Herbicide found in tainted fungicides

Batches of fungicide marketed under the names ALT 70 and Viceroy 70DF have been voluntarily recalled by NovaSource, a business unit of Tessenderlo Kerley, after a string of recent incidences of damaged turf on golf courses were traced to quantities of the products tainted with the herbicide sulfometuron methyl, the company says.

ALT 70 is marketed and distributed by United Turf Alliance and Viceroy 70DF is marketed and distributed by United Phosphorus Inc. Both are post-patent systemic fungicides manufactured by NovaSource TKI. Each contains the active ingredient O-ethyl phosphonate (aluminum tris) is labeled for control of anthracnose, Pythium and Phytophthora.

• Golf course superintendents reported cool-season turfgrass stopped normal spring green up and stopped responding to normal treatments after fungicide and growth regulator programs were initiated. ALT 70 was one of the products in the program.
• Slowing of turfgrass growth was noted in both bentgrass and bent/Poa mixed stands on greens, collars and approaches. Symptoms generally were noticeable 7-14 days after application.
• Older varieties of bentgrass (particularly older German bentgrass) and 8-10-plus year-old Penncross varieties seem to be more susceptible to decreased turf quality and turf loss, whereas newer varieties of bent seems to decline temporarily, but recover more quickly. In mixed stands of bent/Poa, the Poa also recovered and survived much better than bent varieties in the same stand. On one course, areas of ryegrass collars were also affected.
• Turf loss also seemed to occur rapidly on at least one golf course when turf showing signs of stress (purple bentgrass leaves) received a soil drench application of a of Pythium fungicide tank mixed with a biological nematicide.
• It was generally noted that turf growth was reduced for several weeks after applications of fungicide tankmixes that contained ALT 70 with previous or subsequent applications of growth regulators. Once turf declined, some turf did not recover and some turf seems to be taking several weeks to recover.
• Additional observations noted that where aeration cores were pulled and previously top-dressed (last fall or early spring) and newly established bentgrass was growing in the topdress-filled holes, turfgrass recovered and survived much better in the holes than turf in close proximity but not in the aeration holes. The plugged pattern of turf survived better for some unknown reason. Speculation includes better drainage on those roots in the fresher sand and potentially higher oxygen exchange in the holes. It may be possible that whatever product(s) ended up harming the turf was held in the plant or soil longer outside the punched areas than inside the aeration holes.