Diseases of Vegetables - Broccoli

Downy Mildew
.Peronospora parasitica

This disease is common in wet, cool spring conditions causing leaf and curd discoloration. In Alberta, this fungus disease is also common on Argentine canola crops during cool wet weather in early to late June.

What to look for?
In cabbage heads the fungus infection may turn black and downgrade the cabbage value. Rutabagas and radish may have their roots affected resulting in black or brown internal discoloration. Both cauliflower and broccoli curds may be discolored by this fungus.

Photo: Sweeney	Picture description A gray unthrifty appearance of the growing crop. Superficially resembles herbicide spray drift.
. Photo: Sweeney	Picture description Large irregular spots on the leaves usually 1 cm or more in diameter. A gray wispy fungus visible on the leaf undersides obvious only in the early morning.

Management strategy
Avoid excessive overhead irrigation and spray with a fungicide at the seedling stage to reduce disease build-up.

Grow these crops as far away as possible from canola crops in order to avoid or reduce incidences of both diseases and insect pests.

Head Rot
Erwinia and Pseudomonas spp.

What to look for?
Wet waterlogged spots on the flower curds. Bacterial rots are common in cabbage, cauliflower and broccoli and losses in quality can be major. All of these bacterial diseases are soil-borne with some persisting in the soil for several years.

Photo: Sweeney

Picture description
One or more large water soaked spots on the curd florets not to be confused with looper damage.

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Management strategy
A 3 year rotation, disease free seed, balanced fertility, avoidance of excessive overhead irrigation and use of resistant cultivars when available are effective in 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.