Boron Deficiency in Rubber Trees
Boron deficiency in rubber trees would be expected only in soils of extremely low boron status as the rubber tree is efficient in absorbing boron. It is particularly sensitive to excess boron supply. Boron-deficient leaves are distorted, reduced in size, and somewhat brittle. The leaf deformation does not follow any consistent pattern and there is no loss of color. On young unbranched trees, the first sign of boron deficiency is to be found in the younger, upper stories of leaves on the plant, which will not be separated by any discrete internode. The individual stories cannot be distinguished, resulting in the “bottle brush” appearance of the stem. When boron deficiency is severe, the apical meristem may die and axillary meristems develop prematurely.