Bacterial Wilt Of Cucumbers
If you’re wondering why your cucumber plants are wilting, you might want to look around for bugs. The bacterium that causes wilt in cucumber plants usually overwinters in the belly of a specific beetle: the striped cucumber beetle. In the spring, when the plants are fresh, the beetles awaken and start feeding on baby cucumber plants. This spreads the bacteria either by mouth or through their feces, which they leave on the plants.
Once the beetle starts chewing on the plant, the bacteria enter the plant and multiply very quickly in the plant’s vascular system. This starts producing blockages in the vascular system that causes cucumber wilt. Once the plant is infected, the beetles are even more attracted to the cucumber plants suffering from cucumber wilt.
Stopping Bacterial Cucumber Wilt
When you find your cucumber plants are wilting, investigate to see if you can find any of these beetles. The feeding isn’t always obvious on the leaves you can see. Sometimes, the wilt will show up on the cucumber by flagging on individual leaves. Sometimes it’s just one leaf, but it will quickly spread to the whole plant until you find several leaves on cucumber turning brown.
Once a plant has cucumber wilt, you’ll find the cucumber leaves wilt and the cucumber plants dying early. This is no good because you won’t yield any cucumbers on the infected plants. In order to prevent cucumber wilt, you need to know how to get rid of the beetles. Cucumbers that you harvest on cucumber plants dying early are usually not marketable.
One way to find out if you actually have bacterial cucumber wilt is to cut the stem and squeeze both ends. A sticky sap will ooze out of the cut. If you stick these ends back together and then pull them apart again, making a rope like connection between the two in the ooze, this means they have the bacteria. Unfortunately, once cucumbers have wilt there is no saving them. They will die.
When you find leaves on cucumber turning brown and your cucumber plants are wilting, control the bacterial wilt before it ruins your whole crop or next year’s crop. As soon as seedlings come out of the ground in the spring, you’ll want to start controlling the beetle. You can use products like Admire, Platinum or Sevin, which will provide you with control all growing season if applied frequently. Alternatively, you can use row cover cloth to keep the beetles off the plants so that they never have the chance to infect the plants.
Wilting Cucurbits: How to Identify Problems in the Field
Growing cucurbits can be really frustrating for homeowners. Often our melon, cucumber, and squash plants are doing great but then they wilt overnight!
The most common cause of wilting on melon and cucumber is the cucurbit bacterial wilt. This is a bacterial disease that’s transmitted by the striped and spotted cucumber beetles. The first symptoms of wilt are droopy leaves on a single vine or entire plant. This is easy to confuse with water or heat stress, except that infected plants do not recover and eventually die.
There’s an easy way to determine if your plants are wilting due to bacterial wilt. First, check that the wilting vine is still attached to the plant. If it is, use a pocket knife to cut the vine and very slowly pull the ends apart. If you see sticky strands or bacterial ooze, there’s a good chance this plant is infected with bacterial wilt. You can also cut the stem and touch one of the ends with the tip of your finger, slowly draw it away and observe if there is any strands are formed (see picture).
For more information view the Purdue University Pest Management Program video online.
Squash can also become infected with bacterial wilt. However, it’s easy to confuse this disease with squash vine borer damage. The squash vine borer is a wrinkled, white caterpillar that feeds inside squash plant stems (usually near the soil line) from June through August. If your zucchini or pumpkin wilted, first check the base of the plant and look for small holes and frass (insect poop). If you cut the stem in half, you might be able to find one or more caterpillars inside the stem. If no borer or borer damage is found, this plant might be infected with bacterial wilt.
Watermelons do not get infected with bacterial wilt or squash vine borer. If watermelons are wilting, this might indicate that there’s a fungal problem coming from the soil. Fusarium wilt of watermelon causes plants to wilt, and it may begin in one or more vines. Pull out a plant and look for any browning or discoloration at the base or on the roots. Using a sharp blade, cut the stem lengthwise and look for brown streaks on the inner tissues. Fusarium and other fungal infections typically cause browning of vascular tissues.
Bacterial ooze from wilt-infested plant.