Boron Deficiency in Brussels Sprout
The first signs of boron deficiency are swellings on the stem and petioles, which later become suberized. The leaves are curled and rolled, and premature leaf fall of the older leaves may take place. The veins are frequently wrinkled. The growing point may die, followed by the development of two axillary buds leading to twinning of stems. If the deficiency becomes established before the sprouts are formed, very few develop. If the sprouts have started forming, they remain small, fail to heart, and have a loose appearance. The stem pith may be hollow and discolored.