![Photo: Tumbleweed.](https://webarchive.library.unt.edu/eot2008/20090509202215im_/http://www.ars.usda.gov/is/pr/2009/tumbleweed090319.jpg)
ARS researchers have developed a more accurate way
to predict the host specificity of potential biocontrols such as the host range
and safety of releasing the rust fungus Uromyces salsolae for control of
tumbleweed. Photo courtesy of Mary Ellen (Mel) Harte, Bugwood.org. Forest
& Kim Starr, U.S. Geological Survey, Bugwood.org. |
![For further reading](https://webarchive.library.unt.edu/eot2008/20090509202215im_/http://www.ars.usda.gov/is/graphics/For-further-reading.gif)
|
New Approach Could Improve Safety Assessments of
Biocontrol Pathogens
By
Jan Suszkiw March
19, 2009
Determining the host range of fungal pathogens that have potential for
use as biological controls of weeds should become easier to do, thanks to a new
technique developed by Agricultural Research
Service (ARS) scientists.
Their approach combines data in unique ways to improve predictions
about how certain plants or crops related to a targeted weed might react to the
release of a candidate pathogen used in a classical biocontrol program.
Existing methods of determining a pathogen's host range can be
labor-intensive, too reliant on narrow data sets, or impractical to use when
numerous or hard-to-grow plant species are involved. The new approach also
diminishes uncertainty as to whether the reactions of greenhouse-grown plants
will reflect the species as a whole under field conditions, according to a
paper published in Biological
Control and authored by
Dana
Berner, Bill
Bruckart,
Craig
Cavin and
Jami
Michael, who work at the
ARS
Foreign Disease-Weed Science Research Unit in Frederick, Md.
Their approach involves integrating plant-disease reaction scores and
other data with a matrix made up of DNA sequence information that shows the
genetic relatedness of plant species to each other and to the target weed.
Using a statistical approach similar to so-called "animal mixed models,"
scientists can predict the probable susceptibility of different plants to the
weed pathogen. This may also narrow the list of plants necessary for planning
quarantine studies.
Berner's team has used the approach to determine the host range and
safety of releasing the rust fungus Uromyces salsolae for biological
control of Russian thistle, Salsola tragus, more commonly known as
tumbleweed. Of 64 species analyzed using the mixed-model equation, only
seven--all Salsola--showed susceptibility to the fungus, indicating its high
specificity.
Although symbolic of the Wild West, tumbleweed is a noxious pest. It
can infest crop fields, harbor pathogens, deplete soil moisture, pose a fire
hazard and endanger motorists. Biocontrol offers a sustainable alternative to
herbicide spraying and physical controls like mowing, especially across large
swaths of infested land.
ARS is the principal intramural scientific research agency of the
U.S. Department of Agriculture.