Influence of Ethrel Upon Highbush Blueberry Fruit Ripening1

Ethrel (2-chloroethylphosphonic acid) applied as a foliar spray to blueberry two weeks before first harvest resulted in a significant increase in the percentage of the total yield of ripe fruit harvested in the first picking. The increase in fruit ripe at first picking occurred at a concentration of Ethrel as low as 240 ppm on the Weymouth variety, but for the Blueray variety 1920 ppm were needed to produce the same effect. Ethrel-treated berries were smaller and were less acid than control berries.