Striped and spotted beetles bring bacterial wilt to cucumber plants

Every time I plant cucumbers, I hold my breath, because there's a good chance they'll perish before they produce.

Why? Unfortunately, oftentimes our cucumber plants become infected with bacterial wilt (Erwinia tracheiphila), a fatal disease imparted to cucumber plants by cucumber beetles when cucumber beetles bite the plants.

Early symptoms of bacterial wilt include cucumber plants that wilt, then temporarily regain their vigor at night after they've been watered. The plants quickly get progressively worse, however, before they perish.

Yet another way to tell that bacterial wilt has infected cucumber plants is to slice open a stem. If instead of finding clear fluid inside, the fluid is stringy and sticky, the plants have been infected.

Dealing with bacterial wilt

Years ago, a farmer suggested that I could mitigate my cucumber loses by starting them after the Fourth of July, because the beetles have mostly departed by then.

Which reminds me, cucumber transplants are typically hard to locate during this time of year, since most folks have already purchased them for spring plantings. Cucumber seeds, on the other hand, are easier to find, and at this time of year, cucumber seeds sprout in a few days and start fruiting in four to six weeks.

The striped cucumber beetle (Acalymma vittatum) and the spotted cucumber beetle (Diabrotica undecimpunctata) are the bugs that infect cucumber plants with bacterial wilt. But a good way to protect cucumber plants is to bug-proof them with store-bought floating row covers, sheet-like shields made from lightweight fabrics.

For cucumbers to form, though, their flowers must be pollinated. So when using protective covers, instead of permitting insects to get under the covers, I use Q-tips cotton swabs to spread pollen from flower-to-flower by hand. Then I immediately re-cover the plants.

Striped cucumber beetles are 1/4-inch long with three, black stripes running lengthwise down their green backs.

Spotted cucumber beetles are the same size, except they have 12 black spots on yellow-green backs.

This week in the garden

I saw the first Japanese beetle of the growing season, and I wasn't pleased. So that same day, I installed Japanese beetle traps and made certain I was well stocked with appropriate insecticides labeled for beetles and the plants in our landscape they prefer to feed on.

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