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Managing Summer Pests and Planning for Fall

Dark iridescent beetles are on a leaf they have eaten large chunks out of.
Peggy recommends manually removing Japanese beetles by knocking them into soapy water. (Photo: Peggy Singlemann)

Summer is in full swing with white panicles of Pee Gee and Limelight Hydrangea paniculata flowers complimenting the colorful Crape Myrtle, Lagerstroemia sp., blossoms making for beautiful displays throughout our communities. Vegetables and herbs are being harvested and enjoyed, shared, or stored for future use. Summer annual bedding plants are thriving with some requiring the pruning of their spent blossoms to encourage more to enjoy.

These past weeks, I have lost the battle with Japanese Beetles, despite knocking them twice daily into soapy water. This invasive non-native pest gained the advantage while I was on vacation, during which they skeletonized the leaves on my newly-planted dwarf fruit trees, a Rose of Sharon, and even a large Elephant Ear leaf! By mid-August, they should be back underground feeding on roots in their grub or larvae stage. To offset the leaf loss, I applied half-strength fertilizer to all affected plants after a recent rain. Removing the handful of immature apples further reduced the stress of each young fruit tree. Remember, I am looking forward to years of apples, so losing the crop this year is an investment in plant vigor, not a loss.

At Maymont, we recently removed a diseased Coneflower, Echinacea purpurea, that had Aster Yellows. This systemic disease distorts plant growth of infected plants while their flowers typically remain green. It affects those in the Aster Family and thirty-eight other families of plants. The disease is transmitted by the aster leafhopper insect, Macrosteles fascifrons.

On a positive note, mid to late summer is when Rhododendrons (Azaleas) and Camellias are setting their flower buds for next year. For optimum spring bloom, avoid pruning the plants until after they bloom and keep them well mulched to conserve soil moisture.

With this wonderful season of regular rain showers, the weeds seem to appear overnight. Annual crabgrass, Digitaria sp., is my biggest challenge along with Bermuda grass.

Crabgrass is native to Eurasia and is an annual plant that grows and sets seed from spring until frost. One plant can set over 150,000 seeds in one season! With that in mind, I put time into pulling these invasive plants while they are still young.

Bermuda grass, Cynodon dactylon, is native to Africa but grows worldwide. This vining grass thrives in the summer going dormant during the winter. The deep-rooted grass is a challenge to control. First, dig up as much of the roots as possible then smother garden areas for months with thickly layered organic matter and if necessary, resort to herbicides to kill the plant down to the roots. Trench edge garden beds to prevent stolons and rhizomes of this aggressive plant from creeping into a border from the lawn. Persistence is the key to control, no matter what method you choose to use.

A daily walk through the garden is important during the summer months to spy and address any insect or disease issues early on. With the frequent rain, it is important to follow your fertilizer program to keep plants producing flowers or vegetables, or sustaining their green growth. Early August is the last time to prune shrubs that do not bloom in the spring. Pruning will initiate new growth, which then needs time to mature and become hardwood to avoid damage by the first frosts of October.

Yes, fall is coming, which means it is time to begin sowing leafy fall vegetables and plan for fall planting projects! We recently completed a home project of installing raised beds that are three feet high, and at four feet wide, the beds are easy to tend. There is a planting plan, so later in August I will start to sow fall vegetables in my new raised-bed garden.

Thanks for watching Virginia Home Grown and remember, Gardening is for Everyone!

- Peggy,  Director of Park Operations and Horticulture of Maymont Foundation