Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2012
Publication Date: 1/9/2013
Publication URL: http://handle.nal.usda.gov/10113/60791
Citation: Boyette, C.D., Hoagland, R.E. 2013. Bioherbicidal potential of a strain of Xanthomonas spp. for control of common cockelbur, (Santium strumarium). Biocontrol Science and Technology. 23(2):183-196.
Interpretive Summary: Cocklebur (Xanthium strumarium L.) is an economically important weed in soybean, cotton and peanut production, and biotypes of this weed have also developed resistance to several classes of herbicides, making its control even more problematic. Several isolates of a previously unreported bacterial disease were discovered on common cocklebur seedlings, and were cultured and tentatively identified as Xanthomonas campestris. The most virulent isolate was used in studies to define its disease progression on cocklebur seedlings and to conduct a host range evaluation on several weed and crop plants. In addition to exhibiting high virulence on common cocklebur, it was also effective against other weeds such as marestail, giant ragweed, and common ragweed. The organism did not infect other plants tested. Results suggest that this pathogen may be useful for the biological control of cocklebur as well as some of other important weeds. This is also highly relevant since all of these weeds have evolved resistance to one or more synthetic herbicides and are thus becoming more difficult to control.
Technical Abstract: Several isolates of a previously unreported disease were discovered on common cocklebur seedlings in Chicot County, Arkansas and Washington County, Mississippi. Diseased plants in nature exhibited angular-shaped leaf spotting symptoms on leaf margins and central leaf areas. The isolates were cultured from diseased leaf tissue and tentatively identified as Xanthomonas spp., and their virulence on common cocklebur seedlings compared. The most virulent isolate (LVA987) was used in studies to define disease progression on cocklebur seedlings and to carry out a host range evaluation on various weeds and crop plants. High virulence was found on common cocklebur > marestail (Conyza canadensis) > giant ragweed (Ambrosia trifida) = and common ragweed (A. artemisifolia). These results suggest this pathogen may be useful for the biological control of these important species of weeds. This is also highly relevant since all of these weeds have evolved resistance to one or more synthetic herbicides and are thus becoming more difficult to control with conventional herbicides