By Susan Reimer, The Baltimore Sun
March 20, 2013
Impatience for spring is growing, but impatiens are not.
The nation's top-selling annual flower — favored for its last-frost-to-first-frost profusion of colorful blooms — has been struck by a killer mildew that can be carried by the wind and lingers in the soil.
"Impatiens have been a sure thing for years and years," said Cornell plant pathologist Margery Daughtrey. "Now they are risky."
Found in just about every state east of the Mississippi and with no cure, impatiens downy mildew, which hides on the underside of the plant's leaves, has put growers and retailers in a tough spot: Take the vulnerable plant and big-time seller off the shelves to protect the unsuspecting customer from a disappointing garden experience? Or risk the ire of the customer for whom impatiens is the go-to shade bedding plant?
Gardeners of every stripe, from rank beginners and time-strapped homeowners to seasoned veterans, count on impatiens to bring a shady spot to life.
Kathy Metro, who has been gardening in Hampstead for 25 years, had no idea mildew was the reason her impatiens looked so bad last summer. She pulled them out early, thinking there was something wrong with her soil.
"It is my favorite flower. I love the colors," said Metro, who bought more than 100 last year in orange, red, pink and white. "They have such a pretty showing."
This year, she will try something different to brighten her shade gardens, she said. "I could take a chance, but to spend all that money and then have them die off?"
Meanwhile, some growers are making the decision on their own, cutting back the number of impatiens they grow by as much as half, or cutting out the plant altogether.
"While impatiens generate significant revenue in the spring, we want our customers to be successful in their gardening efforts and do not feel we can sell impatiens in good conscience," said Jay Meadows, president of Meadows Farms Nurseries and Landscape, which has 22 outlets in the Baltimore region. Impatiens represent a quarter of his company's bedding plant sales.
"We hope other garden centers and nursery supply companies will refrain from the temptation to sell impatiens," he said. "We feel they are doing their customers an injustice by selling this product until this very serious disease is under control."
But the disease can survive the winter in the soil. It loves cool, wet spring weather, and wind can carry the spores 100 miles or more. Even if you did not see evidence of the disease during the last growing season, that doesn't mean you are safe this year, experts say. It is in 32 states, including Maryland, and the District of Columbia.
Area garden centers seem split on the matter. Behnke's in Beltsville won't carry impatiens and neither will Valley View Farms in Cockeysville. But Homestead Gardens in Davidsonville will. Big-box stores like Home Depot, Lowes and Walmart will still carry them.
"Even though the growers can treat the plants with fungicides," said Marian Parsley of Behnke's, "that only lasts for a window of time, and right now there is no remedy available to the home gardener."
"I have been going around to garden clubs spreading the word," said Carrie Engel of Valley View, which sold a quarter of a million dollars worth of impatiens last year. "There is almost a relief. They had the problem last year and now they know it wasn't their fault.
"After that, the gardeners are like, OK, what else have you got?"
The answer may be begonias, another colorful bloomer for the shade. Growers like Gary Mangum of Bell Nursery in Burtonsville are putting their money there and in New Guinea impatiens, a cousin of the common impatiens and mildew-resistant.
It isn't easy for a grower to turn on a dime, but he cut the number of impatiens by half and increased the number of begonias he is growing.
"It is difficult in one short year to go in a completely different direction," he said. "But we want the consumer to have a good experience."
Mike Leubecker of Tidal Creek Growers, which supplies Homestead Gardens, is planting about 40 percent fewer impatiens, but the plants will be there for the determined customer — along with signs and banners to educate gardeners.
"It is a risk either way," he said. "Not grow them and face a lot of demand. Grow them and people stay away."
A spokesman for Home Depot said that the company will carry impatiens in the same numbers as in the past and that sales associates have been trained to answer customers' questions.
George Ball of Burpee, which offers seeds and live plants via mail order, reports his greenhouses are disease-free.
Downy mildew, like so many plant diseases, is a puzzle. It has existed in the wild in the United States since the late 1800s and has never been seen in the production market. It first appeared in England in 2003, but there was no history of the disease in that country.
Did it cross over from the wild, or catch a ride from England?
"Nobody knows the answer to that," said Daughtrey of Cornell.
Downy mildew is limited to the Impatiens walleriana, the common garden impatiens, and will not spread to other plants.
The spores, which are closely related to a water-born algae, act as parasites, sapping the energy reserves of the plant. The first signs are slightly yellowing, curling leaves. The disease progresses quickly until the plant is nothing but bare, browning, leafless stems.
It began to show up in Florida in the fall of 2011. By the end of the last season, growers knew they were facing the tough choice of taking this plant — which represents more than $100 million in wholesale sales — off the market until a disease resistant cultivar can be bred or risking the ire of the unsuspecting gardener.
"In all my years as a gardener, a grower, seed salesman and retail garden center owner," said Ray Greenstreet of Greenstreet Gardens in Lothian, "I have never experienced such a devastating disease hit our industry so rapidly in basically one season."
Daughtrey said so little is known about the habits of this disease that it is possible weather plays a primary role in its spread, meaning that there can be good seasons and bad, depending on temperature and rainfall.
"It is sad," said Daughtrey, "because the crisis is now and we don't have anything to offer the gardener that makes it better. We don't have a Band-aid."
She works with a number of growers in New York, and some of them were on the fence this winter. But ultimately, she said, "they decided they couldn't produce a plant under false pretenses."
Landscapers have the chemicals at their disposal to perhaps keep their installations disease-free for the season. But those fungicides are not available to the home gardener and, in any case, it would cost far more to save a $1.25 plant than it is worth.
For the homeowner determined to purchase impatiens, it makes more sense to use it as a specimen in a planter or a hanging basket instead of as a carpet of color in a shady spot.
"We are talking to our customers about a new kind of drama in the garden," said Engel of Valley View, who admits that almost all the substitutes are more expensive than this colorful little bloomer, and some are not as carefree to grow.
"Maybe we were in a rut and this will chase us out of it," said Daughtrey. "But you have to respect how much effect this one little plant has on us."
Impatiens downy mildew
What to watch for
•Inspect the undersides of the leaves regularly for signs of disease. (Powdery mildew is a different pathogen and can be seen on the top of leaves.)
•At the first sign of the disease, the plants should be removed, roots and all, sealed in a plastic bag and carefully disposed of. There is no cure for downy mildew, and the progression of the disease can't be stopped.
•Never compost a diseased plant.
•Remove any impatiens plant material, including dropped leaves, from the garden.
•Do not attempt to plant impatiens in that spot again. Spores can live in the soil.
If not impatiens, what?
•There are a number of shade annuals that can bring color to the garden. Perhaps it is time to experiment with something new.
•Begonias, coleus, caladiums, heliotrope, sweet potato vine, lobelia, sweet alyssum, salvia, wishbone flower or oxalis are colorful substitutes. And New Guinea impatiens can do well in the shade, if they get sun during some part of the day. And this cousin to the garden impatiens is mildew-resistant.
Copyright © 2013, The Baltimore Sun