Tri-County Weed Control in Ely recently released insects to assist in the control of an invasive weed known as spotted knapweed.
Control of certain invasive weeds is mandated in the Nevada Revised Statutes, and a designation of those weeds is listed in the Nevada Administrative Code at ?555.010.
Tri-County Weed Control released beetles called Cyphocleonus achates ("C.achates") at two sites on private property in Ruth. Ruth has a severe spotted knapweed problem throughout the town, and the strategy is to begin releasing beetles to complement the herbicide control program of the local Cooperative Weed Management Area. Most invasive weeds require an integrated weed management approach that considers all forms of control methods, then control methods are selected which are most effective, especially in combination with each other.
The release of C.achates to control spotted knapweed demonstrates the local concern for effective integrated weed management. C.achates are released in an infestation of spotted knapweed. Spotted knapweed (Centaurea biebersteinii, formerly Centaurea maculosa) is native to eastern Europe and has spread to many western states in the U.S. It can be controlled by herbicides but in some areas, where the terrain is too rugged or where it is growing in sensitive areas such as waterways or around sensitive species, biological control agents like insects are the most effective way to combat the plant. So far C.achates have been released in Arizona, California, Colorado, Idaho, Minnesota, Montana, Nebraska, Nevada, Oregon, South Dakota, Utah, Washington and Wyoming as part of a program to control spotted and diffuse knapweed.
The C.achates beetles are root-boring insects that severely injure the plants. The beetles lay their eggs just below the soil surface on the roots. When the larvae hatch, they bore into the roots as they feed, helping to destroy the tap root. This opens up the root to bacteria and fungus that invade and cause further damage to the plant. The beetles will lay eggs many times during the summer and early fall, creating more larvae to feed on the roots throughout the growing season.
According to Ronald Lang, USDA APHIS in Montana, before the first beetle release in 1987, C.achates were extensively tested on 71 plant species and found to be host-specific to spotted and diffuse knapweed.
Many variables can influence the effectiveness of biological control agents such as insects. Each species has specific habitat needs, life cycle distinctions, and express requirements such as temperature, soil conditions, and/or moisture or precipitation, to be successful in inhabiting a new area and then controlling the targeted invasive plant. Many times it takes years for control insects to become established and prove effective.
Several entities were involved in the release of the 500 C.achates beetles. Tom Barbouletos of the U.S. Forest Service, Forest Health Protection, provided the beetles to Tri-County Weed Control through the Nevada Department of Agriculture. Tri-County Weed Control worked with the Steptoe Valley Cooperative Weed Management Area to identify appropriate sites to release the insects. For more information concerning weed management or the Steptoe Valley CWMA, contact either Ron Oxborrow, chairman of the Steptoe Valley CWMA, or Tri-County Weed Control in Ely.Ely Times
