Garden Talk: June 17, 2010

From NGA Editors

Healthy Lawns and Healthy Lakes

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Runoff containing the nutrient phosphorus from fertilizer use is a big contributor to algal blooms and the resulting oxygen depletion in many lakes, rivers and streams. As a result, some states and communities have passed restrictions on the use of phosphorus-containing fertilizers. Minnesota, for example, now restricts their use on turf (but not agricultural or general garden use), with exceptions for soils that are shown to be deficient with a soil test, for the first year turf is being established and certain golf course uses.

Recently, scientists at the University of Minnesota conducted research on the impact phosphorus fertilization of home lawns has on water quality and turf quality. They confirmed that applying phosphorus to turf when a soil test shows there is no deficiency has no benefit to an established lawn. They did determine that there is a benefit to applying a phosphorus-containing fertilizer according to State Extension Service recommendations the first year following seeding or sodding and that, as long as recommended amounts weren't exceeded, water quality wasn't affected. They also found that, even if soil deficiency warranted applying phosphorus, late fall applications were of no benefit and were much more likely to run off into waterways.

One important finding from this research published in the Journal of Environmental Quality in 2010 was that, even if no phosphorus fertilizer was applied, the amount of phosphorus in the runoff increased as the vigor and quality of the grass declined. So keeping your lawn dense and healthy with appropriate lawn care practices helps not only your yard, but the environment as well.

For an abstract of this research go to Journal of Environmental Quality. For information on environmentally safe lawn care practices, go to Safe Lawns.

Bizarre, Incredible and Beautiful

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From pollen to seeds to fruits, you'll see the intricacies of plant reproduction in a whole new way as you peruse the fantastic photographic images in The Bizarre and Incredible World of Plants (Firefly Books, 2009). A compilation of the best of three earlier books, this volume is a visual feast of incredible, close-up photographs by visual artist Rob Kessler, who used special light and scanning electron microscopy to capture everything from an up-close view of the minute hairs covering the skin of a peach to the astounding array of shapes, sizes and structures of seeds and pollen.

These entrancing images are accompanied by interesting information from seed morphologist Wolfgang Stuppy and pollen expert Madeline Harley on the botanical purposes of plants' reproductive structures and the roles they play in preserving biodiversity. You'll find out about the many strategies plants have devised for getting their pollen and seeds where they need to go for the continuation of the species. For example, you'll learn that the largest seed in the world is carried by the nut of the Seychelles palm and that only 10% of plants are wind-pollinated. What a great way to increase your botanical knowledge!

For more information on The Bizarre and Incredible World of Plants, go to: Firefly Books .

The Best Veronicas

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There is an incredible variety of speedwells (Veronica) for a gardener to choose from, with new offerings from breeders every year. How to choose from among all this horticultural largesse? The Chicago Botanic Garden, located in USDA hardiness zone 5, recently released the results of a four to six year evaluation of 61 different species or cultivars of Veronica.

All plants were grown in full sun and well-drained clay-loam soil and were given minimal care in an effort to duplicate the treatment they'd get in most home gardens. The ratings were based on flower production, plant health, growth habit and winter hardiness. The judging was tough. Among the different species or cultivars evaluated, none earned the coveted 5 stars needed to be judged "excellent."

But quite a few received a 4-star "good" and 7 garnered 4½ stars. These latter included the hybrid 'Fairytale', with pale pink blossoms; hybrid 'Giles Van Hees', with darker pink flowers; V. austriaca 'Ionian Skies' with pale blue flowers; V. longifolia 'Blue John' with purple-blue blossoms; the V. spicata cultivars 'Baby Doll' with pink flowers and 'Ulster Blue Dwarf' with purple-blue; and V. wormskjoldii, also with purple-blue flowers. All of these plants have an upright growth habit.

The study also evaluated seven cultivars of the stately culver's root (Veronicastrum virginicum), with 'Apollo,' 'Fascination,' 'Lavendelturm' and 'Pink Glow' receiving "good" ratings.

For the complete report on Veronica, go to: Comparative Studies of Veronica and Veronicasturm.

Invasion of the Emerald Ash Borer

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The emerald ash borer is a beetle native to Asia that was accidentally introduced into the U.S. less than a decade ago. It is thought to have arrived in wooden packing materials brought in by ship or air. Since its discovery in this country in southern Michigan in 2002, it has cut a swath of destruction as it has steadily expanded its range. So far this damaging pest has killed tens of millions of ash trees in Michigan, Illinois, Indiana, Kentucky, Minnesota, Missouri, New York, Ohio, Ontario, Pennsylvania, Quebec, Virginia, West Virginia, and Wisconsin. Many more trees are at risk if this invader is not contained.

To help increase public awareness of the problem and provide information on identifying the borer and preventing its spread, fourteen states and two Canadian provinces have combined resources to set up a website that makes the latest information on the borer available to the public. It contains sections on borer identification, its current range, how to report infestations in your state, current research and what to do if you have an infested tree on your property.

The emerald ash borer only attacks ash trees (those in the genus Fraxinus). The adult beetle is bright metallic green and about ½-inch long. It lays its eggs on the trees' bark; it's the larvae that hatch out from these eggs that do the damage as they tunnel into the tree to feed under the bark, eventually emerging as adult beetles. Look for their D-shaped exit holes in the bark of infested ash trees. Another clue that a tree may harbor borers is heavy woodpecker damage, as these birds feed on the larvae inside the tree.

Perhaps the most important piece of information for the general public is the caution not to move firewood, as this is one way in which the borer can be introduced to uninfested areas. Many of the states that are currently fighting the borer enforce quarantines and fines to prevent potentially infested ash trees, logs or hardwood firewood from moving out of areas where the borer is found.

To visit this website for more information on the emerald ash borer, go to: Emerald Ash Borer.

 
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