University of Illinois Extension

University of Illinois Extension

Hort Answers

Bacterial Disease

Bacterial Wilt of Cucurbits
Erwinia tracheiphila

Bacterial wilt "silk thread"
Bacterial wilt "silk thread"
3 (1 = rare 5 = annual)
5 (1 = very little damage 5 = plants killed)
Bacterial wilt, caused by the bacterium Erwinia tracheiphila, is a serious threat to melon and cucumber production nationwide. It is less of a threat to squash and pumpkin crops and is uncommon among other cucurbits.

Plants Affected
Symptoms vary with the crop. Individual runners or whole cucumber or melon plants wilt and die rapidly. Wilt symptoms may appear at any growth stage but are most often noticed early in the season while the plants are growing rapidly. Affected runners first appear dark green and then wilt and die. An easy way to diagnose bacterial wilt is to sever a runner close to the crown, rejoin the cut surfaces for a moment, and then slowly pull them apart again. If the bacterial wilt pathogen is present, you will notice sticky strands connecting the cut surfaces as they are pulled apart.

Life Cycle
The pathogen is spread by contaminated striped and spotted cucumber beetles as they feed on plants. The bacterium is not seedborne, and there is no evidence that it survives in the soil.


Control of striped and spotted cucumber beetlevectors.

Related Resources
Home, Yard & Garden Pest Guide
U of IL - Distance Diagnosis through Digital Imaging
U of IL - Plant Clinic