Annual cropping of fruit trees is very important and to achieve this, flower or fruit thinning is practiced. By reducing the number of fruit on the tree, the remaining fruit will develop to the optimal size of higher quality and return bloom the
Abstract
Limb applications of 5% or 10% alkaryl polyoxyethylene alcohols (X-77 or X- 45) caused flower bud removal when applied to peach trees [Prunus persica (L.) Batsch] with a hand pump sprayer from first pink to 90% bloom. Applications made in late pink or bloom period caused a greater reduction in fruit set than earlier treatments. Applications made at 90% bloom caused some phytotoxicity to the tips of the first small leaves but did not affect the growth of the terminal vegetative primorida or of larger leaves produced on later terminals. Thinning appeared to be commercially acceptable when applied between 30% and 90% bloom. Fruit size at harvest was greater than the unthinned control. Airblast applications of 10% X-77 on the ‘Loring’ cultivar reduced fruit set about 40%.
Abstract
Beta-chloroethyl-methyl-bis-benzyloxy-silane (CGA 15281) was applied to 6 Eastern U.S. grown peach (Prunus persica (L.) Batsch) cultivars. Thinning response varied considerably with cultivar, timing, concentration and year. Unpredictable and commercially unacceptable leaf abscission occurred with most cultivars during the three-year period. Adequate thinning was achieved without excessive leaf abscission (10% or less) with only one treatment on 3 cultivars (‘Redhaven’, ‘Loring’, and ‘Sunhigh’) during the 3-year period. Reproducibility between years was not good. Unpruned trees or long 2-year-old limbs lost a greater portion of fruit at the base of shoots and on the interior of the trees than trees pruned to a uniform shoot length. The thinning response to CGA 17856 (an analogue of CGA 15281) was compared to the same rate of CGA 15281 on 5 cultivars. A tendency to greater leaf abscission was observed with CGA 17856.
Partial thinning of peach (Prunus persica L. Batsch) during bloom to 50% of the necessary level by hand, and followed by adjustment hand thinning at 42 days after full bloom (DAFB) was compared to a similar degree of thinning accomplished entirely at 42 DAFB by hand. Partial flower thinning altered the distribution of fruit by diameter, increasing the percentage of large diameter (≥62.0 mm) fruit harvested compared to unthinned trees or trees thinned entirely at 42 DAFB. Although shoot number per limb was not altered by thinning time, the distribution of shoots by length was affected, increasing the percentage of long shoots (≥20.0 cm). Compared to unthinned trees and trees thinned at 42 DAFB, partial flower thinning increased the subsequent development of flower buds per shoot and the number of flower buds per node. Number of flower buds on the proximal five nodes of shoots 15.0-30.0 cm in length was increased, although not on shoots 5.0-7.0 cm in length. Additional trials established that airblast spray application of AMADS was effective in achieving a similar level of thinning as that accomplished by partial flower thinning by hand in previous experiments. The degree of flower removal exhibited a linear response to chemical concentration. Fruit diameter on chemically flower-thinned trees was greater at adjustment thinning time, when compared to trees thinned by hand at 42 DAFB only. Distribution of fruit at harvest indicated a larger percentage of fruit >65.0 mm in trees which received partial flower thinning in comparison to trees thinned at 42 DAFB only. As a result, overall crop value was increased, based on the commercial processing peach price structure at the time of harvest. Chemical name used: 1-aminomethanamide dihydrogen tetraoxosulfate (AMADS)
108 ORAL SESSION 27 (Abstr. 564–571) Thinning–Fruits/Nuts
191 WORKSHOP 23 (Abstr. 1059-1061) Methods and Techniques for Testing Chemicals Used for Thinning Fruit Crops
108 ORAL SESSION 27 (Abstr. 564–571) Thinning–Fruits/Nuts
Hand-thinning, the physical removal of blossoms or immature fruit, can increase apple fruit size and quality at harvest. Maximal benefit of fruit size increase due to green fruit thinning occurred at or before 40 d after full bloom ( Batjer et al
Bloom and postbloom thinning is essential to managing yield and fruit quality in modern pear production systems. Much of the ‘Bartlett’ pear acreage in the western United States comprises well-established trees planted at low to medium density
growth and final size of the fruit ( Agustí and Almela, 1984 ; Agustí et al., 2003 ; Mesejo et al., 2003 ). To decrease this competition, “thinning,” which is the removal of some flowers and/or fruit in the earliest development stage, is a common