Interaction of NAA with Accel and Promalin on Fruit Size in `Delicious' and `Empire' Apples

• Published in: HortScience Vol. 30; no. 4; p. 765
• Main Authors: Bukovac, Martin J, Black, Brent L, Hull, Jerome, Jr
• Format: Journal Article
• Language: English
• Published: 01-07-1995
• ISSN: 0018-5345; 2327-9834
• DOI: 10.21273/HORTSCI.30.4.765C

NAA and Accel are used for fruit thinning of apples. However, when combined, many small (<65 mm) fruit were produced in `Delicious'. We extended our studies using Redchief `Delicious' and `Empire', and, since BA is common to both Accel and Promalin, to study the effect of NAA-thinning sprays on Promalin-treated Redchief trees. NAA (10–15 mg·liter
–1
) and Accel (25–100 mg·liter
–1
) were applied to Redchief and `Empire' at 100-mm king fruit diameter (KFD). NAA interaction with Promalin was studied using Redchief. Promalin (1.5 pt/A) was applied as a single spray (80% king bloom, KB) and as a split application (0.75 pt/A, 80% KB and repeated at 10-mm KFD) with NAA (15 mg·liter
–1
) at 10-mm KFD. In `Delicious', 2% to 9% of the fruit from Accel-treated trees was <65 mm in diameter, compared to 11% for NAA alone. However, when NAA was applied with Accel, 22% to 30% of the fruit was <65 mm and percentage of large fruit (75 mm+) was reduced by 24% to 36%. There was no strong interaction for fruit size in `Empire', but the combination decreased yield. NAA applied to Promalin-treated `Delicious' increased percentage of small fruit dramatically (14% to 25%). No increase in small fruit was observed with Accel of Sevin.