Boron (B) deficiency is a rare disorder affecting plants growing above a granite bedrock, which is low in boron. Boron may be present but locked up in soils with a high pH, and the deficiency may be worse in wet seasons.
Symptoms include dying growing tips and bushy stunted growth. Crop-specific symptoms include;
- Beetroot- rough, cankered patches on roots, internal brown rot.
- Cabbage- distorted leaves, hollow areas in stems.
- Cauliflower- poor development of curds, and brown patches. Stems, leafstalks and midribs roughened.
- Celery- leaf stalks develop cracks on the upper surface, inner tissue is reddish brown.
- Pears- new shoots die back in spring, fruits develop hard brown flecks in the skin.
- Strawberries- Stunted growth, foliage small, yellow and puckered at tips. Fruits are small and pale.
- Swede (rutabaga) and turnip- brown or grey concentric rings develop inside the roots.
Boron deficiency can be avoided by improving the moisture retaining capacity of light soils, and ensuring pH is kept below 7. Borax can be raked into the soil at 35 g/m² (1 oz/yd²).
Other physiological plant disorders include;