Published on 01/28/98

Give Spring Plants Health Check Before You Buy

Georgia gardeners are itching to get to the best young plants at the nursery. To get the best, give them a thorough examination before you buy, say University of Georgia experts.

"The most important thing is to check the roots," said Paul Thomas, an extension horticulturist with the UGA College of Agricultural and Environmental Sciences. "You want to see fuzzy hairs on the ends of all the roots."

You can't judge roots by the color. Some plants, like azaleas, have naturally tan roots when they're healthy. Most perennials have healthy white roots. But fuzzy root hairs almost always mean the plant is healthy.

"Orchids are the exception," Thomas said. "They don't have root hairs."

The best way to check the roots is to gently slip the pot off the plant. If it doesn't slide off easily, it's probably root-bound. Choose another plant, or plan to repot it.

"If the root ball looks good, you can usually just put the plant in a pot that's one inch bigger all around," Thomas said. "Use fresh soil when replanting, to cut down on disease."

If the plant is root-bound, you can still work with it.

"Remove the bottom quarter-inch and the top quarter-inch of the root ball with your fingers," he said. "Then take a clean pocketknife and make several incisions on opposite sides the length of the root ball. These will allow roots to expand once repotted."

You can open and tease the roots out, but Thomas doesn't recommend pulling the root ball apart. "Most plants have delicate roots," he said. "Too many broken roots can be fatal. Work carefully and slowly."

After you check the roots for a healthy life-support system, check for diseases and insects.

The most common pest problems in young nursery plants include whiteflies and aphids, said Beverly Sparks, a UGA extension entomologist.

"To avoid problems, inspect the plants closely for all stages of the insect," Sparks said. "The immature stages of whiteflies are found on the underside of leaves. They often go unnoticed until the adults emerge and fly around plants."

Aphids are small and can go unnoticed until the population is large and the plant's new growth curls, twists or dies back. "With heavy populations," Sparks said, "you may also notice an accumulation of honeydew, a sticky secretion."

If you don't find the pest until you get home, the case may be terminal.

"Most of these type problems take persistence, time and knowledge of the pest biology and control options to eliminate the pest," Sparks said. "It's often more effective to replace infested plants than to fight the battle."

Diseases can be even more complicated to detect and diagnose. Some that are easier to spot are:

Fungal leaf spots. Fungi cause these. Usually, spots are round to irregular with a tan to grey center and a dark border (brown or purple). They're found most often during wet springs and falls.

Powdery mildew. Look for white to grayish, powdery spots on the leaf or stem. They may cover the entire leaf. Powdery mildew occurs most often in spring and fall when nights are cool.

Rust. Look for orange to rust-colored pustules on the leaf underside.

"Avoid plants showing these symptoms," said Jean Woodward, a UGA plant pathologist. "Don't buy a plant with leaf spots or blights, because you will bring the disease into your yard and battle it always."

You can't "cure" it, she said.

"Don't buy plants that look off-color or weak, either. They probably have a root rot disease," she said.

"Healthy roots are really the key to healthy plants," Thomas said. "You can revive most plants with healthy roots by applying fertilizer and then sitting it in a sunny window."

Faith Peppers is the director of public affairs with the University of Georgia College of Agricultural and Environmental Sciences.