As August approaches and you look at your yard and garden, you can evaluate your successes as well as your disappointments. As you look at the successes, give yourself a pat on the back. Make notes so you can repeat or build upon them next year.
As for disappointments, don’t be too hard on yourself and don’t waste sleepless nights trying to figure out what you did wrong. Gardening can be a process of trial and error. The success of the last growing season doesn’t always carry over to the next season.
This is because growing conditions change from year to year. They also change from month to month. Just think of what happened this summer. In Cincinnati, June was the second driest month in 153 years of record-keeping. We only measured 0.08 inches of rain in June.
In July, over 120 millimeters of rain was recorded at the airport. Other areas received significantly more rain, as the rains were mainly caused by fast-moving storms. Towards the end of June, we were all talking about a summer drought that never came. The July rains were just what we needed. Plants that were stressed in June recovered well in July.
Most of the challenges in horticulture are behind us. Most of the insects of concern have come and gone. The only exception is the box tree moth. If you have never heard of this insect, it is very concerning.
This insect is not a problem as a moth. The larval stage, when the moth is a caterpillar, is the problem. These caterpillars eat the foliage and defoliate a box tree. This damage is unique to these insects. Box trees have been infected by other insects and diseases. Only the box tree moth caterpillars defoliate the plants. These insects can produce up to five generations per season; they reproduce quickly.
They are controllable. There are safe, environmentally friendly insecticides that work well against these insects. These would be products that contain an insecticide called spinosad. Another option that is also safe and environmentally friendly is a product that contains BT, Bacillus thuringiensis. These products can control these caterpillars and other insects if they are present on the plant.
You cannot and should not spray an insecticide to prevent these insects. You must regularly monitor your box trees for possible damage. If you notice damage, look for active insects. That is when you should spray.
Caterpillars are tricky insects. We find dozens of different species in our gardens. Many of the good insects spend their time as caterpillars, including butterflies. For this reason, we must be very careful when using even the safest insecticides.
Counties in southwest Ohio are under quarantine for this insect, meaning that boxwoods, whether alive or dead, cannot be moved outside of the designated counties. If you suspect you have an infestation of this insect, you should report it to the Ohio Department of Agriculture on their website agri.ohio.gov.
For as long as I have been in this business, which is to say, for most of my life, box trees have been considered to be largely insect-free. That has changed in the last 10 years. The most worrying insect is the box tree moth, as it can cause significant damage in a short period of time.
In situations like this, I like to remain optimistic. If we all work together to keep these insects under control, maybe one day the threat will disappear. I’ve seen this happen to a few others in the past.
