ISHS Acta Horticulturae 179: V International Symposium on Growth Regulators in Fruit Production
CROPPING CHARACTERISTICS OF BEARING APPLE TREES ANNUALLY SPRAYED WITH PACLOBUTRAZOL (PP333) |
| Author: | L.D. Tukey |
| Abstract:
Bearing trellis-row sections of apple cultivars on M.9 or M.26 were sprayed annually or less frequently with a dilute aqueous solution of paclobutrazol as PP333, 50WP. Single spray treatments ranged from 500 to 1000 ppm, and sequential treatment sprays were at 250 ppm. These were scheduled at petal fall and/or at 3 week intervals. After 2 years, reduced tree vigor, leaf and fruit size, and yield were noted in some plots. Lowering the recharge rate on high concentration plots was only moderately successful in restoring quality yield. Foliar sprays of GA at a low concentration at weekly intervals, beginning at petal fall, appeared to restore tree and cropping vigor, although the spur habit induced by the retardant was largely retained. Stionic vigor influenced results, with weaker stions more susceptible to overdose effects than strong stions. A cultivar's biennial bearing habit was often intensified. The most satisfactory schedule over time was 750 ppm at 3 or 6 weeks after petal fall. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
