By Robert Fears
The water guzzling plant Native to Europe and Asia, salt-
cedar (Tamarisk spp.) was intro- duced into the U.S. as an ornamen- tal and sold by nurseries beginning in the 1800s. In the early 1900s many people began establishing the plants along waterways and stream banks for erosion control. By the 1920s it was determined that saltcedar was going to be a major problem because it began rapidly spreading from one watershed to the next. “Most saltcedar are decidu-
ous shrubs or small trees typical- ly growing 10 to 30 feet tall and forming dense thickets,” said Hart. “A few saltcedar species are ever- green. Young twigs and stems have a smooth, reddish brown bark. The leaves are very small and scale-like, about 1/16 inch long. They often have a crust-like scale from salt secretions.” As its name implies, saltcedar
can tolerate salinities as high as 15,000 parts per million (ppm), whereas natives such as cotton- woods and willows typically must have salinities below 2,500 ppm to survive. “From March to September, the
plant produces small white, pink or purple fl owers in dense masses on its stem tips,” said Hart. “It is cross- pollinated by wind and can produce up to 500,000 seeds per plant each
tscra.org
year during April through October. The seeds can be dispersed long- or short-range, primarily by wind or water. Saltcedar germinates, adapts and survives in a wide range of en- vironmental conditions.” Saltcedar can rapidly colonize
riparian and shallow water table areas. In addition to seeds, it vig- orously reproduces from root buds, especially after a fi re or mechani- cal disturbance. The leaves excrete salt on the soil surface, which can kill nearby desirable vegetation. The plant out-competes native veg- etation for sunlight, moisture and nutrients. Saltcedar aggressively grows roots down to groundwater and uses large amounts of water through transpiration.
The hungry bug The saltcedar beetle (Diorhabda
spp.) has been introduced into the U.S. from northern China, Uzbeki- stan, Crete and Tunisia. Research studies have shown that beetles collected from different locations can have varying effi cacy and es- tablishment potential. Releasing in- sects from different points of origin maximizes potential establishment and success in saltcedar control. “Saltcedar beetles are yellow to
yellow-brown, about ¼ inch long and shaped like a cucumber bee- tle,” said Dr. Allen Knutson, Ex- tension entomologist with Texas
A&M AgriLife Extension Service at Dallas. “Eggs are deposited in masses of up to 20, which are glued to saltcedar foliage. The eggs hatch in about 5 days. “When small, the larvae are
black,” Knutson said. “Larger lar- vae are black with a yellow strip along each side. Full-grown larvae are about 1/3 inch long. The larvae feed on saltcedar foliage for about 3 weeks and then crawl or drop to the ground, where they pupate in the leaf litter on the soil surface. About a week later, adult beetles emerge from the pupae. Two or more gen- erations are completed each year. During the winter, adults survive beneath the leaf litter and in bunch grasses on the soil surface.” Beetle larvae and adults feed on
the small, scale-like leaves of saltce- dar, causing them to turn brown and die. Larger larvae and adults may also feed on the bark of small twigs, causing the ends to die. A large infestation of larvae can quickly defoliate saltcedar trees. Although the trees can grow new leaves, they are not expected to be able to with- stand repeated feeding by several generations of beetle larvae. “Biological control is a sustain-
able approach that can suppress saltcedar in the long term,” ex- plained Knutson. “Control may be slow initially, but once beetles are established in an area, they should
May 2013 The Cattleman 61
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