Diseases of Red Clover

Photo: Howard

Picture description
Blight damaged leaves.

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Management strategy
No control procedures.

Spring Black Stem
Ascochyta meliloti

What to look for?
Spring black stem of red clover is similar to the spring black stem of alfalfa. Black lesions develop on the stems, petioles, pods and leaves. Cool moist weather favours disease development.

Photo: Howard

Picture description
Distinct black lesions on the stems.

Management strategy
Harvest early to avoid excessive leaf drop.

Cercospora Leaf Spot / Summer Black Stem
Cercospora sp.

What to look for?
Cercospora sp., in particular Cercospora zebrina causes summer black stem of clover. Leaf lesions are grey to tawny. Infected leaves drop off. Pod stalks are reddish brown to black.

Photo: Howard

Picture description
Distinct grey leaf lesions.

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Management strategy
Harvest early to avoid heavy leaf loss.

Northern Anthracnose
Kabatiella caulivora (Aureobasidium caulivorum)

What to look for?
Common in red clover in cool humid weather. Sunken lesions develop on stems and petioles. Leaves and flower heads fall over, wilt and die. Plant appears blackened when disease is severe.

Photo: Howard

Picture description
Black lesions on stems.

Photo: Ellis

Picture description
Black lesions on stems and leaves.

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Management strategy
Control via crop rotation and resistant cultivars.

Powdery Mildew
Erysiphe polygoni

What to look for?
A very common disease of red clover. Epidemics in hot dry conditions lower hay quality.

Photo: Howard

Picture description
Distinct mildewy appearance of infected crops.

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Management strategy
Early cutting reduces disease losses. Resistant cultivars are available.

Pseudopeziza Leaf Spot
Pseudopeziza sp.

What to look for?
Similar to the Pseudopeziza leaf spot in alfalfa and sweet clover.

Photo: Howard

Picture description
Distinct black spots on clover leaves.

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Management strategy
Early cutting reduces disease losses.

Rust
Uromyces trifolii

What to look for?
This disease arrives very late in the growing season to be much of an economic problem.

Photo: Howard

Picture description
Numerous distinct brown rust pustules on leaves.

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Management strategy
No control.

Sclerotinia Stem Rot
Sclerotinia trifoliorum

What to look for?
As with other clovers, this disease can be severe on plants that have been well covered with snow that persists late into spring. Under such circumstances, heavy stand loss can occur as soon as the snow melts.

Photo: Ellis

Picture description
Dead plant along with black sclerotis.

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Management strategy
None

Sooty Blotch
Cymadothea trifolii

What to look for?
Not as common on red clover as it is on white and alsike species.

Photo: Howard

Picture description
Sooty spots on leaves.

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Management strategy
A 3 year rotation with nonlegumes.

Target Spot
Stemphylium sarcinaeforme

What to look for?
Similar to Stemphylium loti that occurs on birds-foot trefoil. Yield losses can be significant due to leaf drop prior to swathing.

Photo: Howard

Picture description
Distinct yellow lesions.

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Management strategy
Swath early to avoid excessive leaf drop.

Mosaic
Alfalfa Mosaic Virus

What to look for?
This virus can affect clovers, trefoil, as well as alfalfa. The virus is spread by several species of aphids. Old stands of clover like that of alfalfa, may be 100% infected. Most plants may be symptomless for this virus infection.

Photo: Howard

Picture description
Virus mosaic on clover leaf.

Photo: Howard

Picture description
Virus mosaic patterns.

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Management strategy
None

Vein Clearing
Vein Clear Virus (or Red Clover Vein Mosaic)

What to look for?
This virus may be fairly common on older stands of red clover. The virus is spread in a stylet-borne manner by several species of aphids.

Photo: Howard

Picture description
Sharp distinct virus mosaic along with vein clearing.

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Management strategy
None.

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

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 December 16, 2003.
Last Reviewed/Revised on March 18, 2008.