May 23, 2007
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Tiny beetles are ravaging elms such as the one above. (Photo by Chris S. Corby)
Small beetle has big
appetite for elm leaves|
Tiny beetles have been ravaging North Texas elm trees this spring, said experts with Texas Cooperative Extension.
Requests for information about the elm flea weevil have poured in from five counties in the Dallas-Fort Worth area, said Dr. Mike Merchant, an Extension entomologist in Dallas.
The beetles seem to be feasting on leaves of all types of elms in the region, Merchant said. The insects appeared early this season and have been spreading quickly.
When they are done with a leaf, the beetles leave little more than a skeleton, he said.
Though small — about one-fourth the size of a grain of rice — the beetles are hard to miss, he said. Their numbers are so large in some areas, they fall out of trees onto lawns, sidewalks and people. The beetle would appear as a black speck on the tip of a finger. Its long snout can be seen under a magnifying glass.
"It's not hard to tell that they're there," he said.
But fortunately the pests are easy to kill, Merchant said. The insecticides acephate, Malathion and permethrin should work well.
The biggest challenge would be applying the insecticide to tall trees, he said. Some homeowners may need to hire a pest control professional.
Elm flea weevils will harm only elms, Merchant said, so it won't be necessary to spray other types of trees.
Most elms will recover well, he said. But some that have been stressed by a lingering drought might struggle.
Records at Texas A&M University entomology department's insect collection suggest a second generation of the beetles could appear in August, Merchant said.
Entomologists don't know much about elm flea weevils, he said. But they know the insects aren't normally a big pest.
Recent rain in the area may have helped the beetles flourish, Merchant said.
"Rain is a good trigger for outbreaks like this," he said. "There's lots of vegetation out there. That means lots of food."
Although a problem for property owners, this year's outbreak is an opportunity for entomologists, Merchant said.
"You can learn from these outbreak years," he said. "They help us make predictions and recommendations in the future."
Twenty-five warm-season turf grass varieties used throughout south and central Texas underwent initial testing to help determine their drought tolerance. The study used a specially built 5,000-square-foot drought simulator on San Antonio's south side to replicate complete drought conditions. Grasses rooted in a 4-inch soil depth and an unrestricted "native" soil depth of 18-plus inches were evaluated during 60-day drought and recovery periods. The study will be duplicated beginning in July. (Texas Cooperative Extension photo by Dr. David Chalmers)
First year of two-year
turf grass drought study complete|
By Paul Schattenberg
While the first year of a two-year study on the drought tolerance of warm-season south and central Texas turf grasses is complete, more research is needed, said a Texas Cooperative Extension expert.
"We've gotten some initial results, but we have to repeat the study again later this year to verify these results before we can say anything definitive," said Dr. David Chalmers, Extension turfgrass specialist.
Initial testing was done last year on 25 turf grasses and cultivars using a 5,000-square-foot drought simulator located on San Antonio's south side. The simulator was built by the Texas A&M University System's Irrigation Technology Center with funding from the San Antonio Water System, Turfgrass Producers of Texas and the Rio Grande Basin Initiative.
"Both San Antonio Water System and the Turfgrass Producers of Texas were instrumental in the study," Chalmers said. "They both worked with us to establish the protocol. And the producers provided in-kind services like leveling the test area and transporting, washing and installing the sod."
At the site, 200 grass plots measuring 4x4 feet were subjected to 60-day drought conditions. These conditions were maintained using a rain-out shelter — a large, low-profile galvanized metal roof that automatically covered the plots when rain was detected.
After the 60-day simulated drought, the grasses were irrigated over a 60-day recovery period to see how they responded. All grasses were evaluated through the July 23 through Sept. 20, 2006 drought period and subsequent 60-day recovery period.
Grass varieties studied included eight types of bermudagrass, seven of St. Augustine grass and nine of zoysiagrass, Chalmers said. One variety of buffalo grass was included for scientific comparison. Each was planted in a soil depth of 4 inches and in a "native" unrestricted soil depth of 18 inches or more.
The same grasses were planted in the drought simulator last fall in preparation to repeat the same experiment beginning this coming July.
"The 4-inch soil depth was chosen to 'mimic' soil conditions in the Hill Country and to help evaluate how grasses would perform based on San Antonio's conservation ordinance for new construction," Chalmers said.
