Effects of NAA and Carbaryl on Fruit Set and Return Bloom for Some Apple (Malus domestica Borkh.) Cultivars

This research was conducted in 1997 and 1998 to investigate the effects of naphthalene acetic acid (NAA) (5, 10, and 15 ppm), Carbaryl (1-naphthyl N-methylcarbamate) (750, 1000, and 1250 ppm), and NAA + Carbaryl (5 + 750, 7.5 + 750, and 10 + 750 ppm) applications on the return bloom of some standard apple (Malus domestica Borkh.) cultivars grafted on MM106 rootstock. Of these applications, 750 ppm Carbaryl for 'Starkspur Golden Delicious', 1250 ppm Carbaryl for 'Granny Smith' and Starkrimson Delicious', and 5 ppm NAA for 'Jonagold' increased the mean number of flower buds significantly, compared with the control treatments. The other treatments of Carbaryl, NAA, and NAA + Carbaryl also increased the mean number of flower buds in a nonsignificant sense with a few exception. A negative correlation between the final fruit set and the mean number of next year's flower buds was found for three cultivars. The correlation coefficients were r = -00.5150 (P < 0.05), r = -0.6999 (P < 0.05), r = -0.0335 for 'Starkspur Golden Delicious', 'Granny Smith', and 'Jonagold' cultivars, respectively. However, this relationship was positive and nonsignificant for ` Starkrimson Delicious' (r = 0.1980). (C) 2005 by The Haworth Press, Inc. All rights reserved.