Diseases of Vegetables - Cabbage

Blackleg.
Leptosphaeria maculans

What to look for?
The same blackleg that adversely affects canola crops is a destructive fungal pathogen on cruciferous vegetables. It is likely that the present virulent strain of blackleg on canola was introduced to Canada via cole crop infected vegetable seed.

Photo: Howard

Picture description Blackleg lesion with pepper spots.

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Management strategy
For blackleg control check under canola.

Blackspeck

What to look for?
This disease or disorder occurs in stored cabbage. The disorder is not caused by infections, bacterial, fungal or viral infection. The distinct black specks that are found even on the inner leaves maybe related to a nutritional disorder or as a consequence of high natural levels of ethylene in the storage environment.

Photo: Evans

Picture description Blackspeck lesions on cabbage leaf.

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Management strategy

White Rust
Albugo candida

What to look for?
White rust is usually of minor importance on most of the cabbage family but it can be a problem on Chinese cole crops related to Brassica campestris (B.rapa).

Photo: Evans

Picture description White rust lesions on cabbage species.

Management strategy

ClubRoot

Clubroot is caused by Plasmodiophora brassicae. This very destructive disease was identified on broccoli, cabbage and cauliflower in several backyard gardens in Alberta in the late 1970's. Counties with confirmed clubroot from surveys conducted from 2003-2007:

Sturgeon	Camrose	Flagstaff	Leduc
Newell	Wetaskiwin	Barrhead	Strathcona
Lac Ste. Anne	Westlock

All cruciferous crops are usually susceptible as well as cruciferous weeds.

Fusarium Wilt

Fusarium wilt (yellows) caused by Fusarium oxysporum f. sp. conglutinans
This is a seed- and soil-borne fungus that is extremely destructive on cruciferous crops. Most cultivars of cabbage, cauliflower, broccoli, for example have a moderate to high resistance to this disease.

Rhizoctonia

Rhizoctonia (Rhizoctonia solani) wire stem , damping-off. Common in cold dry springs or when cole crop seedlings are grown in short or nonexistent rotations. This is the same disease that affects canola crops so it advisable to avoid canola cropland.

Cottony Soft Rot

Cottony soft rot (Sclerotinia sclerotorium) can be destructive on late grown cabbage especially in wet or humid falls. Leaves in contact with the soil may be the initial source of infection. Rot may occur in storage not only in cabbage but in rutabaga, turnip, carrots and parsnips. The infected heads show an obvious white cottony rot. Sunflowers, snap beans, and canola crops often are the source of infection in the field.

Nutritional Disorders

Cole crops require high levels sulphur for effective protection just as we expect for canola crops.

Boron deficiency--water soaking of cauliflower heads, stem cracks, and brown discoloration of root crops, especially in coarse sandy soils. Apply boron fertilizer at 1-3 lbs per acre rate of actual boron.

Molybdenum deficiency causes whiptail in cruciferous crops especially under high fertility in coarse sandy soils or soils with pH levels below pH 6. Growing points maybe be lost or distorted in cole crop seedlings. Sodium molybdate at ounces (grams) per acre or as a foliar mixed with fertilizer or even as a seed treatment are very effective in controlling this deficiency problem.

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

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