The new ordinance requires residential and commercial builders to install only approved turf grasses with "summer dormancy capabilities" in new construction in the city.
"The ordinance was put in place to assist new homeowners," explained Karen Guz, conservation director at the San Antonio Water System. "New homeowners told us their struggles with grass growing on limited soil. They also wished there were rules to require tough grasses that would not be so difficult to keep alive during dry summers. But there was little evidence about which cultivars had summer dormancy capabilities. This study was an important first step."
Under the conditions of the study, no grasses in the 4-inch soil depth survived the 60-day simulated drought, Chalmers said. But all 25 grasses with a native soil depth of 18 inches or more survived.
Because none of the grasses in the 4-inch soil depth survived, initial study data focused on the grasses which survived in unrestricted native soil, he said. Among those grasses and cultivars were differences in the time to leaf firing as well as the type and amount of firing.
"Firing refers to grass color during a period of drought stress, ranging from a healthy green on the high end showing no moisture stress to a straw-colored brown on the low end showing severe moisture stress," Chalmers said "Firing is what happens when the leaf blades lose chlorophyll, and it's a primary indicator of drought stress."
Grasses were evaluated visually for drought performance, and were assigned ratings from one to nine based on how they responded to and recovered from the drought.
"We assigned ratings relative to firing and grass quality, with one being the lowest and nine being the best," Chalmers said. "Our main emphasis was on how well grasses recovered after the imposed 60-day drought."
This data was used by the San Antonio Water System to help develop a list of approved grasses for use in new construction. These include the bermudagrass varieties of Celebration, Common Bermuda, GN1, Grimes EXP, Tex Turf, TifSport and Tifway 419; the zoysiagrass varieties of El Toro, Empire, Jamur and Palisades; the St. Augustinegrass variety Floratam, and all buffalograss varieties (http://www.saws.org/conservation/Ordinance/TurfGrass/index.shtml).
"Homeowners hope for a quick recovery of their grass after a drought ends," Guz said. "To most of them, this means full coverage and little bare ground showing a few months later. We chose these cultivars with this in mind."
"We encouraged participation by A&M to provide unbiased scientific data to use in making decisions about which grasses would be allowed in new construction," said John Cosper, executive director of the Turfgrass Producers of Texas.
The study was a good one, said Cosper, whose organization represents about 70 turf grass growers across the state, but further explanation is needed to properly interpret the results. Cosper noted that fine-textured zoysiagrasses probably recovered more slowly than other grasses due to the mowing height used during the study. He also cited a 23-day delay in study's original start date leading to grasses being subjected to a "cool environment not favorable to growth" during some of the Sept. 21-Nov. 19 recovery period.
The climate during the drought was extreme with high temperatures and low humidity, he said.
"SAWS accepted some varieties and rejected others even though all 25 varieties (in native soil depth) survived," Cosper said. "We have asked them to look at the plots again this spring and to be open to accepting other varieties that demonstrate the ability to survive a 60-day drought."
Grasses in the native soil did not begin to show much leaf firing until after about three weeks under drought conditions, he said, and the water system has never limited outdoor irrigation to less than once a week.
However, grasses in the 4-inch soil began to show stress after six days and were mostly browned off after 12 days, Chalmers, added.
"One of the most important aspects of the study for conservation was finding that there are turf varieties that can go completely dormant and recover very well," Guz said. "This supports the idea that turf can be part of a sustainable landscape in South Texas, regardless of what future challenges drought may bring."
"It's important to recognize that factors involved in drought resistance should be weighted differently if water conservation objectives are different," Chalmers said. "The 60-day worst-case scenario conservation strategy for the study is very different from the San Antonio Waters System's Stage 1, 2 and 3 restrictions that would allow for different amounts of irrigation to help turf survive."
These initial results should not be interpreted as the last word on drought-tolerant grasses for the region, Chalmers said.
"Drought-resistance related to turf grass is complex and multifaceted," he said "And while this study give us some good initial data, it doesn't give us any information about how these grasses might perform at other soil depths, such as 6-, 8- or 12-inch depths."
Grasses benefit the urban landscape and environment in a number of ways, including temperature moderation, oxygen production, runoff and soil erosion reduction, dust stabilization and aesthetic enhancement, Chalmers said.
