Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2009
Publication Date: 8/20/2009
Citation: Babiker, E.M., Hulbert, S., Burke, I.C., Paulitz, T.C. 2009. Influence of weed species and time of glyphosate application on Rhizoctonia root rot of barley. Phytopathology 99: S6 Interpretive Summary:
Technical Abstract: Rhizoctonia solani AG-8 causes root disease in wheat, barley, canola and other small grains in the dryland inland Pacific Northwest. The pathogen survives between crops on roots of volunteers and grassy weeds. Destroying this green bridge with herbicides such as glyphosate is a common tactic to control this disease. But little is known about the optimal time between glyphosate application and planting, to allow enough time for Rhizoctonia inoculum to be degraded by other soil microorganisms to reduce disease severity in the following crop. The impact of pre-plant glyphosate application times to control weeds on incidence and development of Rhizoctonia root rot disease of barley (Hordeum vulgare L.) was investigated under a controlled environment. Wild oat (Avena fatua L.), Italian rye grass (Lolium multiflorum), and downy brome (Bromus tectorum L.) were planted in soil infested with R. solani AG-8. Pots were sprayed with glyphosate at 6 wks, 4 wks, 2 wks, 1 wk, and 2 days before planting with barley. Plant measurements were taken three weeks after planting. Weed species, time of application and treatment interactions had significant (P < 0.05) effects on shoot length, root length, disease rating fresh weight and dry weight. The highest disease ratings were seen at 2 wks after spaying, but declined at 4 and 6 wks. The timing of glyphosate application and weed species are crucial factors in managing the greenbridge.