Disease imperils future of bedding impatiens

Akron Beacon JournalMay 18, 2013 

LIFE MOONGARDEN LX

Bedding impatiens are susceptible to a disease called impatiens downy mildew that is fatal to the plant and easily spread by wind, water and infected soil.

FRANK ANDERSON — KRT

  • Alternatives to impatiens

    Here are other plants to consider for your garden's shady spots

    New Guinea impatiens

    Many gardeners are familiar with New Guinea impatiens (Impatiens hawkeri), which can tolerate a little more sun than bedding impatiens but still are good performers in shade. Their flowers are similar in appearance to their relatives' but bigger and not as profuse. They grow more upright than bedding impatiens, but they don't form masses of color the way bedding impatiens do. But they do come in a wide range of flower colors, and some varieties have leaves with interesting colors and patterns. Like bedding impatiens, they need a good amount of water.

    SunPatiens

    SunPatiens (Impatiens x hybrida hort 'SunPatiens'), a hybrid between New Guinea impatiens and wild impatiens, are even better suited for sun but also do well in partial shade. Heavy shade can make them leggy. SunPatiens are similar in appearance and growth habit to New Guinea impatiens. They need consistent moisture, but unlike bedding impatiens, they can tolerate high heat. They also hold up well to wind and rain, and don't need to be deadheaded. They can grow tall: 3 to 4 feet for the vigorous types, 2 to 3 feet for the compact ones, 2½ to more than 3 feet for spreading SunPatiens. So be aware that depending on the type you choose, you could end up with almost a flower hedge.

    Begonias

    Begonias are compact plants that can add a shot of color to a shady spot. One familiar type is wax begonias (Begonia x semperflorens-cultorum), bushy plants with waxy leaves and small white, pink or red flowers. They do best in partial shade. In deep shade they can get leggy and flower sparsely. Tuberous begonias (Begonia x tuberhybrida) come in a variety of colors and flower forms. They prefer shade most of the day, but their delicate flowers need protection from wind. Less familiar are dragon-wing begonias (Begonia x argenteoguttata 'Dragon Wings'), which have arching stems and showy, bell-shaped blooms in red or pink. They're often used in containers but can be planted in the landscape, too. All of these begonias like moist, well-drained soil and are deer-resistant. However, they're toxic to dogs and cats, the American Society for the Prevention of Cruelty to Animals says.

    Browallia

    Browallia (Browallia speciosa) can be grown in partial or full shade. Also called bush violet or amethyst flower, it got those names from its jewellike purple-blue flowers, which attract hummingbirds. It produces a rounded plant that grows 1 to 2 feet tall. Browallia needs well-drained soil, making it a good choice for drought-tolerant landscapes. It doesn't require much fuss. In fact, too much water or fertilizer will cause it to produce leaves instead of flowers.

    Coleus

    Coleus (Solenostemon scutellarioides) adds color to the garden not from its flowers but from its showy leaves. The colors and color combinations of its many hybrids are almost limitless. Coleus also comes in a variety of forms and sizes, from compact to lanky and from 6 inches to 3 feet tall. It prefers part shade but will tolerate full shade, and some newer cultivars can be grown in the sun. Although it's easy to grow, coleus looks better if it's pinched back regularly and its flowers are removed when they appear. It's toxic to dogs, cats and horses.

    Polka dot plant

    Like coleus, polka dot plant (Hypoestes phyllostachya) owes its beauty to its foliage. Plant breeders have created plants with green leaves that are dotted or splotched with pink, white or red. The deer-resistant plant will grow about 1 to 2 feet tall, and pinching will encourage it to stay bushy rather than get lanky. It likes part shade, medium moisture and well-drained soil, and does well in hot, humid weather.

    Torenia

    Torenia (Torenia fournieri) is also called wishbone flower because of the shape of its yellow stamens. Its small, velvety flowers look a little like pansies and come in white and shades of purple, blue, red and pink, and bicolor types. It's short, bushy plant that grows to about 6 to 12 inches. Torenia prefers part to full shade and needs plenty of water. It doesn't like hot, humid conditions.

    Vinca

    Vinca (Catharanthus roseus), or Madagascar periwinkle, is sometimes confused with impatiens because their flowers look so similar. Unlike impatiens, vinca will tolerate full sun and dry soil, although it also likes part shade. This easy-care annual grows about 1 to 2 feet tall. Flower colors are white, pink, red and shades of purple. The plant is deer-resistant but toxic to horses, cats and dogs. Don't confuse this vinca with Vinca minor, a groundcover periwinkle (also called myrtle) that can grow outside its bounds and into lawns or other areas where it's not wanted.

    AKRON BEACON JOURNAL

Gardeners can expect to find impatiens in short supply this year. A fast-spreading disease is threatening the flower, prompting some garden centers to cut back on supplies or not sell the plants.

The disease, called impatiens downy mildew, is caused by a funguslike organism. The disease stunts the plants' growth, causes the leaves to turn yellow and drop, and eventually causes the plants to collapse.

It was first seen on bedding impatiens in the United Kingdom in 2003 and in the United States in 2010. It was first reported in Kentucky last June in Franklin County.

The spores of the disease-causing organism are spread easily by wind or splashing water, and they live in the soil on infected plant debris — possibly for as long as five years, said Jim Chatfield, a horticulture educator with the Ohio State University Extension. That means impatiens could become infected from soil where diseased plants once grew, or from infected impatiens in a neighbor's yard.

Once a plant is infected, it can't be saved. A plant can be infected long before it shows any symptoms of the disease.

That troubles garden center owner Lisa Graf.

She said her family's business in Copley, Ohio, decided not to sell impatiens this year.

"It was a gut-wrenching decision," she said.

