Southeast Regional Blueberry Horticulture and Growth Regulator ...

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Fertilizer recommendations for North Carolina:Propagation bedsApply 1 lb. diammonium phosphate (18-46-0) dissolved in 4 gallons water per 100 sq. ft. of bed beginning when cuttings are well-rooted (July 1-15)and repeat every 2 weeks until mid-August.First yearAfter the first flush of growth apply 40 to 80 lbs. of 14-28-14 per acre and repeat every 4 to 6 weeks until mid-August. Extend application intervalduring dry periods until rainfall has totaled 4 inches. Based on 1360 plants per acre.Second yearDouble first year amount when new growth begins in the spring. Follow the first year timing and rate schedule for the rest of the season.Bearing plantsApply 100 to 150 lbs of 14-28-14 prior to blossoming and an additional 50 to 75 pounds 4 to 6 weeks later (early May). On sandy soils or if moregrowth is desired, apply 50 pounds ammonium nitrate after harvest. Apply 50 pounds per acre of diammonium phosphate 18-46-0 in mid-August tomaintain plant vigor if phosphorus is low or leaching has been severe.Adjustments for rabbiteye blueberriesThe above recommendations are based on tests and responses of highbush blueberries. Rabbiteye blueberries require less fertilizer, especiallynitrogen. For the first 3 years, rabbiteye can be fertilized the same as highbush in order to get maximum growth. Once plants reach about 5 feet tall,the rates should be reduced. On soils with more than 2% organic content, little or no nitrogen is required. When bushes reach 5 feet tall on soils withmore than 2% organic content, apply 50 to 100 pounds per acre of 14-28-14 prior to blossoming. Make additional applications only if more growthor better bush color is desired. Rabbiteye bushes with foliage that is a medium green (slightly yellow-green) are often more productive than bushesthat are a deep green. The deep-green bushes produce excessive vegetative growth (shoots) and fewer flower buds. Rabbiteye bushes respondrapidly to nitrogen fertilization if the leaf color gets too yellow. Green color will often return within 10 to 14 days after applying 50 pounds per acreof ammonium nitrate. The mid-August application of diammonium phosphate is generally beneficial also for rabbiteye in order to stimulate a healthyroot system for the winter. Rabbiteye bushes require more adjustments in fertilization depending upon soil organic content and rainfall than do
highbush plants. In some tests, on soils with more than 2% organic content, production has been equal or greater with no fertilization than with anyfertilizer combination.NOTE: The 14-28-14 fertilizer is a blend of diammonium phosphate, ammonium nitrate (33-0-0) and potassium chloride (0-0-60). Otherformulations are available but this one is probably the most desirable since no filler is required. The same ingredients can be blended into a 14-14-14analysis if soil phosphorus is in the medium or high range. Use proportionally more fertilizer if an analysis lower than 14-14-14 or 14-28-14 is used.Apply actual copper at the rate of 1 pound each year or 5 pounds once every 5 years. Take soil samples at least once each year to determinephosphorus level and changes in pH.Lime at the rate of 500 lbs/acre (about ½ lb/bush) has given a positive response on soils when the pH was below 3.6. Avoid excessively liming since1000 lbs/acre has been detrimental in all cases.
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Page 8 and 9: Overview of Blueberry Growth Regula
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Southeast Regional Blueberry Horticulture and Growth Regulator ...

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