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Most gardens in the Sacramento area and beyond are without impatiens this summer because of a nationwide infection of mildew that quickly kills the plants. The mildew had been rare in this area.

Seeds: Uncommon mildew leaves Sacramento beds without impatiens

Published: Saturday, Jul. 6, 2013 - 12:00 am | Page 5CALIFORNIA LIFE

Notice anything different this summer? There are fewer impatiens.

Nicknamed "Busy Lizzies," these familiar flowers fill shady areas with blasts of bright colors. They rank among the best-selling annuals in America.

But a nationwide infection has killed millions of impatiens.

"Impatiens definitely had a lot of problems this spring," said Zak Norlyn of Redwood Barn Nursery in Davis. "We saw so many mildew problems, we stopped bringing them in. We won't sell something that would just die out there."

Downy mildew – rarely seen in Sacramento – is blamed for their demise. Downy mildew needs cool weather and damp air to take hold. That's something plants may experience along the California coast, where many impatiens are grown for distribution elsewhere, but not inland during Sacramento's summer.

However, Plasmopara obducens, the mold blamed for the impatiens crisis, doesn't behave like other mildews. And it only seems to attack one kind of plant: Impatiens walleriana.

New Guinea impatiens (Impatiens x hawkeri), a hybrid cousin, is not affected by the disease.

Plasmopara has been reported in 33 states including California. Resting spores are produced inside stems and released into the soil, where they infect other plants. Active spores (from the bottom of leaves) can be spread by wind or water.

In impatiens, this mold causes leaves to become mottled, yellow and fall off. Plants decay so quickly, the mildew's distinctive white fuzziness on the underside of leaves often fails to appear.

Entire beds can become infected and die within a week. The mold can remain a threat in the soil for a decade.

That's bad news. As a favorite bedding plant, impatiens are often planted in the same place year after year.

Cindy Nalepa-Nelson of Land Park bought impatiens the first week of April. She planted them in the same site she's used for 10 years.

"They started to lose leaves," she said. "They became very leggy and then they wilted like a winter freeze."

Nalepa-Nelson's plants weren't the only victims.

"I have seen other impatiens in my neighborhood with the same problem," she said.

No cure has been found for these sick impatiens. Gardeners are advised to destroy any sick plants and avoid planting more impatiens in the same place.

Because of so many problems with impatiens nationwide, several local nurseries stopped stocking them. They encouraged gardeners to try something else.

"Bedding impatiens are out, as far as I'm concerned," said Don Shor, owner of the Redwood Barn Nursery. "Downy mildew doesn't affect the New Guinea impatiens, nor is it a problem on fibrous begonias, so we still have options (including) all the new, cool coleus on the market and lots of great perennials for the shade."

Weather roller coaster

Plasmopara can be blamed for impatiens failure, but what about other plants?

"Ninety percent of all plant problems are water- related," said Sacramento radio host and lifetime master gardener "Farmer Fred" Hoffman. "It's operator error."

Recent wild fluctuations in temperature – 72 degrees one day, 106 degrees a few days later – stress plants as well as people.

"I think it will really affect (plants) down the line," Hoffman said. "Blossom-end rot will pick up big time."

Uneven watering – for example, allowing a plant to dry out completely, then overwatering – can lead to blossom-end rot, which causes damage to tomatoes, peppers and eggplants.

Hoffman recommended paying extra attention to irrigation.

"A boom-and-bust cycle can cause a lot of plant problems," he said. "You can't just set (irrigation) timers and walk away for the season. You've got to pay attention."

This summer's heat seems almost normal.

"Compared to last year's weird weather, 2013 is great," Shor said. "But the very dry north winds in April definitely stressed new plantings, especially with the lack of rain. Now, cool to blazing hot in one week is going to have some effects.

"My biggest concern is people overwatering, leading to crown rot and killing plants," Shor said. "Water thoroughly, and then check the soil before you water again! A plant will droop on a hot day – just like we will – even if it has adequate water. The soil should be your guide."

Call The Bee's Debbie Arrington, (916) 321-1075. Follow her on Twitter @debarrington.

© Copyright The Sacramento Bee. All rights reserved.

Read more articles by Debbie Arrington



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