Physiological Disorders

Oedema of Cabbage

Oedema is a physiological response of the plant to excessive soil moisture during periods of cool nights and warm, humid days. Many small scabby lesions form on the underside of the cabbage leaves. Avoid irrigation during times when day-night temperature variations are great. Oedema may be confused with thrips damage.

Head Rot and Brown Beading (Broccoli)

Both problems are caused by several factors. Problems with calcium uptake combined with rapid growth can result in either condition, even when soil calcium levels are high. Head rot results from bacteria breaking down the tissues under wet conditions, and brown beading results from individual flower buds aborting under dry conditions. Extended periods of wet or dry conditions during warm temperatures give rise to rapid plant growth while calcium uptake is diminished due to poor transpiration rates in the plants. Mixing varieties based on rate of maturity offers growers the only practical defense against either head rot or brown beading. Select a later-maturing cultivar to be harvested along with your regular cultivar for that part of the growing season when problems have typically occurred. The slower growth rate of the later maturing cultivar may prevent your total loss of market position if conditions are not completely overwhelming.