For many gardeners, harvesting delicious zucchini is one of the highlights of the growing season. Therefore, zucchini growing problems are often frustrating. In this article, learn what to do about some of the most commonplace zucchini bugs that attack your precious plants.
If you feel intimidated by a seemingly long list of garden pests, don’t worry. There are numerous straightforward solutions to most zucchini plant problems. With a bit of planning in the spring and quick action when you spot an infestation, your zucchini harvest is safe.
Healthy plants are considerably more resilient against pest attacks, so providing them with appropriate amounts of light, nutrients, and water is their best defense.
Keeping your garden free from weeds and being thorough in your fall cleanup helps prevent insects from overwintering in the beds. Read on to discover the best ways to get rid of zucchini bugs before they damage your crops.
Best Remedies for Familiar Zucchini Plant Problems
Zucchini or Cucurbita pepo is a summer squash in the Cucurbitaceae plant family. It’s closely related to cucumbers, gourds, melons, and winter squash like acorn or butternut. Other examples of summer squash include crookneck, pattypan, and straightneck yellow squash. When to plant zucchini seeds is in the spring for a summer harvest.
Squash plants are easy to grow and usually recover from insect damage if the problem gets addressed quickly. Symptoms of plant distress from pest activity include curled or wilting leaves, yellow leaves on a zucchini plant, brown spots on the foliage, and diminished fruit production.
Before spraying pesticides, remember that these chemicals also impact beneficial insects like pollinators and predators. Zucchini plants rely on insects for pollination.
More often than not, predatory insects efficiently control pest populations. Use insecticides as a last resort, and implement cultural controls like companion planting, trap cropping, and floating row covers to deter pests.
North American Zucchini Bugs
As soon as you see signs of insect damage, it’s critical to act fast. If you spray for insects, use an organic, non-toxic product and target only the infested areas to avoid killing helpful bugs.
Insecticidal soap is effective against a wide variety of pests and doesn’t kill beneficial insects. In addition, it doesn’t leave behind harmful residue and is simple and inexpensive to make at home.
Pour the ingredients into a clean spray bottle. Spray all parts of the affected plants, including the undersides of the leaves where insects like to hide. The soap and oil smother the insects on contact during all phases of their life cycle, including eggs.
Aphids are one of the most prevalent garden pests and feed on plants by sucking the sap from leaves, making them curl and pucker. They’re tiny, about an eighth of an inch long, ranging from black, brown and green to pink, red, and yellow.
If you see fluffy white bugs on zucchini plants, they may be woolly aphids. Clusters of woolly aphids sometimes look like powdery mildew on zucchini leaves at first glance.
Sometimes all it takes is a strong blast of water from your garden hose to knock them off the plants. Treat a severe infestation with insecticidal soap or a DIY aphid killer spray, and plant aromatic herbs and flowers to attract natural predators like ladybugs, lacewings, and hoverflies.
What grows well with zucchini to deter bugs? Nasturtiums and sunflowers are effective trap crops. Plant them three to eight feet away from the zukes. An overabundance of nitrogen increases aphid reproduction. Avoid over-fertilizing, and always follow the instructions listed on the package.
There are two different cucumber beetles in North America: spotted (Diabrotica undecimpunctata howardi) and striped (Acalymma vittatum).
They both do the same damage to zucchini plants, and the pest control tactics are identical for both. The adults are bright yellow or orange with black markings. They lay orange-yellow eggs, and the larvae are white with a darker head.
Cucumber beetles feed on the stems and leaves of cucurbit plants. In addition, these insects often spread plant diseases like bacterial wilt. Nasturtium, radishes, and tansy repel cucumber beetles when planted nearby.
They overwinter in plant debris, brush piles, and other protected areas. The larvae feed on roots underground before emerging in late spring or early summer.
To eradicate a severe infestation, spray the plants weekly with neem oil. It’s a contact insecticide, so make sure to hit them directly. The scent also helps to repel cucumber beetles for a week or two. Spray in the evening when the insects are most active.
Squash Bugs (Anasa tristis)
Squash bugs appear dark gray or dark brown with a wide, flat body measuring about a half-inch long. Their feeding causes zucchini leaves to turn yellow or brown and wilt.
