Full TGIF Record # 37947
Item 1 of 1
Publication Type:
Content Type:Abstract or Summary only
Author(s):Johnson, David R.; Wyse, Donald L.
Author Affiliation:Research Associate and Professor, University of Minnesota, St. Paul, MN 55108
Title:Biological control of Canada thistle in roadsides
Meeting Info.:December 7-9, 1993, Kansas City, MO
Source:Proceedings of the North Central Weed Science Society. Vol. 50, 1995, p. 159.
# of Pages:1
Publishing Information:Champaign, IL: North Central Weed Science Society
Keywords:TIC Keywords: Biological control; Cirsium arvense; Roadside turf; Pseudomonas; Disease control
Abstract/Contents:"The phytopathogenic bacterium Pseudomonas syringae pv. tagetis (PST) causes natural epidemics of apical chlorosis in Canada thistle and certain other Asteracea. We have isolated the bacterium from Canada thistle and demonstrated its potential as inundative biological control...The purpose of this study was to determine biocontrol efficacy of inundative PST applications for Canada thistle control under roadside conditions. Plots (9m²) were replicated three times at three sites in roadside infested with Canada thistle. Soils were waterlogged silt loam, dry, compacted, silty clay with wood chip mulch, and well-drained sandy clay loam at sites 1, 2, and 3, respectively. Vegetation at sites 1 and 3 was predominantly smooth brome; site two was a landscaped area covered by smooth sumac. Treatments consisted of one application of aqueous PST suspension (1 by 10⁹ colony forming units/ml) with organosilicone surficant (0.2% v/v). Three control plots were treated with aqueous surfacant, and three were left unsprayed at each site. Symptoms appeared on all inoculated Canada thistle within four to five days (disease incidence 100%). Infected plants were severely stunted relative to controls. Tissue that developed after treatment was yellow or white, and sometimes became brown and necrotic. Tissue formed before treatment was not affected. Nontarget plants were not injured by treatment or control applications. Canada thistles were not visibly injured surfacant controls. Disease severity and percentage of stems bearing seed were recorded for the current season. Number of stems/m² were measured for each transplant in June of the following season. There were no signficant (p=0.05) differences in seed production or stem number among nonsprayed and aqueous surfacant controls. Both seed production and stem number were significantly (p=0.05) reduced by treatments at all three sites. These data suggest PST might be used in roadside Canada thistle management, but efficacy is greatest where competition and growing conditions impact Canada thistle vigor."
Note:This item is an abstract only!
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Johnson, D. R., and D. L. Wyse. 1995. Biological control of Canada thistle in roadsides. Proc. North Cent. Weed Sci. Soc. 50:p. 159.
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