Year before last, I had so many cucumbers I didn’t know what to do with them. I collected baskets and baskets and made dozens of jars of relish, pickles, and jelly. Just kidding, I didn’t make cucumber jelly.
But I was tempted.
Then last year, I blithely planted cucumbers again without a worry in the world, and sat back and waited for the deluge of cucurbits.
I noticed these little yellow and black striped beetles, but I didn’t notice any damage to the vines. They didn’t seem to be eating much, so I waved it off. The vines were growing and making little cukes, so I figured it was business as usual.
Then . . . the leaves started to yellow, the plants began to flag. Production was way off. The vines began to wilt and die. There were TONS of those little striped beetles I had ignored. I went into research mode, and whadya know: I had bacterial wilt disease (Erwinia tracheiphila), or rather, my cucumber plants had bacterial wilt disease. A disease transmitted by the piercing-sucking mischief of little yellow and black striped beetles, which have a name, by the way: Striped Cucumber Beetles.
There are striped cucumber beetles and spotted cucumber beetles. There are differences between the two.
Striped Cucumber Beetle
- Strong preference for cucurbits such as cucumbers, squash, and melons
- Lays eggs at the base of the plants and the larvae feed on the roots of the cucumber plant
Spotted Cucumber Beetle
- Feeds on over 200 different species of plant, not just cucurbits
- Lays eggs on grasses and does not damage cucurbit roots
- More often found further south than the striped cucumber beetle
They can damage leaves and blossoms and the fruit itself, but to me the most significant threat is bacterial wilt disease. The damage to the cucumbers themselves was minimal, but killing the whole plant is where it got serious for me.
This year, I planted cucumbers again, in spite of the threat. This time, I’m taking the SCB threat much more seriously. I’m doing a few things that are recommended for the organic control of this pest:
- straw mulch–slows beetle movement, provides a haven for spiders and other beneficials, & feeds decomposers that act as food for the beneficials
- hand picking–ever day I set a quota and try to squish as many as I can
- succession planting–I’ve planted three separate crops at different times so if one crop fails maybe I’ll get a second chance
- growing in lots of organic matter–thought to boost the plant’s internal defenses
- organic fertilization regime–homemade compost/comfrey tea–strong plants have better defenses
I tried using yellow cups coated with Tanglefoot and baited with clove oil but they failed to catch a single beetle. I contemplated using a vacuum, but the bother and the noise and the likelihood I would catch (and certainly annoy the stew out of) beneficials has stopped me from trying that.
There are, of course, organic-approved sprays, etc., but those still carry with them some danger of harming beneficials. Over time, organic conditions, what Eliot Coleman calls “Deep Organic,” lead to a balance of beneficials and pests and such healthy soil that pest and disease issues subside. Every time I bring out the sprays and dusts, however organic-approved, I get the feeling I’m setting back a natural balance a few steps.
Other controls that are suggested include row covers until blooms appear, trap crops on the perimeter of the garden, and planting resistant varieties.
At the present, things are looking much better than last year, and time will tell whether or not I need those second crops of cukes and whether or not they make it.
A note on hand picking cucumber beetles: They are very shy and sensitive to movement. You have to be very fast and think like a predator. When disturbed they usually let go of their footing and drop straight down. Either be too fast and stealthy for them or anticipate the drop and have a hand underneath to catch them. They also simply fly off. The best time I have found to catch them is early in the morning, especially after a rain, when I tend to find them in pairs (two for one squish).