By Mari Radtke
The Iowa State University Northwest Research Farm located just southeast of Calumet hosted their annual tour on Wednesday July 7. The annual event hosted about 130 people with opening statements by the Dean of the College of Ag, Dr. Daniel Robeson. The tour featured discussions of an emerging insect problem, “Soybean Gall Midge” and an update about the long-term pest, corn rootworm. The plot testing methods to control herbicide resistant waterhemp with a discussion of the varying tests and results was a stop in the tour. The third on-site discussion provided insight to water quality.
Joel DeJong, ISU Extension Crops Specialist for Northwest Iowa opened the program with an overview of area rainfall. He noted that northwest Iowa, on average, is 5.5 inches below the 30-year average of rainfall. He explained that the tiles stopped running and that no samples (for water quality testing) have been taken for about 5 weeks. Each bioreactor drains 30 acres and is tested for water quality.
Dr. Robeson, Dean of the College of Agriculture spoke. He has been in the Dean’s chair for about 2 years. This is his first visit to northwest Iowa. He explained the effects of legislative tax cuts on the university system and how those tax cuts shifted support for the universities in Iowa from taxpayer funded to more user funded, resulting in the high tuition increases. At the same time enrollment declines, particularly out of state students who pay a higher tuition rate, are having an additional affect on budgets. He explained the 20% across the board budget cuts and how each location is reacting to those cuts. He reassured the crowd that the programs are not being cut. The focus is for students 3 years out from their traditional freshman year.
An amazing feat he explained pulled off by University staff was that in March 2020 there were fewer than 100 online courses offered and 6200 students in classrooms. Ten days later, because of COVID, all students and classes were being delivered online. When asked about the results of the online program he recognized that the real outcome will be known over time.
The soybean gall midge is a fairly new species first identified in the Linn Grove area and Nebraska in 2017. Since then 31 counties in western Iowa from top to bottom and in 5 states are having soybean fields affected by the tiny bug. This midge is a very small fly. It’s larvae can be found inside the lower stem of a soybean plant, right above the soil line. Several treatment trials and various control and efforts have been conducted with little result. How the adult midge travels is also not clear, but carried by wind is a leading theory. This midge has now been identified on the research farm. Damage from the midge is first seen on the outside 8-10 rows and works inward on a field. No successful strategies have been found to combat this midge. This is the third year of studying the gall midge.
Updates about controlling the rootworm was also explained. Scouting for adults in the field is highly recommended as a first course of action. This should happen in 6-8 weeks.
It was reported that the western corn rootworm is showing resistance to 3 out of 4 Bt traits in Iowa and that resistance in increasing.
Controlling waterhemp is a challenge and no effective treatment has been identified. Crop rotation is not effective. Herbicide treatment is not showing good results. Currently the use of chaff lining is being explored and showing some positive results. Making and applying chaff requires some investment into machinery. The process is being used in Australia to limited success.
Several methods to reduce nitrates in runoff water are underway at the research farm. Bioreactors have been in use since 2014. The untreated runoff was tested at 12-14 ppm. Drinking water standard is 10 ppm. With a bioreactor the results are showing 8 ppm. Wood chips and other bio materials are used to run the water through carbon sources to remove nitrates. Other mediums are being tested that are less expensive or require as much maintenance.
Another water purification method under evaluation is a saturated buffer that uses shallow ground water flow to remove nitrates. This method requires significant field space, 80-100 acres. Additional field conditions are required for the saturated buffer to have an affect on water quality.
The third method discussed was the installation of wetlands. Field scale of 1000 acres or more is necessary to get advantages from installing a wetland. Wetlands are typically installed at the bottom of a watershed and indicate 50% removal of nitrates from the runoff water that flows through them. Other benefits of a wetland are the improvements to habitat for wildlife and waterfowl. All practices will be needed to work sufficiently. All methods do carry a cost.
By Mari Radtke