Interactions between the root pathogen Rhizoctonia solani AG-8 and acetolactate-synthase-inhibiting herbicides in barley.
BACKGROUND
The widespread acceptance of reduced-tillage farming in cereal cropping systems in the Pacific Northwest of the United States has resulted in increased use of herbicides for weed control. However, soil residual concentrations of widely used imidazalone herbicides limit the cultivation of barley, which is more sensitive than wheat. In addition, increased severity of the root rot disease caused by Rhizoctonia solani is associated with reduction in tillage. Many crops exhibit altered disease responses after application of registered herbicides. In this study, the injury symptoms in barley caused by sublethal rates of two acetolactate synthase (ALS)-inhibiting herbicides, imazamox and propoxycarbazone-sodium, were assessed in factorial combinations with a range of inoculum concentrations of the root rot pathogen Rhizoctonia solani AG-8.


RESULTS
Both herbicides and pathogen had negative impacts on plant growth parameters such as root and shoot dry weight, shoot height and first leaf length, and interactions between pathogen and herbicide were detected.


CONCLUSIONS
The results suggested that sublethal rates of herbicides and R. solani could alter severity of injury symptoms, possibly owing to the herbicide predisposing the plant to the pathogen.
Department of Crop and Soil Sciences, Washington State University, Pullman, WA, USA.
Hyejin
H
Lee
Steven E
SE
Ullrich
Ian C
IC
Burke
Joseph
J
Yenish
Timothy C
TC
Paulitz
D000095:Acetolactate Synthase / Q000037:antagonists & inhibitors*; D001565:Benzoates / Q000009:adverse effects; D004791:Enzyme Inhibitors / Q000009:adverse effects*; D006540:Herbicides / Q000009:adverse effects*; D001467:Hordeum / Q000187:drug effects* / Q000254:growth & development / Q000382:microbiology*; D007093:Imidazoles / Q000009:adverse effects; D010935:Plant Diseases / Q000382:microbiology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000382:microbiology*; D012232:Rhizoctonia / Q000472:pathogenicity*; D014230:Triazoles / Q000009:adverse effects
D001565:Benzoates; D004791:Enzyme Inhibitors; D006540:Herbicides; D007093:Imidazoles; D014230:Triazoles; C471815:propoxycarbazone; D000095:Acetolactate Synthase; C494197:imazamox