Impatiens Are Not Down And Out
Despite disease pressure from Impatiens Downy Mildew, this genus is not down and out. Vigilance, prevention and education will be key to future success.
August 24, 2012
Impatiens — it’s not only a plant genus; these days, it’s a state of mind. With confirmed reports of Impatiens Downy Mildew in more than 20 states as of July 31 and disease pressure in 2013 expected to be worse, the industry is beginning to understand just how serious this issue could be for producers who grow one of the most popular bedding plants in America.
“Impatiens avoidance behavior will largely be seen for the first time in 2013,” says Cornell University Plant Pathologist Margery Daughtrey. “More outbreaks are occurring all the time that will continue to affect customer demand next spring. The amount of inoculum available in the trade and in the garden beds will interact with the spring weather patterns to determine what will happen next year — and those are all unknowns.”
But it’s not all bad news. Growers who preventatively treated for Impatiens Downy Mildew and followed strategies for keeping Impatiens walleriana crops separate from New Guinea Impatiens and other crops this past spring didn’t have an issue with the disease, Daughtrey says.
“Rather, problems developed after plants went to retail or into the landscape, where they were commingled with other species and the wind could inoculate plants from infected plants in
Let’s Work Together On Solutions
This still presents a challenge in educating consumers about Impatiens Downy Mildew. No one wants to get disenchanted with flowering annuals if impatiens fail in their affected landscapes. Impatiens are a staple for many gardeners because they are inexpensive and thrive in shade and part sun, covering large areas in wide swaths of color. In areas affected with Impatiens Downy Mildew, the industry needs to work together to promote the wide range of shade alternatives, Daughtrey says.
Ball Horticultural Co. and Syngenta have worked cooperatively to this end. At this summer’s OFA Short Course, Ball released a brochure, “Fresh & Stunning Shade Solutions,” to help growers promote alternative shade solutions to retailers, landscapers and consumers. The company also provides “Guidelines For Growers” on its company websites, which offers a comprehensive update on impatiens downy mildew, its background, hosts, symptoms, how it spreads, and cultural and chemical control guidelines.
Syngenta Technical Services provides growers with disease prevention protocol,which has been successful in helping them avoid contracting Impatiens Downy Mildew in the greenhouse.
Daughtrey and pathologists for Ball, Syngenta and BASF, among others, have been monitoring disease pressure across the country, trialing fungicides on affected plants and providing best practices for disease control.
Though there is currently “no silver bullet,” to eradicate impatiens downy mildew, the industry’s continued vigilance can go a long way to keep impatiens a mainstay in American gardens for the long-term, says Mike Murgiano, senior marketing manager at Syngenta Flowers.
“Following a preventative program in the greenhouse is essential,” Murgiano says. “Further industry collaboration to educate about this disease and steps that can be taken to slow its spread and mitigate some of its negative impact once established is imperative to ensuring industry and consumer success.”
Breeding New Alternatives
While breeders are collaborating to educate the industry and public about Impatiens Downy Mildew, they are also working individually to improve impatiens species genetically, culturally and aesthetically.
Ball Horticultural Co. Without getting too specific, representatives from Ball indicated that the company is still invested in developing new varieties of both Impatiens walleriana and Impatiens hawkerii (New Guinea impatiens).
“New innovations, as well as impatiens production efficiencies to help make growers’ lives easier, are part of our breeding objectives,” says Lisa Lacy, global product manager with PanAmerican Seed. Lacy says the Impreza series of traditional-type impatiens from PanAmerican Seed, introduced in 2011, has a superior plant structure that provides a longer shelf life. With better horizontal growth, less upward stretch and good soil coverage, it minimizes plant growth regulator use, and maximizes sales potential.
PanAmerican Seed’s Terry Howe, global product manager, says growers should watch for a further expansion of colors and patterns in its New Guinea impatiens Divine series, the industry’s only seed-propagated series.
“We anticipate an increase in interest for this variety, and an expanded flower color range will help broaden its use in landscapes and home gardens,” Howe says. She suggests that growers consider promoting New Guinea impatiens as a replacement for Impatiens walleriana in the landscape for the time being, while using Impatiens walleriana exclusively in containers.
“It’s time to bring New Guinea impatiens out of baskets and into the landscape,” Howe says. “Growers can benefit from economical seed inputs of New Guinea types, like the Divine series, and place them in packs for larger, mass plantings in the landscape. New Guinea impatiens are highly resistant to Impatiens Downy Mildew and offer a broad color range that will appeal to landscape designers and home gardeners.”
Ball also offers vegetatively propagated options with its Celebration and Celebrette New Guinea impatiens series from Ball FloraPlant, and decorative types like Patchwork, Fiesta and Fiesta Olé Fanfare trailing impatiens and Fusion exotic series to provide color in containers. Ball also markets Selecta’s Impatiens hawkerii ‘ColorPower Dark Pink Flame’ and Burpee Home Gardens Center Stage Impatiens.
Syngenta Flowers. Murgiano says while Syngenta is aggressively pursuing genetic solutions to Impatiens Downy Mildew, it doesn’t happen overnight.
“At Syngenta, we see many opportunities to leverage our deep understanding of genetics, chemistry and plant culture to begin offering some short-term solutions,” he says. “Combining the best genetics with plant protection products and specific growing protocols could offer consumers extended performance in the garden, even when disease pressure is present.”
Syngenta is also focusing on novelty items that help drive retail and consumer demand, like its Tumbler impatiens series, new this year.
“We drew inspiration for our Tumbler impatiens series from the many different forms that impatiens species take in the wild,” he says. “Tumbler is a seed impatiens that displays a true spreading, trailing habit, making it ideal for premium baskets, mixed containers and garden settings.”
Container gardening is an important trend for growers to help avoid the “one-size-fits-all approach” when it comes to impatiens, Murgiano says.
“Rather than using pack impatiens for all container types and sizes, look to the many different varieties available to create a premium look,” he says. “Our Tumbler series offers a real opportunity for an underserved segment. Its trailing habit allows consumers to see the colors they love at eye level, not just on top of their baskets. Likewise, large-flowered, mid-vigor impatiens like the Accent Premium series were bred specifically to create high-impact color in larger patio containers.”
Syngenta offers a range of downy mildew-resistant alternatives as well, including its GoldFisch range of Sonic and Super Sonic New Guinea impatiens, Murgiano says.
Sakata Seed America. With proven resistance to downy mildew in impatiens trials across Europe in recent years, Sakata’s SunPatiens impatiens are gaining ground in the industry as viable and vigorous alternatives. The hybrid series has tough foliage and a strong growth habit that is unaffected by downy mildew, says Marketing Manager Mark Seguin. In addition to their mildew resistance, SunPatiens have been a hit in the U.S. in the last few years because of their ability to flourish in extreme summer conditions, like many areas of the United States experienced this year.
Though growers have argued that a premium product like SunPatiens is cost-prohibitive to replacing lower-priced seed impatiens, Sakata offers a different perspective. Sequin says because SunPatiens are fast growers and provide excellent coverage, fewer plants are needed per square foot than seed impatiens.
“In addition to their proven disease resistance, SunPatiens provide many worthwhile economical benefits,” Seguin says. “Their ability to stand up against Downy Mildew gives growers and consumers another compelling reason to choose SunPatiens.”
Laura Drotleff is a freelance writer based in Willowick, Ohio. She spent seven-plus years as an editor on Greenhouse Grower. Reach Drotleff at firstname.lastname@example.org.