Impatiens are the top-selling annual flower in the United States.

She said the garden center considered offering the flowers and posting signs warning customers to plant at their own risk. But after long consideration, the operators decided they didn't want to set up their customers for failure.

Dayton Nurseries in Norton, Ohio, is cutting back on the quantity of impatiens it offers and pointing consumers to alternatives, but owner Tom Dayton said he's recommending the use of fungicide for those who insist on planting the popular annuals.

Gardeners must drench the impatiens with fungicide when they plant them and then reapply regularly, he said. That's why he's telling his customers to use the product only if they're committed to keeping up with the application schedule.

"If you are a hit-or-skip kind of person, you might as well not plant impatiens," he said.

Impatiens downy mildew affects primarily bedding impatiens, both single- and double-flowered types. It also affects native impatiens known as jewelweed, but the extent of the problem among those wildflowers isn't clear, Chatfield said.

The disease does not affect New Guinea impatiens or Sunpatiens or other types of plants such as cucumbers or basil. A number of plants are susceptible to diseases commonly called downy mildew, Chatfield said, but those diseases are different from the one infecting impatiens.

No one is sure what the future will hold for impatiens. Because the disease is fairly new to the United States, researchers are scrambling to find solutions.

Chatfield hopes that with good sanitation and management in greenhouses that grow the flowers, impatiens could rebound. But for the near term, at least, masses of impatiens blooms probably will become an uncommon sight.


Alternatives to impatiens

Here are other plants to consider for your garden's shady spots

New Guinea impatiens

Many gardeners are familiar with New Guinea impatiens (Impatiens hawkeri), which can tolerate a little more sun than bedding impatiens but still are good performers in shade. Their flowers are similar in appearance to their relatives' but bigger and not as profuse. They grow more upright than bedding impatiens, but they don't form masses of color the way bedding impatiens do. But they do come in a wide range of flower colors, and some varieties have leaves with interesting colors and patterns. Like bedding impatiens, they need a good amount of water.

SunPatiens

SunPatiens (Impatiens x hybrida hort 'SunPatiens'), a hybrid between New Guinea impatiens and wild impatiens, are even better suited for sun but also do well in partial shade. Heavy shade can make them leggy. SunPatiens are similar in appearance and growth habit to New Guinea impatiens. They need consistent moisture, but unlike bedding impatiens, they can tolerate high heat. They also hold up well to wind and rain, and don't need to be deadheaded. They can grow tall: 3 to 4 feet for the vigorous types, 2 to 3 feet for the compact ones, 2½ to more than 3 feet for spreading SunPatiens. So be aware that depending on the type you choose, you could end up with almost a flower hedge.

Begonias

Begonias are compact plants that can add a shot of color to a shady spot. One familiar type is wax begonias (Begonia x semperflorens-cultorum), bushy plants with waxy leaves and small white, pink or red flowers. They do best in partial shade. In deep shade they can get leggy and flower sparsely. Tuberous begonias (Begonia x tuberhybrida) come in a variety of colors and flower forms. They prefer shade most of the day, but their delicate flowers need protection from wind. Less familiar are dragon-wing begonias (Begonia x argenteoguttata 'Dragon Wings'), which have arching stems and showy, bell-shaped blooms in red or pink. They're often used in containers but can be planted in the landscape, too. All of these begonias like moist, well-drained soil and are deer-resistant. However, they're toxic to dogs and cats, the American Society for the Prevention of Cruelty to Animals says.

Browallia

Browallia (Browallia speciosa) can be grown in partial or full shade. Also called bush violet or amethyst flower, it got those names from its jewellike purple-blue flowers, which attract hummingbirds. It produces a rounded plant that grows 1 to 2 feet tall. Browallia needs well-drained soil, making it a good choice for drought-tolerant landscapes. It doesn't require much fuss. In fact, too much water or fertilizer will cause it to produce leaves instead of flowers.

Coleus

Coleus (Solenostemon scutellarioides) adds color to the garden not from its flowers but from its showy leaves. The colors and color combinations of its many hybrids are almost limitless. Coleus also comes in a variety of forms and sizes, from compact to lanky and from 6 inches to 3 feet tall. It prefers part shade but will tolerate full shade, and some newer cultivars can be grown in the sun. Although it's easy to grow, coleus looks better if it's pinched back regularly and its flowers are removed when they appear. It's toxic to dogs, cats and horses.

Polka dot plant

Like coleus, polka dot plant (Hypoestes phyllostachya) owes its beauty to its foliage. Plant breeders have created plants with green leaves that are dotted or splotched with pink, white or red. The deer-resistant plant will grow about 1 to 2 feet tall, and pinching will encourage it to stay bushy rather than get lanky. It likes part shade, medium moisture and well-drained soil, and does well in hot, humid weather.

Torenia

Torenia (Torenia fournieri) is also called wishbone flower because of the shape of its yellow stamens. Its small, velvety flowers look a little like pansies and come in white and shades of purple, blue, red and pink, and bicolor types. It's short, bushy plant that grows to about 6 to 12 inches. Torenia prefers part to full shade and needs plenty of water. It doesn't like hot, humid conditions.

Vinca

Vinca (Catharanthus roseus), or Madagascar periwinkle, is sometimes confused with impatiens because their flowers look so similar. Unlike impatiens, vinca will tolerate full sun and dry soil, although it also likes part shade. This easy-care annual grows about 1 to 2 feet tall. Flower colors are white, pink, red and shades of purple. The plant is deer-resistant but toxic to horses, cats and dogs. Don't confuse this vinca with Vinca minor, a groundcover periwinkle (also called myrtle) that can grow outside its bounds and into lawns or other areas where it's not wanted.

AKRON BEACON JOURNAL

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