This question was submitted by Diane. Researched and answered by Advanced Master Gardener Bruce.
What is your question for a Master Gardener?
I transplanted a cucumber plant from a big box store and it looked beautiful for several weeks. Lots of both male and female blossoms, large leaves (no apparent sign of bugs), and plenty of new growth. However, about once a week, all the leaves of one strand will suddenly wilt; the next day, the leaves are withered and dry, and in 1-2 more days, all the blossoms on that strand are completely dead. The rest of the plant looks fine. I originally tried using a solution of Dawn soap and peppermint oil, thinking it was bugs, but that didn’t seem to work (maybe I wasn’t spraying often enough?) I’ve stopped spraying since I’m not sure it was helping. I only have this one cucumber plant; it’s in a raised bed garden with one plant each of Cantelope, Watermelon, and Butternut Squash plants. The other plants look fine (other than I planted them later than I should have, so I might not get any fruit until very late in the fall). Any suggestions/thoughts on my dying cucumber plant? At this rate, I won’t have any cucumbers this year!
Thanks Diane for contacting us with your wilting cucumber vine question. Usually the main cause of wilt in cucumbers is bacterial cucumber wilt which is caused by an infected cucumber beetle. There is no cure for bacterial cucumber wilt. The plant needs to be pulled and destroyed. However, the second picture you sent may show another option for the cause of the problem. Enlarge the bottom horizontal stem and you will see an opening in the cucumber vine. I think you may have a squash borer that prefers cucumbers to squash. To save your plant there are two methods to correct the problem. Take a wire and insert it into the hole and run it up the vine to kill the grub that is eating its way through the interior of the vine. The other option is using an insecticide containing either bifenthrin, pyrethrin, neem oil, or carbaryl. Direct the spray in the hole so it can reach the grub. If you use a spray, follow the directions on the bottle for harvesting information. If you have several stems, inspect all of them for the borer damage. If possible cover the hole in the vine with some dirt or mulch. This should solve your dilemma. Please let us know the outcome or if you have other questions. Also check your butternut squash and watermelon for borer damage.