exception of the duration of fruit filling and extra large fruit weight, leaf removal and bunch trimming acted independently on the attributes measured. Leaf removal reduced maturity bronzing and bunch trimming increased it. Increased bronzing was associated with increased finger length, possibly due to epidermal cells in the fruit peel elongating beyond their elastic limit. Bunch trimming reduced bunch weight and but did not improve the quantity of extra large fruit. Leaf removal reduced bunch weight when <10 leaves remained, due largely to a reduction in finger length throughout the bunch. Fruit greenlife was also reduced by leaf removal. Therefore, the reduction in maturity bronzing achieved by leaf removal is of no immediate benefit to growers. Removal of the male bud increased bunch weight due to an increase in finger length. Dry weight analysis indicated that the male bud represented a significant competing photosynthetic sink. For maximum yield of quality fruit, growers should remove the male bud, practice no bunch trimming, and ensure the retention of at least 9-10 leaves from flowering to harvest.

Summary. Yield and plant characteristics of the longer fingered selection ‘J.D. Special’ were compared with cv. Williams which is the industry standard. Data from 2 sources (‘experiments’), including on-farm trials at 6 sites in Queensland, Australia, (experiment 1) and an experiment at the Queensland Department of Primary Industries South Johnstone Research Station investigating maturity bronzing (experiment 2), were utilised for this report. The fruit on hands 2 or 3 of J.D. Special were on average 10–15% longer in the crops investigated. Increased finger length occurred along the entire bunch resulting in 15 and 6% more extra large fruit for J.D. Special than for Williams in the plant crops of experiments 1 and 2, respectively. Similar differences were observed in the ratoon crops. Bunches of J.D. Special were 19–22% heavier than Williams for plant crops. A combination of greater fruit length and more hands per bunch in J.D. Special contributed to their greater bunch weight. J.D. Special took longer from planting to harvest (average of 17days) but yields/unit time were still 17–19% greater than Williams. Plants of J.D. Special were more prone to bunch losses with 2 cases of 35 and 45% loss compared with no losses for Williams, the losses being largely due to wind damage. This susceptibility of J.D. Special is presumably due to its greater plant height and heavier bunch weight. Fruit greenlife of J.D. Special was 17% less than Williams in the one crop investigated, although this was not significant (P>0.10).