The Wild and Wonderful August Garden

August 2, 2021 | C.L. Fornari | Plants

Holes, Hornworms, Weird Vegetables and Aphids

It’s August, and all kinds of interesting things are showing up in our gardens. From the weird to the wonderful, here are some of the things our customers are noticing in their gardens.

Holes in the Hardy Hibiscus! If your hardy hibiscus leaves are looking like lace, you’re seeing the damage done by the hibiscus sawfly larvae (Atomacera decepta). This green caterpillar is hard to spot since it usually feeds on the underside of the leaf and its color blends in with the plant. It is, however, easy to control. Spray the underside of your hardy hibiscus with spinosad, the active ingredient in Captain Jacks Deadbug Brew. Usually you only have to spray it once, but it’s good to note on your calendar to spray the hardy hibiscus in early July and you’ll avoid most damage in the coming years.

This is the damage done by the hibiscus sawfly larvae. You can still be effective with a spinosad treatment in early August.

Hornworm! They’re large, fat and simultaneously beautiful and creepy…plus they can strip the leaves off a tomato plant faster than a chipmunk can steal the ripening fruit. They are tomato hornworms, the larval form of a sphinx moth. If the tops of your tomato plants are suddenly being stripped, and you see what looks like coarsely-ground black pepper on the leaves below, you probably have a hornworm. Look carefully for this bright green larvae. Some people relocate these hungry, hungry caterpillars to one of the weeds in the nightshade family. Others smash them or feed them to the crows. But if you find one that is covered with what looks like white rice, leave it alone. The white attachments are the cocoons of pupating braconid wasps, a natural control of the hornworm.

Tomato hornworms are actually quite amazing. They only eat plants in Solanaceae family, so they can occasionally be found feeding on pepper or potato plants, as well as on nightshade weeds.

One of nature’s controls is the braconid wasp. Like something out of a horror movie, the female wasp lays her eggs inside the hornworm, and they eat their way out, forming cocoons of pupating wasps on the hornworm’s dying body. If you have many hornworms, be sure to till the garden soil in that area in the fall. This exposes the pupae of the hornworm to the winter weather, killing many.

Orange Aphids! If you have butterfly weed or milkweed in your gardens, it’s likely that you’ll see some of these plants covered with orange aphids. These are Aphis nerii, also called Asclipias or oleander aphids. They only occur on a few plants, so don’t worry that they will spread to all the flowers or shrubs in your landscape. If you want, you can spray them with insecticidal soap…or just ignore them and leave them for the predators that eat them.

These Asclepias aphids are as brightly colored as the flowers on this butterfly weed were when it was in bloom.

Weird and Wild! Many people find odd flowers, vegetables and plants in their gardens at this time of year. From strangely contorted stems or flowers to amusingly shaped vegetables and fruit, nature’s work is endlessly fascinating. Here are some examples.

This is an example of fasciation on an Echinacea flower. Fasciation can show up on stems (see photo below) or flowers. It happens when some of the plant cells multiply like crazy. This can be caused by several situations including hormonal imbalances, bacteria, insects, mites or fungi. Some plants show fasciated growth every year. Others have it once and never again, or die afterwards.

This Lespedeza plant in C.L. Fornari’s garden gets fasciated stems every year. They continue to grow wider and wider, sprouting many tiny leaves and flowers.

This is a photo of a fasciated lily posted on the Cape Cod Gardening Facebook group by Megan Lane. WOW! When a lily has a fasciated stem and many flowers like this, it’s typical for them not to come back the next year, so it’s great that Megan’s husband got photos!

Yellow summer squash frequently produce joined fruits. This isn’t fasciation, but results when two flowers (twins!) develop on the same stem.

From the weird to the wonderful, August is a good time to look closely at the plants in your garden. — Sometimes we harvest funny, sweet or just plain strangely shaped vegetables. This heart potato is one of the sweet ones!

Posted in Plants