There is a good diagnostic field test for this disease. Cut a plant near the crown and squeeze sap from the newly cut stem. Heavily infected plants will ooze a milky sap from the cut stem. Regardless of whether you see the milky sap, touch a clean knife to the cut surface and draw the surfaces apart. If you see fine threads stringing from the stem and the knife blade, then the plant has bacterial wilt.
Bacterial wilt is carried by the cucumber beetle .
The bacteria hibernate in the digestive tract of the beetles. Feeding by these insects results in deep wounds to leaves. Bacteria enter these wounds and thereby the rest of the plant through insect feces. The bacteria multiply within the xylem vessels of the plant until water movement is obstructed. Symptoms normally appear 6 to 7 days after infection.