Submitted to: American Society of Horticulture Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 9, 2007
Publication Date: September 6, 2007
Citation: Black, B., Ehlenfeldt, M.K., Martin Jr, R.B. 2006. Suppression of flowering in "bluecrop" highbush blueberry. American Society of Horticulture Science Meeting. 55:8269-8274.
Precocious varieties of highbush blueberry may overcrop during the first few seasons in the fruiting field, adversely affecting plant establishment. Reducing or preventing bloom in the nursery and during establishment would be beneficial in preventing early cropping and reducing the risk of infection by pollen-borne viruses. We investigated the efficacy of foliar applications of ProVide®, (Valent BioSciences) a commercial GA4+7 formulation, for suppressing flower bud initiation in blueberry. One-year-old rooted cuttings of ‘Bluecrop’ were obtained from a commercial nursery and established in 11-liter pots at the Blueberry and Cranberry Research Center, Chatsworth, New Jersey. Dilute foliar applications of Provide® were made at concentrations ranging from 50 to 400 mg a.i./L, ranging from 7 July 2004 to 1 Sept 2004, with 10 replicate plants per treatment. Flower bud counts were made the following spring. A separate experiment was initiated in 2005, with concentrations of 200 and 400 mg a.i./L applied in August and September. For the 2004 study, the greatest flower bud suppression resulted from repeat applications at 400 mg a.i./L. Weekly applications from 7 July to 1 Sept resulted in a 70% reduction in flower bud number, whereas three weekly applications from 18 Aug to 1 Sept reduced flower bud number by >88%. Neither treatment significantly reduced total bud numbers (vegetative + floral) compared to untreated and water-sprayed controls, indicating that the effect did not result from reduced growth. Results for the 2005 treatments will also be presented.