How to Manage Pests

UC Pest Management Guidelines

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The bleached and wilted foliage of the plant on the left are symptoms of Fusarium wilt, caused by Fusarium oxysporum f. sp. medicaginis.

Alfalfa

Fusarium Wilt

Pathogen: Fusarium oxysporum f. sp. medicaginis

(Reviewed 11/06, updated 11/06)

In this Guideline:

SYMPTOMS AND SIGNS

The first symptom of Fusarium wilt is wilting shoots. Bleaching of the leaf and stem color follows, and finally there may be a reddish tint to the foliage. In roots, dark reddish-brown streaks occur in the stele (the center part of the root that contains the vascular tissue). In advance stages, the entire stele may be discolored. The dark discoloration caused by Fusarium wilt is in contrast to the yellow-brown discoloration of bacterial wilt.

COMMENTS ON THE DISEASE

Fusarium wilt is favored by high soil temperatures and was significant in the past in California, but resistant cultivars have now made this disease an infrequent occurrence. For more information on resistant cultivars, see the current leaflet Winter Survival Fall Dormancy & Pest Resistance Ratings for Alfalfa Varieties (PDF) from the National Alfalfa Alliance Web site.

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Alfalfa
UC ANR Publication 3430

Diseases

R. M. Davis, Plant Pathology, UC Davis
C. A. Frate, UC Cooperative Extension, Tulare County

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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