Grower-based selection of varieties and systems for wheat stem sawfly control

View the project final report

• 2008 annual report

Commodities

• Agronomic: wheat

Practices

• Crop Production: double cropping
• Education and Training: demonstration, display
• Pest Management: biological control, field monitoring/scouting, trap crops

Climate and marketing issues make wheat the primary crop grown in the state of Montana. A major impediment to profitable production is the wheat stem sawfly. The project has been developed to meet the objectives of Western SARE by integrating expertise of scientists and growers to develop sustainable methods for control of the wheat stem sawfly. We will develop a novel approach to sawfly control using two plant characteristics. First, wheat with solid stems suppresses sawfly damage and causes high mortality of the insect. Second, certain wheat varieties produce a high level of volatile compounds that serve to attract egg-laying females. Our goal is to develop a system whereby wheat stem sawfly females preferentially deposit eggs in attractive, solid-stemmed wheat lines. Solid-stemmed lines will be paired with hollow-stemmed, high-yielding lines in replicated field scale traits on two sawfly-infested farms in Montana. Our hypothesis is that attractive solid-stemmed lines will serve as a trap crop to protect unattractive, and higher-yielding, hollow-stemmed lines. This project presents a unique approach for sawfly control by combining high levels of plant-produced volatiles to attract the sawfly, and solid stems to kill them. The research will meet SARE national goals of enhancing the natural resource base and making efficient use on-farm resources by utilizing natural biological patterns and controls. Western SARE goals to be addressed include promotion of good land stewardship by providing regional sustainable farming methods without the use of agricultural chemicals. Our outreach plan will be led by an extension specialist, and include several formal and informal venues both in Bozeman and in sawfly-infested areas. The goal of the outreach program is to involve growers in a system-based approach for management of the wheat stem sawfly. A primary educational product will be on-site presentations, which will also be incorporated into extension and grower organization websites. The short-term outcome of this work will be a test of concept for manipulating volatile production and stem solidness in a systems-based approach to sawfly management. The medium-term impact will be increased profitability due to enhanced sawfly control and increased sawfly mortality. The impact can be measured by adoption of the system by growers in sawfly-infested areas. Two producers have agreed to assist with all levels of the proposal, from proposal writing to planting, data collection and dissemination. The Montana Wheat and Barley Committee Board of Directors has agreed to meet annually with us to evaluate progress and provide direction. The success of the outreach project will be measured in several ways, including the development of refereed and web-based published materials. In the long term, the best measure of success will be adoption of varieties and the adaptation of production systems by Montana farmers.

The objectives of the proposal are four-fold. First, we will assess the potential of solid-stemmed Choteau spring wheat as a trap crop for control of wheat stem sawfly. Second, we will select solid-stem lines from a Reeder/Choteau cross that have high end-use quality and vary in volatile production and stem solidness. Third, we
will determine the relative ability of the solid-stemmed Choteau/Reeder lines to trap wheat stem sawfly. Finally, we will provide meaningful outreach to growers regarding sawfly control in general and use of trap varieties specifically.

First-year work will entail planting farm-scale experiments in two sawfly-infested areas of the state. In these trials, solid-stem Choteau will be used as a trap alongside a highly attractive and unattractive variety, respectively. Levels of sawfly infestation will be determined for each variety combination. Selected lines from the Choteau/Reeder cross will be assayed for their ability to trap wheat stem sawfly, and suitable pairs of lines will be developed as a trap crop system. We will develop a brochure for growers describing this work and speak at a minimum of five field day events on this topic. We will also participate as speakers in at least one annual Extension Crop School and discuss our experiments with the Montana Wheat and Barley Committee.