ARS | Publication request: Effects of Hydrogen Cyanamide Application Rates and Timing on Fruit and Foliage of 'Climax' Rabbiteye Blueberry

Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: November 15, 2001
Publication Date: April 30, 2002
Citation: Stringer, S.J., Spiers, J.M., Braswell, J., Marshall, D.A. 2002. Effects of Hydrogen Cyanamide Application Rates and Timing on Fruit and Foliage of 'Climax' Rabbiteye Blueberry. Acta Horticulturae (ISHS). 574:245-251.

Interpretive Summary: A field study was conducted to evaluate the effects of flower bud pruning or utilizing differing rates of hydrogen cyanamide, on development of vegetative and floral buds, as well as on leaf area, vegetative coverage, fruit damage and development, and yield. In this study, hydrogen cyanamide applications increased the total leaf area of leaves arising from terminal leaf buds and also the overall vegetative coverage. Results of this study suggested that in years in which chilling hours are sufficient to result in balanced floral and vegetative bud break and development, cultural practices for promoting the development of leaves of ‘Climax’ may be of little benefit for enhancing fruit production for that particular season. Results also suggested that applications made too late in the season, when as few as 10% of flower buds are in stage three of development, excessive flower bud injury and yield reductions may occur. This information can be used by other scientist, and extension workers in the blueberry industry to help growers increase their yield and production in years that lack sufficient chilling.

Technical Abstract: A field study was conducted to evaluate the effects of flower bud pruning or utilizing differing rates of hydrogen cyanamide, on development of vegetative and floral buds, as well as on leaf area, vegetative coverage, fruit damage and development, and yield. In this study, hydrogen cyanamide applications increased the total leaf area of leaves arising from terminal leaf buds and also the overall vegetative coverage. Results of this study suggested that in years in which chilling hours are sufficient to result in balanced floral and vegetative bud break and development, cultural practices for promoting the development of leaves of ‘Climax’ may be of little benefit for enhancing fruit production for that particular season. Results also suggested that applications made too late in the season, when as few as 10% of flower buds are in stage three of development, excessive flower bud injury and yield reductions may occur. However, the effects of these particular treatments on foliage and fruiting during the following season are yet to be determined.