Searching for new possibilities of bloom delay in apricots

Late frosts threaten the yield in many apricot growing regions. Bloom delay is one of the possible passive protection methods. Ethephon (2-chloroethylphosphonic acid) is the best known efficient chemical bloom delayer. However, its use can have some negative side effects. Thus, an efficient and safe substitute has yet to be found. The objective of our experiments was to simply test the delaying efficiency of some active ingredients and methods in apricot (Prunus armeniaca L.) orchard and compare them with ethephon as a standard. 1-Aminocyclopropane 1-carboxylic acid (ACC), abscisic acid (ABA), soybean oil, and white latex painting were used individually or in combinations in two seasons and the results compared with autumn application of ethephon. When used alone, the ethephon at 100 ppm was the most effective compound in both seasons. The bloom delay was even increased by combining its application with winter white paint or with white paint and early spring soybean oil sprays. Autumn application of ACC alone at 100, 1000, and 2000 ppm concentrations did not lead to any delay unless combined with white paint or with white paint and soybean oil. ABA at 1000 ppm concentration also did not cause any delay. Double application of 8% soybean oil at early spring alone had similar effect as ethephon at 100 ppm. White latex paint alone had minor effect. The tested methods did not show significant delays when used alone but their combinations appears promising.