Squash bugs emerge in early spring to mate and usually lay eggs in June. The eggs are copper-colored and appear on the undersides of plants’ leaves where the veins meet to form a “V.”
If you see egg clusters on your plants, wipe them away with a gloved hand or crush them before the eggs hatch. Luckily, squash bugs only produce one generation per year.
Adult squash bugs are difficult to eradicate with pesticides, as they quickly escape while you’re spraying. If you have severe squash bug problems in your area, spray with an organic insecticide like spinosad or permethrin in early spring to kill the nymphs.
Plant bee balm, catnip, marigolds, and radishes near your zucchini plants to repel squash bugs, similar to cucumber pests and diseases and their remedies. The insects often shelter in debris at the base of the plant, so keep this area clear.
To trap squash bugs, place a piece of cardboard next to the plants overnight. In the early morning, gather and kill any squash bugs you find underneath.
Squash Vine Borers (Melittia cucurbitae)
After overwintering underground, adult squash vine borers emerge in late spring and lay eggs at the base of cucurbit plants. The eggs hatch a week later, and the larvae bore into the stems to feed. They remain active for several weeks before burrowing underground to pupate until next spring.
The adults are orange and black with metallic green wings, and their larvae are white and worm-like with a darker head. The copper-colored eggs appear around the base of the plant and sometimes on leaves and stems.
Squash vine borers are sometimes devastating to your zucchini crop. In 24-48 hours, the plants go from healthy to wilting and collapsing as the larvae bore into the stems.
If you notice that just one leaf or the end of a vine has gone limp, look for a borer’s entry point. If you see a small, dark hole, immediately remove that part of the plant before the rest becomes infested, too. Check the leaves and stems for eggs and crush them.
Neem oil, pyrethrin, and spinosad are useful organic insecticides for squash vine borers. Treat the plants in the morning or evening while pollinators are less active.
Another strategy for trapping adult vine borers is a bright yellow bowl full of soapy water. Since squash blossoms are yellow on most types of zucchini and other summer squashes, the color attracts the bugs.
Stink Bugs (Halyomorpha halys)
Stink bugs often get confused with squash bugs since they look similar. Their bodies are darker-colored, wider and rounder than squash bugs. They feed on the sap of leaves, which wilt and turn yellow or brown. Getting rid of stink bugs on tomatoes or squash can be challenging.
Unfortunately, stink bugs are resistant to most types of insecticides. Keep weeds under control, and hand-pick the insects off the plants when you spot them. Catnip, garlic, lavender, and thyme repel the insects with strong odors.
Stink bugs are attracted to shiny things. Make a DIY stink bug trap by filling an aluminum roasting pan with soapy water and placing it where you see the most insect activity.
Cultural Controls for Zucchini Growing Problems
Solving your zucchini plant problems shouldn’t involve spraying toxic chemicals on your plants. In addition to killing beneficial insects, these chemicals aren’t safe to use on food plants. Avoid products containing carbaryl or imidacloprid.
Diatomaceous earth is another natural insecticide, but it’s not ideal for use on zucchini plants when they’re flowering. It also kills pollinators that come in contact with the dust.
Numerous insect pests overwinter in the soil or nearby plant debris. Changing where you plant your veggies each year is helpful, a practice known as crop rotation. Cedar mulch also repels a variety of pests.
Squash bugs, vine borers, and cucumber beetles reportedly prefer Blue Hubbard squash to zucchini, making it a practical trap crop to keep the pests off your prized zucchini.
The trap plant should be about five feet away from the zucchini when they’re full-grown. This strategy works best if the Blue Hubbard plant is more mature than the zucchini, so plant it two weeks earlier.
Protecting the plants with row covers in the springtime is an excellent way to prevent insects from laying eggs on them. Remember to uncover the plants for at least an hour each day once they begin flowering to ensure pollination. Otherwise, hand-pollinate the blossoms.
Zucchini growing problems may seem discouraging at first, but there are plenty of options to eliminate zucchini bugs naturally. Use preventative measures like crop rotation and companion planting to help prevent severe infestations from occurring. Spray pesticides as a last resort, and be mindful that they affect beneficial insects, too.
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