Boron shortage resulted in limited growth, terminal dieback, pronounced bark lenticels and bark splitting; waxy, thick, brittle foliage; early defoliation; early leaf development after dormancy; fewer flower buds; longer blooming period; reduced pollen viability; poor fruit set and quality; fruit cracking and dry brown corky spots adjacent to the pit. Boron excess caused leaf distortion, shoot dieback, pit splitting, and leaf bud mortality after dormancy; increased break of lateral shoots; fewer flower buds; reduced pollen viability and fruit set; and faded flowers and anthers. Correction of B shortage or excess resulted in normal growth, flower bud formation, pollen viability, and fruit set and quality. Based on growth response, symptom expression and fruiting, the B content of peach leaves can be correlated in the following manner: severe deficiency, less than 10 ppm; deficient, 11 to 17 ppm; low, 18 to 30 ppm; optimum, 31 to 59 ppm; high, 60 to 80 ppm; and excess, 81 to 155 ppm. There was a positive correlation between mean B content of leaves and that of the fruits. The symptoms of B injury suggested the following classification of the B status in the fruits; deficient, less than 10 ppm; normal, 11 to 29 ppm; and excess, 44 to 124 ppm. An application of fritted trace elements3 at the rate of 20–160 lb/A to sand in the crocks gave good vegetative growth the first season but was inadequate to support normal growth and fruiting the second season. An additional application of 40 or more lb/A near the end of the second growing season afforded normal growth, fruiting and fruit quality for the third season.
No takes yet. Share an insight, caveat, or question.
Kamali et al. (1970) studied this question.