Vegetable brassicas
Calcium and boron supplies are essential for the production of strong but elastic cell walls and to minimize crop disorders. Both nutrients have a key role to play in minimizing cracked stems, hollow heart and in providing good long term storage characteristics.
Fast growing conditions often brought on by heavy rainfall and warm weather after a cold period - tend to favor the occurrence of hollow stem. During these conditions, growth is rapid, but levels of both calcium and boron will be diluted in new tissues. As a result, cell walls lack strength and elasticity, leading to cell breakdown and cracking of stems.
Stem brassicas have hollow stems due to tissue cracking accompanied by a browning, corking or rotting of the damaged pith tissue. Brassicas are tolerant to high levels of boron and toxicity is rare.
In addition, too much forced growth through over-application of nitrogen - especially if this is out of balance with calcium and potassium availability - may create an inadequate supply of these elements and result in hollow stem.
Stem brassicas have hollow stems due to tissue cracking accompanied by a browning, corking or rotting of the damaged pith tissue. Deficiencies are most common on low pH and sandy soils. Brassicas are tolerant to high levels of boron and toxicity is rare.