Southeast Regional Blueberry Horticulture and Growth Regulator ...

Overview of Blueberry Growth Regulators(Read detailed information before purchase or use)ProblemPoor Spring leaf development anddelayed flowering of some southernhighbush and rabbiteyes, delayed harvestPoor fruit set of rabbiteye blueberries inpoor pollination situations or years;Poor fruit set following partial freezedamage of rabbiteye flowersManagementOptionsDormex(50%hydrogencyanamide)Gibberellicacid -ProGibb 4%liquidconcentrateor GibGro 4LS or Gibbex4%Amount ofFormulationper AcreTypically1 ½%Dormex plus1 pint peracre of nonionicsurfactant in50 gallons ofwater24-32oz./acre (4%gibberellicacid) or 24-32 gramsgibberellicacid/acreapplied twice(total of 48-64 oz./acre inmost cases)Effectiveness (+)or Importance (*) REI PHI Comments++++ 72certain cultivars hours NA++++ 12hours40daysNot recommended for use in NorthCarolina. This is a material that must beused with caution.Enclosed cab tractor required forapplication.Will kill flower buds if applied after budswell. Application must be based on buddevelopment. Typical application dates forsouthern highbush in south Georgia are lateDec. or early Jan. Rabbiteyes applicationsare usually in late Jan. or early Feb. Useonly on a small scale until you gainexperience with the material. Do not applywithin 14 days of oil application or within30 days of copper fungicide application.First application: When at least 40-50% ofthe blooms are open. About 10% of theflower petals should have fallen. Secondapplication: 10-18 days later.1. min. of 40 gal. water/acre.2. Add surfactant.3. If solution is alkaline (pHgreater than 8.0), lower thepH with a buffering agent.4. Apply at night or duringslow drying conditions