Overcome these 4 nagging zucchini problems | TribLIVE.com
Jessica Walliser, Columnist

Overcome these 4 nagging zucchini problems

Jessica Walliser
Jessica Walliser | for the Tribune-Review
Squash vine borers are grub-like caterpillars that feed inside the stem of squash plants, causing plant death.

There’s a joke among gardeners who grow zucchini. During good years, we tease about leaving a few baseball bat-sized zucchini on the neighbor’s stoop and doing the old ding-dong-dash just to get rid of them. But, the truth is that it always seems to be feast or famine when it comes to zucchini. Either we’re up to our elbows in them, or the plants produce a few fruits and then die.

If you’ve had the latter experience a little too often, today I’d like to share some common challenges faced by zucchini growers and offer some tips for overcoming them. If you’re in the former group, with way more zucchini than you can handle, consider donating your extras to a local food pantry.

Here are some of the most common zucchini plant troubles gardeners face.

Poor pollination: If zucchini form on your plant, but they’re stunted on one end or they rot before they fully form, poor pollination could be to blame. Be sure to plant lots of flowering annuals and herbs in your vegetable garden to increase pollinator numbers. You can also use a paintbrush to move the pollen from male flowers (with a straight stem) to female flowers (with a bulbous stem) each morning.

Squash vine borers: This pest of all types of squash lays eggs at the base of the plant. The grub-like larvae then tunnel into the stems and eat the flesh, causing the plant to wilt and die. Wrap the bottom of the stems in a strip of aluminum foil to limit the female’s access to her prime egg-laying site. If you see sawdust-like material at the base of your plant, split the stem open lengthwise with a sharp knife, dig out the grub and squish it. Then wrap florists tape or a strip of plastic wrap around the cut portion to protect it.

Powdery mildew: This common fungal disease causes the leaves of zucchini plants to look like they’ve been dusted with talcum powder. Though it’s largely an aesthetic issue, sometimes powdery mildew can get so bad that it affects photosynthesis levels and causes leaf dieback. If this is the case, treat with an organic fungicide based on Bacillus subtilis, such as Serenade.

Squash bugs: One of the biggest woes faced by zucchini growers is squash bugs. If your plants produce well early in the season and then the leaves start turning crunchy and brown, look for these brown, shield-shaped insects. As nymphs, they’re gray and can often be found clustered in groups. Eggs look like small bronze footballs, found in groups typically on leaf undersides. Squash bugs are best controlled as eggs and nymphs. It’s challenging to manage them as adults. I go out to my garden every few days and use the sticky side of a piece of duct tape to collect the egg clusters and slow-moving nymphs, then I toss the tape into the trash.

There are also a handful of viruses and other pathogens that can affect zucchini plants, but none are exceedingly common here in Pennsylvania. Be sure to purchase new, certified virus-free seeds each year and give your plants a nutritious diet of compost and organic granular fertilizer at the start of every growing season. Healthy plants are less prone to diseases and less attractive to pests.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden,” “Good Bug, Bad Bug,” and her newest title, “Container Gardening Complete.” Her website is jessicawalliser.com. Send your gardening or landscaping questions to [email protected] or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.

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