"The question is how much water is available — and (how much) are we willing to use — to sustain turf grass quality," he said. "Or better yet, the question for research to answer might be: What is the minimum amount of water we can use to achieve this end?"
More information on lawn grasses suited to south and central Texas can be found at http://aggieturf.tamu.edu.
"Never use a hose without a watering wand," writes Billy Ray Stevens, "because the pressure turns the surface of the soil to mud, which then turns to hard pan and hinders plant growth."
Have a favorite gardening tip you'd like to share? Texas Gardener's Seeds is seeking brief gardening tips from Texas gardeners to use in future issues. If we publish your tip in Seeds, we will seed you a free Texas Gardener T-shirt. Here's a chance to get published and be a garden stylist as well! Please send your tips of 50 words or less to the editor at: Gardening Tips.
Did you know...
Gardeners used to feed cabbages with beer for extra growth. Fermented hops were supposed to have the same effects as good quality compost. Don't use modern beers because the chemicals used in the brewing process will hinder growth.
Upcoming garden events
Austin: It's About Thyme, 11726 Manchaca, Austin, will host "Choosing the Perfect Crepe Myrtle for Your Garden," a free clinic for gardeners to learn about disease resistance, choices of size, and length of bloom time, presented by Hays County Free Press columnist and crepe myrtle expert Chris Winslow, Sunday, May 27, at 2 p.m. For more information, call (512) 280-1192 or visit www.itsaboutthyme.com.
Austin: The Fifteenth Annual Texas Bamboo Festival will be held on Saturday and Sunday, August 25 and 26 at Zilker Botanical Garden, Austin. Sponsored by the Texas Bamboo Society, the event will celebrate the wonders of bamboo with presentations, demonstrations and education information, including Bamboo 101, a Bamboo Kite Making Workshop led by Greg Kono, and Bamboos of Southeast Asia presented by Harry Simmons. Bamboo plants and crafts will be for sale. For additional information, call (512) 929-9565 or visit www.bamboocentral.net.
San Antonio: The San Antonio Botanical Garden is sponsoring a trip to Italy September 4 through 15, featuring Italy's villas and gardens. Escorted by Bob Brackman, the Director of the Garden, an exceptional itinerary has been designed for lovers of leisurely travel and beautiful homes and gardens. Famous for their gardens, Italians still build on their ancestors' legacy with the creation of exquisite country villas surrounded by terraced, fountain-filled gardens that have become symbolic of Italian style. Experience the rich cultural heritage of Italy. Visit special gardens, famous museums, the important cities of Florence and Rome, plus the Lake District, and the small villages which make Italy so charming, such as Cinque Terre, Santa Margherita and Tuscan villages. Feast on fabulous Italian cuisine and enjoy la dolce vita. Land cost per person sharing is $3550 plus air, which includes a $100 tax deductible donation, most meals and gratuities. For more information, contact Marianne Martz of Fuller Travel at (210) 828-6311 or email@example.com.
Rockport: The Aransas/San Patricio Master Gardener Association “Hidden Gardens Tour & Fall Plant Sale” will be held Saturday, September 29 from 9 a.m. to 4 p.m. for the Hidden Gardens Tour and 9 a.m. to 1 p.m. for the Fall Plant Sale at Green Acres, 611 East Mimosa Street at Pearl Street, Rockport. Get your tickets and maps at Green Acres for this one-day event in addition to purchasing those much-wanted plants that you can’t find anywhere. The maps will lead you to wonderful Hidden Gardens in both Aransas County and San Patricio County. Be sure to take the time to wander through the demonstration gardens at Green Acres, which are continuously being updated and maintained by the Aransas/San Patricio Master Gardener Association. Admission is $10.00. For pre-registration tickets and/or questions contact the Aransas County Texas Cooperative Extension, Rockport, at (361) 790-0103.
Fort Worth, Dallas: Visit America's very best, rarely seen, Private Gardens. The Garden Conservancy's Open Days Program has been opening the gates to America's best private gardens since 1995. The 2007 season features more than 350 gardens across 21 states. Learn about gardens participating in your area through the Open Days Directory, an annual publication listing open gardens with garden descriptions, open dates and hours, and directions. To purchase a Directory or for more information, call (888) 842-2442 or visit www.opendaysprogram.org. The $5 admission fee supports the expansion of the Open Days Program around the country and helps build awareness of the Garden Conservancy's work of preserving exceptional American gardens such Peckerwood Garden in Hempstead. 2007 Texas Open Days: Fort Worth: October 14; Dallas: October 20.
