Apple tree budbreak promoters in mild winter conditions.

摘要

The technical and economic efficiency of new budbreak promoters, i.e. inorganic hydrogen compounds (Erger), Busan 30 ((2-thiocyanomethylthio) benzothiazole 30%), calcium polysulfide and TDZ [thidiazuron] + mineral oil (Lift), as alternatives to Dormex were studied in 17-year-old orchards of apple (Gala/M.7 and Fuji/M.7) in Brazil. Dormex and Erger advanced budbreak and blooming in relation to the other treatments. The percentage of budbreak on laterals was greater when treated with Erger (5-7%) + calcium nitrate (5-10%) than with Dormex + mineral oil. Calcium polysulfide showed low efficiency in breaking lateral buds. The best break of lateral buds would result in more flowers for the following season. This was more evident with Erger treatments. Erger reduced fruit set in Gala and, to a less extent, in Fuji. Lift was efficient in stimulating the break of lateral buds, but it reduced leaf size in the current year, and resulted in very small fruits in the following growing season. Among the promoters, Erger was the most promising for commercial use under the climatic conditions of southern Brazil.