Glyphosate effects on ground cover of tall fescue waterways and estimated soil erosion

ABSTRACT:

Glyphosate use for controlling weeds has increased in the Midwest, but drift or overspraying can damage tall fescue waterways. Farmers and conservation agents fear that glyphosate may reduce tall fescue ground cover in waterways and increase soil erosion. Glyphosate was applied in mid-May to tall fescue waterways at several rates from 0.14 to 2.24 kg ai/ha¹ + ammonium sulfate (2% by volume) to simulate drift or direct overspraying. Percentage cover of live and dead tall fescue, broadleaf weeds, and bare soil was measured after treatment at two sites in Missouri, and annual erosion was estimated using revised universal soil loss equation (RUSLE) software. Total (live + dead) tall fescue ground cover remained greater than 88% even at 10 to 11 months after treatment. Enough live tall fescue remained to grow into gaps. Glyphosate drift at low rates or single accidental incidents of overspraying glyphosate up to 2.24 kg ai/ha are unlikely to permanently damage tall fescue waterways.