By Melinda Myers
Every garden season is filled with beautiful and tasty surprises along with a few challenges. One challenge gardeners face each year is managing insect pests while keeping the pollinators safe. Fortunately, only a very small percent of insects in our landscapes are harmful. The rest help pollinate plants, feed upon or parasitize bad insects, or help decompose plant debris.
Proper identification of the plant-damaging culprit is the first step in managing problems. Often the insect that is most visible is not the one causing the damage. You can find lots of helpful information and images online. Look for websites hosted by your local University, extension service or botanical garden. They often provide timely tips on pests in your area.
Once identified, you will need to decide if control is needed. Some insect damage is just cosmetic meaning the plant’s health and longevity are not adversely affected it just looks bad. In these cases, control is for us not the health of our plants. Consider tolerating the damage and masking it with nearby plantings or garden art. In other cases, the damage is done, and the insect is no longer present. Revenge spraying may make you feel better but does nothing to fix the problem. Make a note on next year’s calendar to watch for and manage the pest if you feel control is really needed. Finding pest problems early makes hand removal easier and may be all that is needed.
Often when we see the damage on our plants, control will not help. Many galls, unusual growths on plants, are caused by insect feeding. When we see the gall, the insect is either safely living inside the gall or it has fled to complete another stage of its life. At that point, control will not work and in most cases, this is a cosmetic issue and control is not needed.
Work with nature to help manage pest problems. By tolerating some damage, you provide the food that attracts nature’s pest controllers to the garden. Watch for aphid eating lady beetles and green lacewings that eat hundreds of these pests each day. Invite songbirds to your landscape with seed and berry producing plants and a clean, fresh source of water. Ninety six percent of terrestrial birds feed their young insects. And then there are those non-stinging, parasitizing wasps that lay their eggs in other insects. When the eggs hatch the young feed on the host. Avoid pesticides and provide water and shelter to attract and support insect eating toads and frogs.
Enlist help from the youngsters in your life. Try the pluck, drop, and stomp method. Teach young gardeners to identify problem insects, pick them off the plants by hand, drop them to the ground and stomp. What a great way to teach kids about nature and help them burn off some of their excess energy.
Handpicking or knocking insects like Japanese beetles into a can of soapy water is a great way to manage small populations of pests. A fellow horticulturist uses a small hand vacuum to capture Japanese beetles. Just be sure to empty the insect filled vacuum contents into a can of soapy water before storing.
If you decide you need to lend nature a hand managing garden pests, look for more ecofriendly options. Barriers of floating row covers – fabrics that allow air, light, and water through – can keep cabbage worms, onion maggots, Japanese beetles, and some other insects from laying their eggs on their favorite plants. Cover the plants with the fabric at planting, anchor the edges and leave enough slack for plants to grow. No construction is needed.
Covering squash plants at planting until flowering begins can help reduce the risk of squash bugs and squash vine borers. Covering cucumbers at planting until ten days after flowering begins helps reduce the risk of cucumber beetles infecting these plants with the bacteria that causes wilt. The row covers also prevent birds from dining on the seeds and seedlings.
Cover late plantings of susceptible plants as needed this season. Then make a note on next year’s calendar to enlist this method for controlling these types of pests for your first planting next year.
Enlist the help of the naturally occurring soil bacteria Bacillus thuringiensis (Bt) to protect plants from certain pests. Different strains of this bacteria control different insects. Bt kurstaki only kills true caterpillars. Using this on members of the cabbage family won’t harm other butterflies since these plants only attract the cabbage worm moths. Bt galleriae will control Japanese and other beetles.
Use a strong blast of water to dislodge mites and aphids. These pests suck plant juices and secrete a clear sticky substance called honeydew. Extensive feeding can cause distorted growth, speckling, yellowing, and browning of the leaves.
If more control is needed, look for help from one of the organic contact insecticides like Summit Year-Round Spray Oil, a lightweight horticulture oil. These products kill the insects they contact but leave no residue on the plants that can harm beneficial insects that visit the plants later.
Whenever using any product, even natural and organic, be sure to read and follow label directions. This will ensure the best control and least negative impact on beneficial insects and the environment.
Take a few notes on pests you encounter, any management strategies used and the results. This will help when encountering problems in the future. With minimal time and a bit of creativity you can keep your garden looking good all season long.
Melinda Myers has written more than 20 gardening books, including the recently released Midwest Gardener’s Handbook, 2nd Edition and Small Space Gardening. She hosts The Great Courses “How to Grow Anything” DVD instant video series and the nationally syndicated Melinda’s Garden Moment TV & radio program. Myers is a columnist and contributing editor for Birds & Blooms magazine and her website is www.MelindaMyers.com.