Disease guide

Kluyveromyces marxianus var. marxianus

USA (Oregon and Washington)

Symptoms are similar to those caused by soft rot bacteria. Diseased bulbs develop a soft, watery rot that tends to be confined to either the inner or outer fleshy scales and does not readily spread from scale to scale. When squeezed, fluid may exude from the neck of bulbs. Often, a large part of a bulb shows water-soaking and soft rotting.

This fungus can survive in infected bulbs in cull piles or in onion field debris. It may be spread by fruit flies and other insects, and infection is thought to occur through wounds or natural openings in neck tissues. Temperatures between 20-30°C (68-85°F) favor development of this disease.