| Cucumber bacterial wilt is caused by the bacterium,
Erwinia tracheiphila, and is characterized initially by
wilting and drying of individual leaves, especially
those exhibiting cucumber beetle injury. Cucumbers
and muskmelons are more susceptible than
pumpkins or squash; the disease is rarely a problem
on watermelons.
Symptoms and Diagnosis
Infected plants initially show wilting and drying of
individual leaves. As the leaves wilt and shrivel,
stems may dry out suddenly. Later, wilting spreads to
entire branches and vines. Wilting will occur during
the middle of the day during periods with high water
stress. The vine may recover at night. Eventually,
however, the entire vine will wither, collapse, and
die. In partially resistant plants, symptoms appear as
dwarfing, excessive blooms, and branching. A good
diagnostic test for this wilt is to cut a wilted stem
near the base. Touch a knife blade to the cut and
draw away from the cut. White to clear strings of the
bacterial ooze will be strung out from the cut made
on the infected plant to the knife blade. This
diagnostic test is not 100% reliable. Further
investigation may be necessary.
Life Cycle
The bacteria overwinter in the digestive system of
the cucumber beetle. In the spring, bacterial wilt is
spread from plant to plant through both the striped
and spotted cucumber beetles that feed on
cucumbers and other relatives of this family. The
bacteria are released through the insect excrement
and move into host plants through the stomates and
wounds, most likely the ones made when the insects
feed. Insects ingest more bacteria as they feed on
infected plants, and the cycle is repeated.
Integrated Pest Management Strategies
1. Protect plants with netting. Prevent cucumber
beetles from feeding and infecting plants by
covering them with netting or porous fabric.
2. Remove and destroy plant material when
symptoms of wilting are first noticed. There are no
cures for the disease. Beetles spread the
bacterium from infected plants to healthy plants.
3. Grow susceptible crops on rotation every third
year. Since beetles overwinter in the soil and
carry the bacterium, the cycle can be disrupted
by only planting the host in an area every
third year.
4. Avoid planting cucurbits next to corn. Spotted
cucumber larvae also feed on corn; avoiding
close plantings of these two crops may help
control the beetles on cucurbits.
5. Grow varieties that tolerate bacterial wilt like
butternut or acorn squash and Saladin or County
Fair 83 cucumbers. No muskmelon varieties are
known to be tolerant to bacterial wilt.
6. Dust plants with insecticide in the spring before
the cucumber beetles have a chance to lay eggs
(April-June). Apply pyrethrum, rotenone, or
carbaryl (Sevin). Try an insecticide-bait
combination such as Adios that has cucurbitacin,
the beetle attractant, and a small amount of
carbaryl (Sevin). | 
