The official advice is that if your impatiens melted and died abruptly last year, skip them for this growing season. Even if they didn’t, planting them will be a big risk as humid and moist conditions — read, the Washington summer — will promote the downy mildew in the months ahead.
Finding them might also be tough: The disease is so devastating that some nurseries are not selling them in 2013 and major growers have cut back impatiens production drastically.
This is a big deal in the flower trade. In the past 50 years impatiens have become one of the major bedding annuals by volume and dollar value as breeders figured out how to grow impatiens that were bushier and had more flower punch.
Homeowners and commercial landscapers developed a large appetite for them.
“It’s one of our most popular annuals, second for us only to petunias,” said Gary Mangum, whose company in Elkridge, Bell Nursery, supplies Home Depot retailers in much of the Mid-Atlantic. His growers have reduced impatiens production by more than 50 percent this spring.
Meadows Farms, a major garden center retailer with 22 locations in the region, announced it was not selling disease-prone impatiens this year. Usually, the plant represents 30 percent of its sales in annuals.
“People don’t understand the extent of the problem,” said Barry Perlow, a designer at Meadow Farms Landscaping in Chantilly. “By planting them now, they’ll be compounding the problem. The spores live for years.”
Actually, even if everyone were to stop growing impatiens — an unlikely scenario — a moratorium might do little to block the disease, said Margery Daughtrey, a plant pathologist at Cornell University, because its spores appear to survive on other host plants. One of them is the native jewelweed, that rangy, orange-flowered wildflower found along streambanks and noted for its coiled, explosive seed capsules.
Daughtrey said the golden age of the impatiens may be over.
“Long-term, I think we’ll see impatiens being a minor bedding plant instead of a major bedding plant,” she said. “This is something that has changed it from a plant with almost no diseases or insect problems to a plant with a real Achilles’ heel.”
The long-term solution might be for hybridizers to breed resistant strains but “we are a long way from getting resistant . . . varieties,” said Mary Ann Hansen, a plant pathologist at Virginia Tech. “We need to learn a different approach, not planting those large beds of a monoculture.”
The fungal disease, which surfaced in Europe a decade ago, showed up in commercial greenhouses in the United States soon after, but was controlled by fungicides unavailable to consumers. The disease appeared in gardens in New York in 2009 and by 2011 it was widespread, discovered in California, the Midwest, Florida and the Northeast. It hit our region last year.
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