Home gardeners are busy harvesting their crops until the summer garden pests move in! To talk to an expert, I called up UK Extension Entomologist Dr. Jonathan Larson to see what information he could provide to keep these summer pests under control.
A popular summer pest in the Kentucky garden is the Japanese beetle. Japanese beetles are easily recognized by their attractive, shiny emerald-green and copper color. They are about 7/16 of an inch long, and if you look closely, you’ll see patches of white hair on their sides.
The beetles have sharp, chewing mouth parts that allow them to grind up tender leaf tissue between the veins, leaving the leaves skeletonized and lacy. But they don’t stop at leaves. They will shred flowers – you’ve probably seen them buried into the blooms on your roses – and even eat fruit. They attack and feed on more than 300 different plant species. Their favorites include linden, roses, grapes, blackberries and peaches.
So how do you protect your garden from Japanese beetles? First, if you’re in the process of planning or planting your landscape, consider including species and cultivars they don’t like to eat. Examples of those are most oaks, hollies, tulip trees and silver maples.
For those of us whose landscapes are mature and planting more trees isn’t feasible, one of the best methods is to simply pick off and kill beetles when you see them on your plants. Beetles will be strongly attracted to a plant that is already damaged by beetles. The more damage, the more beetles, resulting in more damage and more beetles. It’s a vicious cycle. If you walk through your garden in the evening and remove beetles by hand, you’ll cut back on the number of beetles that show up the next day. Pick them off and plop them in a bucket of soapy water.
There are insecticides available that can help kill or repel beetles, but always follow the label instructions carefully and beware of treating any plant that is blooming. Organic options, which offer a three to four days of protection, include Neem oil, pyola and BtG (Bt for beetles). Synthetic options, which offer protection for one to three weeks, include bifenthryn, carbaryl, cyfluthrin and lamda-cyhalothrin.
Another common summer garden pest is the squash vine borer. The squash vine borer is a key pest of squash, gourds, and pumpkins in Kentucky. Symptoms appear in mid-summer when a long runner or an entire plant wilts suddenly. Infested vines usually die beyond the point of attack. Sawdust-like frass near the base of the plant is the best evidence of squash vine borer activity. Careful examination will uncover yellow-brown excrement pushed out through holes in the side of the stem at the point of wilting. If the stem is split open, one to several borers are usually present. The caterpillars reach a length of 1 inch and has a brown head and a cream-colored body.
Monitor plants weekly from mid-June through August for initial signs of the borer’s frass at entrance holes in the stems. Very early signs of larval feeding indicate that other eggs will be hatching soon.
Home gardeners may have some success with deworming the vines. At the first signs of the sawdust-like frass, vines are slit lengthwise near where the damage is found and the borers removed. The stems should be immediately covered with earth. Sanitation is also important. After harvest is complete, vines should be removed from the garden and composted to prevent the remaining borers from completing larval development.
Gardeners should also be concerned with ticks that can harm the body. To hear the full interview with Dr. Larson, make sure to check out Episode 9 on Summer Garden Pests from the Sunshine Gardening Podcast!
We appreciate Dr. Jonathan Larson being our guest on the show! If you would like to learn more about insects, Dr. Larson also has his very own podcast called Arthro-Pod. To hear more about what is covered on the Arthro-Pod, click here: http://arthro-pod.blogspot.com/.
As always, gardeners keep on digging into gardening and remember to add a little sunshine!
Kristin G. Hildabrand, Warren County Extension Agent for Horticulture