Chemical Thinning of Peaches
V. On the Fruit Drop During the Period Between the End of Drop by Peach-thin and Final Hand Thinning
1972 Volume 41 Issue 1 Pages 37-41
Details
1972 Volume 41 Issue 1 Pages 37-41
As previously reported, fruit drop by Peach-thin is over about 25 days after full bloom, and final hand thinning is used to be done about 30-40 days after full bloom. This report concerns the fruit drop during the period between the end of drop by Peach-thin and the final hand thinning.
1. The experiments had been conducted on three groups of peach trees (cultivar Hakuho); Group one was consisted of 4 trees of 13-16 years old during 1962-1965, group two 3-6 trees of 4-7 years old during 1962-1965, and group three 4-8 trees of 4-7 years old during 1967-1970. In every season, 200ppm solution of Peach-thin was sprayed two or three days after full bloom. In addition, twice spraying of 200 ppm solution two and four days after full bloom and 400ppm spray two days after full bloom, were applied in some cases. As the results of these experiments, significant differences were not found in the amount of the drop in this period between Peach-thin sprayed branches and unsprayed branches, and between the tree ages ranging 4-7 years old, while the amount of drop varied with the years. Therefore, it may be concluded that the drop during this period is neither affected by Peach-thin spraying nor by tree age, but is affected by the climatic conditions of the year. Throughout these experiments, the range of fruit drop rate was from 0% to 25%, and the population mean was 10.7±1.5% at the 95% confidence coefficient. As proper fruit setting at the hand thinning time is 16-18%, desirable fruit set at the end of drop by Peach-thin spraying may be 26-28% (approximately 25-30%), when the amount of drop in this period is expected to be about 10%.
2. All the flowers, which were cut off their styles at their bottom in their full bloom in order not to be fertilized, dropped during the period from 25 days to 40 days after the full bloom. Therefore, it is assumed that the drop in this period may be the drop of fruits which did not have chance to be fertilized. A part of fertilized fruits seems to be thinned by Peach-thin spraying.
