Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2002
Publication Date: 9/1/2002
Citation: DONALD, W.W. GLYPHOSATE EFFECTS ON GROUND COVER OF TALL FESCUE WATERWAYS AND ESTIMATED SOIL EROSION. JOURNAL OF SOIL AND WATER CONSERVATION. 2002. V. 57. P. 237-243.
Interpretive Summary: 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 fear 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. While Roundup Ultra at low to high commercial rates damaged tall fescue at one month 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 (> 88%) 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. This is good news for farmers and herbicide manufacturers who are concerned about replanting herbicide-damaged grass waterways, as well as conservationists, environmentalists, and NRCS personnel who wish to limit soil erosion.
Technical Abstract: Technical Summary: Glyphosate herbicide use for controlling weeds has increased because of the widespread adoption of glyphosate-resistant soybean and corn and no-tillage in the Corn Belt. However, glyphosate drift or over-spraying in spring may damage tall fescue in grassed waterways or field borders, reducing its effectiveness for trapping sediment. The impact of glyphosate on tall fescue ground cover was evaluated at two sites in central Missouri. Glyphosate was applied in mid- May to well-established tall fescue sod waterways at rates from 0 (untreated check) to 2.24 kg ai/ha plus ammonium sulfate (2% by volume). Percentage cover of live and dead tall fescue, broadleaf weeds, and bare soil were measured over time. Total (live + dead) tall fescue ground cover remained > 88% even at 10 to 11 months after treatment. Enough live tall fescue remained to fill gaps. Consequently, glyphosate at commercial rates sis unlikely to damage tall fescue grassed waterways for controlling erosion.