Dishing the Dirt: Common Plant Problems
By Jeff and Eileen Bidwell
Bugs ‘n’ slugs ‘n’ snails—oh, my! Summer is here at last; at least according to the calendar. This year’s cool days and chilly nights surely contradict our calendars, but after our long, wet winter, nothing keeps a true gardener out of the garden.
While nature beckons us, it also attracts uninvited visitors. If you’re out in the early morning surveying the results of your labor, you may find your garden resembling a battlefield. Stems have been chewed and broken, there are slimy trails leading in all directions, and what on earth is the foamy stuff? What is feasting on your rhodies? And what is causing those unsightly black spots on the leaves of your roses?
“What is happening to our garden?”, we may ask. Answer: see above—it’s nature.
Take comfort that you are not alone. At our weekly Plant Answer Clinic at the Ballard Sunday Farmers Market, we have been answering the same inquiries from many of our neighbors. Therefore, we decided to devote our June column to identifying and finding remedies for common summer problems.
A common question is about slugs, the prevalent Northwest nemesis that invade at night, leaving trails of slime in their wake. Several safe and relatively effective remedies, including Worry Free, Sluggo, and Escargo are available at local garden centers. Simply follow directions on the package. Copper barriers keep slugs from entering your garden. Abrasives such as crushed eggshells and coffee grinds can work by irritating their tender undersides. We’ve even heard of using coarse sandpaper. Apply these around each plant before it becomes a gourmet feast for the slimy critters. Our neighbor, a passionate slug hater, goes out late at night with flashlight in hand and plucks them one by one. If you choose this method, don’t forget the gloves.
The season also brings annual problems with roses. Most common among these is black spot, which appears on the leaves. A water borne fungus, it can be controlled by removing damaged leaves and flower buds, pruning dead wood, and raking all the leaves and twigs from beneath the plants. Avoid composting diseased plant material, as it may spread fungus spores to health plants. To prevent black spot, water your roses regularly from the soil, but avoid getting the leaves wet.
Powdery mildew, a white, powdery substance, affects a wide variety of ornamentals and edibles. Another fungus spread by spores, it attacks the leaves by coating them with a white, powdery substance. Since the fungus often attacks plants stressed by inconsistent water, it can be prevented by keeping your plants healthy through regular watering. Once again, it is best to remove affected areas when symptoms of the fungus first appear. Then apply an organic anti-fungal spray, which can be found at any garden center. Follow the directions carefully.
Night time brings another undesirable visitor that finds rhododendrons especially tasty. Root weevils are chewing insects whose presence can be identified by the little (and sometimes not so little) notches on the leaf borders and browning of the leaves. An easy way to rid your garden of these pesky pests is to place a white sheet under each plant, shake the leaves and watch them drop. If after hours gardening isn’t for you, sticky barriers like Tanglefoot or Stick-em will interrupt their journey to destruction. A biological way to control weevils is to introduce nematodes, beneficial insects who like the weevils as much as they like your rhodies.
Cutworms are dirty little devils awaiting mothdom. These caterpillars also arrive in the evening when the sun goes down (I see a theme here.) The larvae, brownish gray critters about ¼ to ½ inch long, are voracious destroyers that live in the soil and attack numerous garden plants. One deterrent is to spread a cup of shredded cardboard around the base of each plant, creating a barrier they won’t cross.
For after-dark gardening enthusiasts, perhaps the most satisfying remedy is to spray your plants with a mixture of insecticidal soap and water and watch them rise to the surface. Then apply a healthy amount of cornmeal, a cutworm favorite. In no time, your problem will be solved.
An early morning foray into your garden may include the sighting of little frothy white tufts everywhere. If you peer inside one of them, you will likely see a tiny inhabitant. Commonly known as spittlebugs, they also have a much cuter name—froghopper. Spittlebugs are not harmful to plants, but if the sight of them offends you, simply spray them with your hose and watch them disappear.
Our last intruder comes in shades of brown, green, red, black and yellow. Aphids have tiny, pear-shaped bodies with little tubes that pierce plans and suck juices, spreading viruses that yellowing and leaf curling, and depositing a sticky, black substance called honeydew.
Aphids reproduce rapidly, often leading to huge infestations, but remedies are simple and natural. Check under leaves regularly, and spray them with regular, strong blasts of water from your hose. Also effective is a mixture of two teaspoons of soft soap like Ivory dish liquid or Dr. Bronner’s Peppermint Soap in a spray bottle filled with water. This dehydrates them. Add a small amount of vegetable oil to clog their respiratory systems, and spray away. End of aphids. Sticky Traps available at Garden Centers are another effective means of aphid control.
By using Integrated Pest Management methods, you can safely rid your garden of common pests with minimal impact on the environment. For more information on safe products, order the free guide “Grow Smart, Grow Safe”, from the Washington Toxics Coalition, watoxics.org.
See you at the Market!
Jeff and Eileen Bidwell are King County Master Gardeners and long-time Ballard residents. You can find the Master Gardener Plant Answer Clinic at the Ballard Sunday Farmers Market every Sunday from 10 a.m. until 2 p.m., May 1st through September 25th.