Are your impatiens looking terrible this year – maybe even dying? A new disease, first identified in 2004, has been spreading rapidly across the United States and other countries and has now landed in Southern California. The disease is called Downy Mildew, or among scientists Plasmopara obduscens.

The disease is causing at least a mild panic among many home gardeners and professional landscapers. But before serious panic sets in, it is important to know that Downey Mildew only effects old-fashioned, regular impatiens. It has no effect on New Guinea impatiens or any other plant in the garden.

The disease is a pathogen, similar to a fungus, and it is deadly. Even worse, it is extremely difficult to diagnose and there is no effective treatment once it shows up in your garden.

Downey Mildew ravaged most portions of the East coast and Midwest last summer. Nurseries there were receiving reports of plants defoliating and then dyeing. At first, the culprits were thought to be poor watering habits, snails and slugs or even fertilizer burn. But soon, it was clear that Downey Mildew was the cause. This year, most garden centers in these areas have already discontinued the plant. The garden centers that continued to sell impatiens are doing so with a “plant at your own risk” approach. In Europe, where the disease got an earlier start, impatiens have been essentially eliminated impatiens as an option. Virtually no impatiens were planted in Europe this year. The U.S. may be headed for the same destiny.

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In Southern California a few widely scattered reports came in last summer, but nothing too serious and local researchers and garden centers were hopeful that the disease would not proliferate in our dry Mediterranean climate. We were wrong. During the past 30 days, reports have been flying in of dyeing plants. The plants look fine one day and then suddenly, often in only a few days, defoliate. Just bare stems are left. A few days later and the entire plant is withered and collapsed.

Downy-Mildew-img2Disneyland just announced that it has dropped impatiens from all of its facilities. The Biltmore Hotel, famous for its huge displays of pink and white

impatiens has also dropped the plant.

New Guinea impatiens and their hybrids are not affected by the disease.

Downy Mildew isn’t exactly a fungus, it is a water mold, but for the home gardener that’s a subtle distinction. It spreads from plant to plant in either of two methods; through water that stays on the foliage for a period of time or by spores that float through the air. Once it shows up, which we think is inevitable, there’s not much you can do about stopping it.

As the leading garden center in Southern California, on July 5th Roger’s Gardens made a difficult decision. We stopped selling regular impatiens, both in our store and in our landscape division, and removed them from our sales tables. We even removed impatiens from our planted baskets and bowls. It was a painful decision, but it was the responsible thing to do. Roger’s Gardens also announced that they would replace or refund any customer who has plants infected with the disease.

So far as we know, we are the first garden center in the area to notify homeowners and gardeners of the problem and to discontinue the plant. Impatiens are the number one selling plant at Roger’s Gardens as well as most other garden retailers. But rather than sell or promote a plant that will likely fail, Roger’s Gardens has chosen to offer better alternatives. I am proud of Roger’s Gardens for putting its customer’s success ahead of a short-term business interest. We hope other retailers and landscape companies will follow our lead.

Roger’s Gardens has discovered that nearly every wholesale impatiens grower in Southern California is infected with the disease. In fact, infected impatiens have been shipped and sold throughout Southern California, and probably continue to be. Buyer Beware!

So what should you do? That’s a very easy question. First, fly the white flag. Rather than roll the dice and take your chances; stop planting regular impatiens. It’s a bad gamble. If you already have impatiens in the garden we’re not recommending that you remove them; enjoy them while you can, but be prepared for problems.

Secondly, plant an alternative. Remember, other plants are not affected by this disease. Perhaps the most popular solution would be to switch to any of the New Guinea types of impatiens, including the popular series called ‘Fanfare’, Sun Harmony’ or ‘SunPatiens’. These will provide the closest appearance to a regular impatiens. In fact, these types of impatiens will even tolerate more direct sunlight than regular impatiens and have larger flowers and more handsome foliage. Lots of other choices abound as well, especially bedding begonias, which have been around for ages and are nearly as popular as impatiens. For the more adventuresome, other seasonal alternatives are coleus, campanula, mimulus, hypoestes, bacopa, dwarf fuchsias, torenia, cyclamen, cineraria, lobelia and several others.

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Impatiens have had a good run, but it’s time to move on.

By Ron Vanderhoff, Roger’s Gardens | July 18, 2013