Belton, Temple, Killeen: The Bell County Master Gardener Association will host the Fall Glory garden tour Saturday, October 20, from 9 a.m. until 4 p.m. Gardens in Belton, Temple and Killeen will be showcased. Admission is $5 for adults. For additional information, contact Sue Morgan at (254) 698-8668.
Garland: The Garland Organic Club meets the first Sunday of each month in the little red school house at 1651 Wall St., Garland. All interested gardeners are invited to attend. For more information, call (972) 864-1934 or (800) 864-4445.
Austin: Austin Organic Gardeners meet at 7 p.m. on the second Monday of each month at the Zilker Botanical Gardens in Austin. For more information, visit www.main.org/aog.
Rockport: An herb study group founded in March 2003 meets the second Wednesday of every month at the ACISD Maintenance Department (Formerly Rockport Elementary), 619 N. Live Oak Street, Room 14, Rockport at 10 a.m. to discuss all aspects of using and growing herbs, including the historical uses of the herbs and tips for successful propagation and cultivation.
San Antonio: The San Antonio Herb Society meets at 7 p.m. on the second Thursday of each month at the San Antonio Garden Center, 3310 N. New Braunfels (corner of Funston & N. New Braunfels). For more information on programs, visit www.sanantonioherbs.org.
Dallas: The Rainbow Garden Club of North Texas meets the second Sunday of each month at 2 p.m. Everyone is welcome. Meetings are held at member's homes and garden centers around the area. For more information, visit www.RainbowGardenClub.com.
Dallas: The Dallas Organic Garden Club meets at 6:45 p.m. on the fourth Thursday of each month at the Fretz Park Recreation Center, located at the corner of Hillcrest and Beltline Road in Dallas. For more information, call (214) 824-2448 or visit www.dogc.org.
Arlington: The Arlington Organic Garden Club meets from 7 p.m. until 9 p.m. on the last Thursday of each month (except November and December) at the Bob Duncan Center, 2800 S. Center Street, Arlington. For more information, contact David at (817) 483-7746.
If you would like your organization's events included in "Upcoming Garden Events," please contact us at Garden Events.
The Louisiana Iris
A comprehensive guide to the culture of the Louisiana Iris, Marie Caillett and Joseph K. Mertzweiller's The Louisiana Iris represents more than 200 years of combined experience of the editors and 18 other contributing members of the Society for Louisiana Irises. This book is not available through the on-line bookstore. Limited supply available.
$29.84 while supplies last!
If you're tired of your neighbor bragging about his superior lawn, this is the book for you! Southern Lawns provides complete step-by-step instructions for planting and/or maintaining every major type of southern grass lawn, including Bermuda Grass, Centipede, St. Augustine, Zoysia, Fescue and Kentucky Bluegrass. In addition to a special "month-by-month" section with activity lists for every month of the year, author Chris Hastings includes a complete glossary of lawn care terms. This book is not available through the on-line bookstore. Limited supply available.
$26.62 while supplies last!
Noreen Damude and Kelly Conrad Bender's Texas Wildscapes helps gardeners design gardens to provide habitat for native wildlife. More importantly, it furnishes lists of beautiful and useful native plants appropriate to the specific region of Texas in which you live. This book is not available through the on-line bookstore. Limited supply available.
$26.63 while supplies last!
Order any of the above books by calling 1-800-727-9020.
(Discover, MasterCard and Visa accepted.)
Fiber row cover
Grow-Web encourages plant growth and development, and also provides protection from insects, birds, diseases and frosts. It is also air and water permeable and allows for ventilation. Grow-Web provides excellent protection to seedlings when applied directly to the seedbed.
$30.64 per 12.3' x 32.8' roll (includes shipping!)
Order by calling 1-800-727-9020. Not available through on-line bookstore.
(Discover, MasterCard and Visa accepted.)
Missed an issue? Back issues of Texas Gardener's Seeds are available at www.texasgardener.com/newsletters.
Publisher: Chris S. Corby ● Editor: Michael Bracken
Texas Gardener's Seeds, P.O. Box 9005, Waco, Texas 76714 ● www.TexasGardener.com