Garden Talk: July 21, 2005

From NGA Editors

New Improved Shrub

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The Texas Superstar Plant Program at Texas A & M University takes well-known plants and develops unique selections with new characteristics. In 2005 breeders improved upon a common landscape shrub in the South; the chaste tree (Vitex agnus-castus).

Long grown in USDA hardiness zones 6 through 8 as a landscape shrub, the chaste tree grows 15 to 25 feet high and wide and produces spikes of white, pink, or lilac-colored flowers.

The new improvement from the Texas Superstars Program involves the flowers. New varieties have larger, more colorful, and more fragrant flowers than old varieties. The varieties 'Montrose Purple', 'Le Compte', and 'Shoal Creek' all will be sold as 'Texas Lilac Vitex'. The blossoms are attractive in the landscape, make for beautiful cut flowers, and are appealing to butterflies.

To stimulate new flowers and prevent Vitex from self-sowing rampantly, cut back the shrub dramatically after flowering. Since the shrub flowers on new growth, new blooms will appear again in 6 weeks.

For more information on the ‘Texas Lilac Vitex’, go to the: Texas Superstars Program Web site.

New Corn Earworm Control

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Corn earworm is a big problem for gardeners across the country. An old-fashioned yet effective organic control is to apply a several drops of mineral oil on the corn silks (where the adult moths lay their eggs). As the eggs hatch, the oil smothers the emerging larvae, which would otherwise eat their way to the tip of the ear to feast on kernels. When combined with Bacillus thuriengensis (B.t.), the oil is even more effective, but the mixture can be difficult to apply with a regular dropper.

Now researchers at the University of Massachusetts and Hampshire College have developed a tool that makes applying the pesticide easier. Zea-Later consists of an ergonomic hand-held applicator connected by a clear plastic tube to a 2-liter tank that you can attach to your belt. The handle is molded to fit your hand comfortably. When you pull the "trigger" to release a dose of oil and B.t., you use all your fingers together thus reducing hand fatigue. To apply the pesticide, place the pointed tip at the center of the ear and push it slightly into the ear tip. Squirt the oil so it reaches into the ear tip. One tankful treats about one-quarter acre of corn. The best time to apply oil is 4 to 6 days after silk begins to grow, or 2 to 4 days after the silk is full-grown.

For more information on Zea-Later go to the University of Massachusetts Web site .

Clay Controls Weeds

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Over the past decade, kaolin clay was introduced as a disease and insect control for various crops (see "High Tech Dust Foils Pests"). Now, new research from the USDA suggests that this clay can be used to prevent weed growth as well.

In trials at the Agricultural Research Service lab in Kearneysville, West Virginia, researchers grew blackberries on soils treated with kaolin clay and those without the treatment. In one plot they mixed clay with soil at rates of 3 percent and 10 percent by volume. This created a kaolin clay “mulch” 1 to 2 inches thick. In another plot they sprayed a mixture of liquid kaolin clay directly on the soil to form a mulch layer. In both cases they found the clay treated plots had only a 3 percent weed cover — similar to an herbicide treatment.

However, blackberries that were planted prior to the kaolin clay treatments suffered phytotoxic damage after the clay was applied. No damage occurred in plots where the blackberries were planted after the treatment had dried, suggesting the wet kaolin clay can damage plants.

Kaolin clay was found to be an effective weed control because the 1- to 2-inch thick clay layer on the soil surface contained very little water and was very crusty, making it tough for weed seeds to germinate and grow.

Kaolin clay is available from garden centers and via mail order for pest and disease control, but more research is needed to determine how best to use it as a weed control. Stay tuned. For more information on this kaolin clay research go to the Agricultural Research Service’s Web site.

No-Mow Grass

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It's midsummer and many gardeners are getting tired of mowing the lawn. There's no getting around mowing a manicured Bermuda grass or Kentucky bluegrass lawn, but if you have an orchard, vacation home lawn, horse pasture, river bank, or steep area that where you want to grow grass but don't want to mow very often or at all, try No-Mow-Grass or No-Mow Lawn Mix.

There are both Northern and Southern versions of No-Mow-Grass. Northern No-Mow-Grass is a type of creeping bentgrass (Agrostis) that grows just 3 to 6 inches tall, tolerates shade, and has a soft, velvety feel. Southern No-Mow-Grass is a blend of fine fescue and buffalo grass. When left unmowed it will gently fold over for a natural meadow look. It is drought tolerant and stays green all summer.

Another lawn grass option is the "No-Mow" Lawn Mix. This blend of six low-growing varieties of fine fescue grows well in sun or part shade. It's best grown on sandy, loamy, and well-drained clay soils with at least four inches of good, loose topsoil. "No-Mow" Lawn mix is adapted to the cooler regions of the country such as the Upper Midwest and Northeast.

For more information on the Northern and Southern No-Mow-Grass, go to the No-Mow-Grass Web site.

For more information on the “No-Mow” Lawn Mix, go to Prairie Nursery.

 
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