The growing season in southeast Oregon and southwest Idaho again started with plenty of competition from weeds.

“It was wet, cold and windy,” Oregon State University weed scientist Joel Felix said at a research field tour June 13 at the OSU Malheur Experiment Station near Ontario. “Even at grower fields, it has been a struggle to apply products on time.”

Many weeds became established early, a function of the fairly wide temperature range over which they can grow. Weeds can be thriving by the time certain annual crops emerge, and may develop resistance to herbicides fairly quickly.

In one field on the tour, Felix showed experimental chemical treatments to control yellow nutsedge, an invasive, yield-reducing perennial in potatoes.

In another, he discussed a nematicide treatment of yellow nutsedge in onions.

This year, he has seen “a lot of yellow nutsedge, not just in onions, but in beets — and surprisingly, in corn,” he said in an interview.

Effective treatment products are available for corn, the products’ application timing is favorable, and farmers using them have “clean” fields, Felix said. While it is the grower’s choice to use the products, corn is “the crop we should use to clean up yellow nutsedge in the valley.”

Yellow nutsedge has been a major concern in southeast Oregon and southwest Idaho for some 20 years, said tour participant Glenn Letendre, an agronomic service representative with Syngenta Crop Protection.

Efforts to control nutsedge exemplify the value of attending research field days, as participants get information and updates on programs that researchers have been able to put together over several years of crop rotations, he said.

An overall benefit of OSU-Malheur’s annual weed tour is “being able to demonstrate to the industry that there is a solution to control weed problems,” Letendre said.

Letendre, who hosts research field days himself, said the events can help growers and crop consultants keep up on current trends and potential new products that can help them address problems.

He would like to see increased participation, he said.

For example, field days can provide consultants with more information that they and their clients can use to inform decisions with economic and agronomic implications.

“Everybody can benefit,” Letendre said.

How to identify invasive Palmer amaranth and waterhemp — both of which are prolific invasive weeds identified in the Northwest recently — was discussed at length at the field day.

“These species are thriving in our irrigated system,” said presenter Clarke Alder, research agronomist with Amalgamated Sugar. “They are very adaptable.”

Palmer amaranth in the past year has been found in more than 70 locations from south-central Idaho to the Ontario area, he said.

Alder, Felix and University of Idaho weed scientist Albert Adjesiwor are among scientists studying the weed, which can grow 6 to 8 feet tall.

“When you see it, please contact us,” Alder said. “We are still getting a grasp on the scope, and resistance testing.”