How to Identify Plant Pests and Diseases
By: Nancy Szerlag
Leaves are good indicators a plant is having problems. A curling leaf, a change in color, a few holes, a ragged edge or spots and splotches are often signs of trouble that if go unnoticed can quickly spread and disfigure or even kill a tree, shrub, rose or flower. But swift detection and action can ward off disaster and keep your garden healthy and happy.
Early morning is the best time to play detective in the garden. Many insects feed at night but are still around just after daybreak.
Leaves that look faded but upon close inspection are riddled with almost microscopic dots may be under attack from sucking insects. They usually hang out on the undersides of the leaves.
The fungal disease powdery mildew starts out with a few white spots on leaves and stems. The disease spreads rapidly and in a short period of time the plant is covered and looks like it has been in snowstorm. Quick action, that is spraying with a fungicide when there are a few spots will control the fungus and keep leaves of the plants clear. The disease moves quickly, so spraying immediately with milk at a rate of 1 part milk to 9 parts water is an effective “emergency home remedy” that has been used successfully by many until a fungicide can be purchased. Be sure to wet the undersides of the leaves and apply once or twice weekly.
Slugs chew holes in hosta but devour the leaves of many annuals and perennials, such as dianthus, petunias and marigolds. They feed at night and on overcast and rainy days. A slug hunt using a flashlight after dark is the best way to discover if these nasty little critters are chewing away in your garden. The best way to dispatch them is to drop the slimy bad guys in a cup of soapy water. Do wear rubber gloves for this job.
A magnifying glass is a simple and inexpensive tool (under $10) that’s perfect for sleuthing in the garden for early detection of insect and disease damage to the leaves of shrubs, trees, roses, flowers and grass. Also called a jeweler’s loupe, you can find them in craft stores, office supply outlets and online.
Diseased leaves that fall to the ground should be removed as soon as possible. The WORX TRIVAC blower/vac makes this cleanup easy. Simply blow the leaf litter from under the plants and then flip the switch to vacuum mode to pick them up. Empty the collection bag contents into garbage for disposal.
It’s key to identify the insect or disease to choose the right product to control it, so take cuttings of damaged leaves and stems along with any critters, in a plastic sandwich bag to your local garden center for an ID and recommendations on how best to treat the problem.