April 16, 2013

Impatiens Downy Mildew Found In Ohio

The devastating impatiens downy mildew disease has been found in Ohio for the 2013 growing season, according to a report from The Ohio State University Extension.  “In the last seven to ten days there have been several reports of impatiens downy mildew’s appearance in the Midwest; as of this time we have two reports from Ohio,” according to an article on the Ohio State University Extension website written by Francesca Peduto Hand and Nancy Taylor. “The pathogen that causes the disease, Plasmopara obducens, is extremely aggressive on bedding plant impatiens and Ohio’s impatiens producers should be aware of and scouting for this disease.” The article cites the early symptoms of impatiens downy mildew as a slight curling or mottling of the foliage, which may be subtle. High humidity, however, can result in a heavy coating of white sporulation on the underside of the leaves. “One grower described white dust floating above the […]

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December 3, 2012

Everything You Need To Know About Impatiens Downy Mildew

Editor’s Note: This article was written with the assistance of Ball Horticultural Company’s “Grower Guidelines” on Impatiens Downy Mildew and plant pathologist Dr. Colleen Warfield. For the most recent version of grower and retail guidelines, visit www.ballseed.com. Impatiens downy mildew is a destructive foliar disease of Impatiens walleriana that is capable of causing complete defoliation or plant collapse, especially in landscape plantings under moist conditions and cool nights. While there have been sporadic reports of impatiens downy mildew in U.S. greenhouses since 2004, it was not until the summer of 2011 that regional outbreaks of this disease were seen for the first time in landscape beds and container plantings in North America. In early January 2012, outbreaks of impatiens downy mildew were observed in landscape beds and greenhouses in south Florida. It is unclear whether this was a continuation of the 2011 outbreaks or a new cycle of disease for […]

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December 3, 2012

Growers Look To Limit Downy Mildew Losses

Downy mildew on Impatiens walleriana has been confirmed in more than 30 states, primarily in the eastern half of the United States. In 2012, the disease first started to be seen in Florida and then made appearances up the East Coast and in the Midwest during the spring and early summer. Landscapes in drier areas in the East were affected by the disease in late summer. Impatiens downy mildew also appeared in Texas, Washington, Oregon and the Gulf Coast states in 2012. “The disease was identified in only 13 states in 2011 and in 33 states in 2012,” says Margery Daughtrey, senior extension associate at Cornell University’s Long Island Horticultural Research and Extension Center in Riverhead, N.Y. “Even though a state was noted as having the disease, that doesn’t mean the entire state was affected. It means that a particular state had a case reported. It could have just been […]

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November 9, 2012

Kube-Pak’s Bill Swanekamp: Preparing For Downy Mildew In 2013

Impatiens downy mildew was one of the biggest disease stories of 2012, and the potential for more issues next spring has growers considering new ways to manage the situation. Impatiens walleriana is traditionally a big crop for Top 100 Grower Kube-Pak, in Allentown, N.J. Greenhouse Grower asked president Bill Swanekamp to talk about his plans for impatiens in 2013 and how he’s already working hard to protect his customers and his business this season. Greenhouse Grower: How was Kube-Pak impacted by downy mildew last year? Swanekamp: Even though there was downy mildew in our region, there wasn’t much of an impact on our 2011 season. We didn’t really hear about it from our customers because it showed up late in the summer. I think, in many cases, people assumed it was from the hot weather or the plants were just petering at the end of the season. Then, as we […]

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October 11, 2012

Downy Mildew On Impatiens: Resources And Advice

Impatiens Downy Mildew Found In OhioApril 16, 2013 | The Ohio State University Extension encourages growers to begin preventative treatment now. Everything You Need To Know About Impatiens Downy Mildew Dec. 6, 2012 | Ball Horticultural Company gives growers quick facts about the disease plaguing the country’s most popular bedding plant. How To Grow SunPatiens Dec. 6, 2012 | This disease-resistant alternative to Impatiens walleriana from Sakata Ornamentals gives consumers a comparable, colorful option for their gardens and landscapes. Growers Look To Limit Downy Mildew Losses Dec. 6, 2012 | Thirty-three states were affected by impatiens downy mildew in 2012. Growers are being proactive to limit financial and plant losses in 2013. Ball’s Mike Klopmeyer On What To Do In 2013 About Impatiens Downy MildewHow much of an affect will impatiens downy mildew have in 2013? Get an update on the spread of this disease and recommendations for your 2013 crops […]

