Garden Talk: July 26, 2012

From NGA Editors

Mildew Resistant Ninebark

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Varieties of eastern ninebark (Physocarpus opulifolius), an eastern U.S. native shrub, have become popular landscape plants in recent years, beginning with the development of the cultivar Diabolo® (P.o. 'Monlo'). This now widely available cultivar was bred by German nurseryman Gunter Kordes from a chance purple-leaved seedling. Since then, other purple and yellow leaved cultivars have come onto the market. Gardeners appreciate these plants for their sturdy constitutions and cold hardiness.

But ninebark and some of its cultivars have an Achilles heel -- a susceptibility to powdery mildew, a fungal disease that coats the leaves with white and causes witches' brooms, sections of stems with distorted growth and discolored leaves, to form. To assess which cultivars were most susceptible to this problem, researchers at the University of Connecticut carried out long-term evaluations of a number of varieties.

Among the purple-leaved cultivars evaluated, the researchers found that Summer Wine® (P.o.'Seward'), a 4-6 foot tall and wide shrub with deep reddish-purple leaves, was the most mildew-resistant and was the only cultivar in the study that didn't show any signs of infection. Diabolo® (pictured) also performed reasonably well, with only moderate infection and minimal brooming.

Yellow-foliaged cultivars of ninebark are not as popular as the purple-leaved selections, since most don't retain their yellow color well as the season progresses. The yellow cultivar that showed the greatest mildew resistance was 'Luteus', a large, older cultivar that shows poor color retention.

A number of new dwarf ninebark cultivars have just been released, including the purple-leaved Little Devil™, Burgundy Candy®, and Caramel Candy®, and the yellow-leaved Lemon Candy®. Continuing evaluation as these new varieties are planted in landscapes will be needed to determine how well they resist infection by this troublesome fungal disease.

For more information ninebark and powdery mildew, go to: American Nurseryman.

All-American Daylilies

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Daylilies are popular perennials for their ease of care and the astounding variety of sizes, flower forms, and colors they offer. But selecting the best varieties from among this abundance can be a daunting prospect for some. That's where the All-American Daylilies test program can help.

Begun in 1987, this program uses a scientific methodology to evaluate daylilies based on 52 characteristics to identify the best varieties from among more than 40,000 cultivars. Since the first winner, 'Black-eyed Stella', was announced in 1994, 18 more cultivars have made the cut. Plants are tested at sites ranging from Zone 10 in Florida and California to Zone 2 in Alberta, Canada and are evaluated for quality and length of bloom, as well as strong foliage performance.

The most recent winner is 'Lady Elizabeth', with 5 inch, near-white flowers with a yellow eye carried on 18-24 inch high scapes above a mound of bright green, arching, deciduous foliage. Showing good rust resistance, 'Lady Elizabeth' is equally stunning as an accent plant or in a mass planting. Recommended for USDA Zones 4-10, it blooms in early to midsummer.

For more on 'Lady Elizabeth' and other winning daylilies, go to: All-American Daylilies.

Cheyenne Spirit Coneflower

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If you just can't make up your mind which of the many colors of coneflowers to grow, grow them all! Echinacea 'Cheyenne Spirit', just announced as a 2013 All-America Selections (AAS) Flower Award winner, produces a gorgeous mix of sunset hues, from rich purple, pink, red and orange to yellow, cream, and white. Flowers are borne on sturdy, well-branched plants that stand up to wind and rain and have few insect or disease problems. They are also drought-tolerant, making them a great choice for folks interested in sustainable, low-water use garden practices.

Bred by Kieft Seed, this Zone 4 perennial blooms the first year from seed if sown no later than January 25. Seeds should be sown on the surface or just barely covered with germinating mix. With bottom heat, they germinate in 10-15 days and are ready for transplant to larger containers in about three to four weeks.

An excellent plant for a butterfly garden, 'Cheyenne Spirit' makes a colorful addition to a perennial garden, is stunning as a mass planting, and makes a great cut flower. Capture the beauty of a Plains sunset in your garden from midsummer through fall with this award-winning new variety.

To read more about Echinacea 'Cheyenne Spirit', go to: AAS.

Award-Winning Rose

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Rose lovers across the country will be excited to learn that All-America Rose Selections® (AARS) has just announced its winner for 2013. Francis Meilland™ (Rosa 'Meitroni') is a tall, vigorous, very upright hybrid tea with large, white blooms suffused with a pink center and a strong, citrusy fragrance.

It also shows good disease resistance and is the first hybrid tea selected for AARS honors under no-spray conditions. AARS members voted recently to stop spraying all test roses with fungicides as a way to ensure that all future winners will perform well without the use of these chemicals. Roses are evaluated over two years in ten gardens across the country for disease resistance, flower production, color, and fragrance.

Introduced by Conard-Pyle Company, Francis Meilland™ will be available to consumers in the spring of 2013.

To find out more about Francis Meilland™ rose, go to: Conard-Pyle.

 
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