Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 13, 2001
Publication Date: N/A
Technical Abstract: Roundup (glyphosate) herbicide use for controlling weeds has increased in the Corn Belt because of widespread adoption of Roundup-Ready (glyphosate- resistant) soybean and field corn varieties and no-tillage production practices on highly erodible land. However, soil conservationists feared that glyphosate drift or overspraying may damage nearby tall fescue planted dfor ground cover in grassed waterways or field borders. Reducing tall fescue ground cover could prevent waterways from trapping sediment and minimizing soil erosion. The long-term impact of spring-applied Roundup Ultra at various rates on tall fescue ground cover was studied at two grassed waterways in central Missouri. Live tall fescue cover, dead tall fescue cover, broadleaf weed cover, total live + dead ground cover, and bare soil were measured from digital photographs and were used to estimate soil erosion using RUSLE (Revised universal soil loss equation) software. While Roundup Ultra at low to high commercial rates damaged tall fescue by one months after treatment, Roundup Ultra is unlikely to reduce the effectiveness of tall fescue grassed waterways for controlling erosion in the long run. By 10 or 11 months after treatment, total live + dead tall fescue ground cover remained great enough (> 90%) to prevent erosion. Enough live tall fescue cover remained to regrow and fill in gaps in the two waterways. Mowing tall fescue to simulate spring grazing four weeks before Roundup Ultra spraying did not reduce tall fescue ground cover at 10 or 11 months after treatment.