Diseases of Vegetables - Cauliflower

Blackleg
Leptosphaeria maculans

What's to look for?
Blackleg in cauliflower can be every bit as destructive as this disease is in susceptible canola cultivars. See canola for control procedures.

Photo: Howard

Picture description
Blackleg lesions.

Management strategy

Downy Mildew
Peronospora parasitica

What to look for?
Downy mildew can cause much of a field of milkwhite cauliflower curds to develop superficial discolored spots that renders the disease damage heads unmarketable.

Photo: Sweeney

Picture description

Management strategy

Whiptail
nutritional, molybdenum deficiency

What to look for?
Cauliflower is the most sensitive of crops to molybdenum (Mb) deficiency. Light sandy soils with pH levels close to or below pH 6 under conditions of high fertility can show severe Mb deficiency. Molybdenum is the only plant essential micronutrient that becomes less available as the soil acidifies--the opposite of copper, zinc and iron.

Photo: Evans

Picture description
Classical whiptail caused by Molybdenum deficiency.

Management strategy
Raise the soil pH above 6.5. Molybdenum is essential in the nitrogen reductase system in all plants and in the nitrogen fixation process in legumes.

Blackspeck

What to look for?
A physiological disorder in cauliflower common with the popular snowball cultivar.

Photo: Evans

Picture description
Black specks on the cauliflower.

Management strategy
Blackspeck could be due to nutrient imbalance. Tip burn and internal browning in cabbage and Chinese cabbage is due to the inadequate transport of calcium to rapidly growing tissues. Foliar spray, with calcium nitrate may control the problem or alternatively by a reduction in nitrogen fertilizer levels.

Wirestem
Rhizoctonia solani

What to look for?
Wirestem can be a seed problem where cauliflower or other cruciferous transplants are grown crowded together in unsterilized soil or seedling beds. This disease makes the seedlings unsuitable for transplanting since many of the affected plants will die or grow poorly.

Photo: Howard

Picture description
Classical wirestem--this is the same Rhizoctonia that causes seedling blight in canola.

Management strategy
Sterilized soil and seedbed drenches with fungicides will give good disease control.

Photographs and information assembled and prepared for ARD by Dr. Ieaun R. Evans Agri-Trend Agrology Ltd.

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For more information about the content of this document, contact Ron Howard.
This document is maintained by Shelley Barkley.
This information published to the web on November 25, 2003.
Last Reviewed/Revised on March 19, 2008.