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August 24, 2012

Impatiens Are Not Down And Out

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 […]

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July 14, 2012

Impatiens Downy Mildew Returns

Impatiens Downy Mildew, which began significantly impacting landscape plantings in 2011, is back again in 2012. Or possibly it never actually went away. Cornell’s Margery Daughtery and Ann Chase of Chase Consulting co-presented on recognition and management of Downy and Powdery Mildews Saturday at OFA Short Course, and Daughtery says the situation is already as widespread as last year, if not more so. “We have seen it on Long Island and in New Jersey, Pennsylvania, Ohio, Michigan, Indiana, Illinois, Virginia and other states as well, she says.  While it’s possible some of the disease was transported north from South Florida where there was a significant outbreak at the beginning of 2012, it’s also likely that some incidences are the results of infected plants in the landscape in 2011. There was concern about oospores produced in the stems of plants being carried over from year to year in landscape beds, and […]

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March 6, 2012

7 Tips For Protecting Impatiens From Downy Mildew

Last year’s outbreak of downy mildew in Europe virtually destroyed the crop and caused garden centers and mail-order catalogs to discontinue stocking it in favor of less problematic crops. A nationwide outbreak here in the United States is probably a stretch because regions experience vastly different environmental conditions. Still, downy mildew was spotted on impatiens on both coasts last year, so growers should be on high alert for the disease. “Impatiens grown in many areas of the United States may never be infected with downy mildew,” says Dr. Colleen Warfield, Plant Pathologist for Ball Horticultural Company. “Other areas may only see this disease sporadically. But if growers and landscapers are not aware of this disease and how to manage it, it certainly has the potential to develop into a far more devastating disease.” Speedling’s Mike Friddle, who was named Greenhouse Grower’s 2011 Head Grower of the Year, says he is […]

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February 21, 2012

Will Impatiens Sales Be Hurt By Downy Mildew This Spring?

Downy mildew alerts have been going out to growers around the country to make sure preventative measures are taken so the United States does not suffer the fate of Europe, where impatiens sales have dipped dramatically because of the disease. In 2011, downy mildew was a big enough problem that news headlines like: “Disease killing impatiens, Florida’s top landscape flower” in Florida and “Impatiens Running Out In Cape Cod” in Massachusetts, two of the areas hardest hit by the disease. Here are what two experts who have been following the disease here in the U.S. have to say: Margery Daughtry, Cornell University: Although Florida is having a terrible time with the disease right now, the Northeast and Midwest, etc., may see no problem this year if their plant supply chain is free from downy mildew. What I am waiting to find out this growing season is whether gardens that had […]

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February 7, 2012

Your Impatiens Might Have Downy Mildew If …

Growers across the country are scrambling for solutions, with the discovery of downy mildew on impatiens in the U.S. landscape. Look for these symptoms in the greenhouse when you’re scouting your impatiens crop this year: • Plant foliage that’s yellowish or pale green in color • Leaves that curl downward • Leaves that are distorted • Undersides of leaves that have white or light gray fuzz present • New and emerging leaves that are small and a discolored yellow or pale green • Flower buds that fail to form • Stunted plant growth If you see one or more of these symptoms on a plant, immediately seal it in a plastic bag before removing it from the greenhouse. Get it to a diagnostic lab for further testing. Additionally, when spraying for downy mildew, there are three important things to remember when applying fungicides: 1. Apply fungicides preventatively. 2. Rotate among […]

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October 11, 2011

How To Overcome Downy Mildew Spread On Impatiens

The town of Saratoga, N.Y., has observed downy mildew on Impatiens walleriana in public and private gardens for about three years. So it was only a matter of time, Margery Daughtrey thought, before downy mildew arrived about 250 miles southeast in Riverhead, N.Y. Downy mildew on impatiens officially arrived late this summer, around mid-September, when leaf yellowing and leaf drop on impatiens occurred, as well as the appearance of white spores on the undersides of leaves. Three weeks after those symptoms, stems collapsed onto the ground while nearby flower beds were still flowering and looking healthy. “They look very strange in this ‘stems-only’ stage,” says Daughtrey, senior extension associate at Cornell University. “We haven’t had any frost so this is purely a matter of downy mildew and conducive weather conditions.” Daughtrey describes the Northeast’s weather late summer as cooler than usual and constantly rainy. Those conditions helped spread the disease. […]

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