Physiological Disorders

Buttoning and Lack of Heads (Broccoli and Cauliflower)

Buttoning refers to premature formation of broccoli or cauliflower heads. It occurs when transplants do not have enough leaves to support a head of a marketable size. Buttoning is most common when young plants are transplanted prior to hardening off or into suboptimal field conditions. Early varieties and older transplants are most susceptible. Other stress factors such as low fertility, low moisture micronutrient deficiencies, or disease and insects can also be causes. Strong healthy plants lacking heads can occur due to periods of extremely warm weather (days over 86ºF and nights over 77ºF).

Bracts (Leaves) in Cauliflower or Broccoli Heads

High temperatures and/or low soil moisture can result in the formation of bracts, small leaves, between segments in the heads of cauliflower and broccoli. Choose heat-tolerant varieties to avoid bract formation in heads. Maintain uniform soil moisture.

Brown Bead (Broccoli)

The disease is caused by a combination of environmental and genetic factors. Reduced calcium uptake due to low transpiration rates under extended wet conditions followed by warm temperatures and rapid growth can result in this condition. Brown bead occurs when individual flower buds abort under warm, dry conditions. It is recomended to grow less susceptible varieties. It is best to grow a mix of varieties with different maturation rates to reduce the risk of losing the entire crop due to adverse weather conditions.

Oedema of Cabbage

Oedema (edema) 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.

Ricing or Fuzziness of Heads (Cauliflower)

The development of cauliflower curds that appear fuzzy is called ricing. Ricing can be caused by exposure of the developing curds to high temperatures or direct exposure to sun, rapid growth after head formation, high humidity, and high nitrogen fertility.

Tipburn

Tipburn is a result of localized calcium deficiency in leaf tips, which can occur due to irregular soil moisture content or low plant transpiration rates even when soil calcium levels are high. Providing consistent irrigation and taking measures to prevent root-compromising disease can help reduce incidence of tipburn.

Yellow Beads in Broccoli

Yellowing of florets may be due to an over-mature head, high storage temperatures after harvest, or exposure to ethylene. 

Hollow Stem (Broccoli and Cauliflower)

This disease is typically associated with boron deficiency, but may also occur when excessive nitrogen encourages rapid growth. Tissue or soil testing can detect boron deficiency. Brown discoloration of heads may accompany this condition.