SUMMARY
The growth regulator CPPU [N-(2-chloro-4-pyridyl)-N′-phenylurea] has recently been shown to increase both fruit set and berry size in rabbiteye blueberries (Vaccinium ashei Reade) in Experiment Station research plots. In order to validate these findings, several field experiments were conducted during 2001 and 2002 on commercial farms across south Georgia with the rabbiteye cultivars ‘Climax’ and ‘Tifblue’. The standard CPPU concentration used was 10 mg/L applied at 10 to 18 days after 50% bloom. In 2001, most CPPU applications were with a back-pack sprayer, but in 2002, applications were made using commercial air-blast sprayers. In general, results from both years showed a positive benefit of CPPU with respect to fruit set, especially for the cultivar ‘Climax’. Depending on location and year, fruit set was increased by as much as three-fold for ‘Climax’. Fruit set increases were also observed for ‘Tifblue’, but the effect was less pronounced. With respect to berry size, CPPU generally increased ‘Climax’ size by 12 to 22% in both years. Berry size increases were observed for ‘Tifblue’, although, responses were not as consistent as for ‘Climax’. A slight delay in fruit ripening sometimes occurred for CPPU treated plants. These results suggest that CPPU may be useful for increasing yield of rabbiteye blueberries by increasing fruit set and/or berry size.