Iowa State University researchers, with funding from soybean checkoff through the United Soybean Board and Iowa Soybean Association, have confirmed that over 70 isolates of the pathogen Cercospora sojina (cause of frogeye leafspot in soybeans in Iowa) are resistant to quinone outside inhibitor (QoI) fungicides.
Integrated Crop Management News
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This article summarizes our 2019 corn foliar fungicide trials that were done at six locations in Iowa: ISU Northwest Research and Demonstration Farm (NWRF), Sutherland; Northeast Research and Demonstration Farm (NERF), Nashua; Northern Research and Demonstration Farm (NRF), Kanawha; Southwest Research and Demonstration Farm (SWRF), Lewis; Southeast Research and Demonstration Farm (SERF), Crawfordsville; and the Ag Engineering and Agronomy Farm (AEA) near Boone.
The 2019 growing season was challenging for farmers in many parts of the state, especially because cold and wet soil conditions in April significantly delayed planting. Thistle caterpillar was the most abundant insect statewide, though multiple species of caterpillars, Japanese beetle, soybean aphid, and soybean gall midge were observed in soybean.
The soybean cyst nematode (SCN) has been managed for decades with resistant soybean varieties. Almost all soybean varieties have SCN resistance from a breeding line named PI 88788, and SCN populations have developed high levels of reproduction on the PI 88788 resistance. The results of a field experiment in southeast Iowa in 2019 foreshadow alarming yield loss due to SCN in the future if farmers continue to have only PI 88788 SCN resistance available in soybean varieties.
Choosing corn hybrids and soybean varieties is one of the most important crop management decisions to be made. It is a hard decision to make because it is typically made months before the growing season begins. This article will explore where to find yield trial information, how to interpret yield trials, and what to consider in selecting cultivars.
Continuous corn is a "three strikes and you’re out" situation. And the first strike is automatic – high residue volume. This is how a farmer recently described it to me.
Making continuous corn work means knowing what you are up against. First, realize that the yield drag for continuous corn can range from 0% to 30% but is typically between 5% and 15%. Yield drag has been associated with cooler and wetter soils, nitrogen (N) immobilization, increased disease risk, and allelopathy – all of which are influenced by corn residue volume.
Resistant varieties continue to be a key tool for managing the soybean cyst nematode (SCN). With financial support from the soybean checkoff through the Iowa Soybean Association, Iowa State University annually compiles a list of SCN-resistant soybean varieties that are available for use in Iowa.
The updated list of maturity group 0, I, II and III varieties is now available for free online in the Iowa State University Extension Store.
Crop residue serves an important role in physically protecting soil from erosion during rain events or high winds, as well as enhancing the soil biological activity by providing sources of organic carbon and nitrogen for its energy needs. In order to understand how residue decomposes, we need to understand how the degradation processes are influenced by environmental and soil conditions; namely, air and soil temperatures, soil moisture availability, soil pH, oxygen, and type of microbial community.
A critically important fall activity that can pay large dividends for next year’s soybean crop is sampling fields for the soybean cyst nematode (SCN). Also, some farmers might consider sampling fields in which soybeans were grown in 2019 if disappointing yields occurred for no apparent reason. This article discusses how to collect a meaningful SCN soil sample, where to send the sample to get it processed, and how to interpret SCN soil sample results from Iowa State University.
Fall nitrogen (N) fertilizer application continues to be popular for several reasons, including lower cost, time for application, equipment availability, often better soil conditions, and competing springtime field activities.