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SALEM - Rust disease can ruin a ryegrass seed crop. And growers are worried that Tilt, the fungicide they have been using, may be losing its punch.

So Oregon State University extension agronomists have been testing new fungicides they say will tilt the balance of control back in favor of the growers.

Most promising is Quadris. "It has a totally different chemistry, and it will control rust via a different mode of action than Tilt," says Gale Gingrich, an agriculture agent in OSU's Marion County Extension Office.

During the past six years, Gingrich and Mark Mellbye, Linn County extension agent, have put several new fungicide materials in on-farm trials. As a result of the tests, four additional products have been registered for rust control by the Oregon Department of Agriculture.

The aim of the OSU tests was to give growers new options if Tilt starts to fail.

"For the past 20 years, growers have relied almost exclusively on Tilt and have used it one to three times a years on many fields," Gingrich says.

"This repeated use has caused some in the grass seed industry to worry that rust will become Tilt-resistant. If that happens, growers could lose more than half their crop in years of severe rust outbreaks. No resistance to Tilt has been confirmed. However, some growers are saying they no longer get the level of control they used to in some fields."

New fungicides registered this year are Quadris and Folicur. Gingrich says both will help the Oregon grass seed industry control rust and other leaf diseases in the future. Three years ago, the Oregon Department of Agriculture registered Sulforix and Thiolux. "These are used on a limited basis, but provide growers with an additional control when added with Tilt," Gingrich says.

The farm value of Oregon grass seed crops totaled nearly $324 million in 1997, and perennial ryegrass seed accounted for more than a third of the total. Almost all of the ryegrass seed - 150,000 acres worth - is produced in the Willamette Valley.

"Grass seed is an important crop economically and environmentally, so we want to do all we can to keep it thriving," Gingrich said.