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It is not easy for insects to survive Iowa winters. Some literally can’t - they freeze to death (corn earworm, black cutworm) or migrate to warmer climates (potato leafhopper). Insects are unlike mammals and birds because they must generate their own heat (called ectotherms). Insects die when they are exposed to temperatures below the melting point of their body fluids, termed the lower lethal temperature.
Soybean foliar fungicides were evaluated for foliar disease management and yield response across seven Iowa State University research and demonstration farms in 2018. These included the Northwest Research and Demonstration Farm (Sutherland), Northern Research and Demonstration Farm (Kanawha), Northeast Research and Demonstration Farm (Nashua), Central Iowa Research Farms (Ames), Armstrong Memorial Research and Demonstration Farm (Lewis), McNay Memorial Research and Demonstration Farm (Chariton), and Southeast Research and Demonstration Farm (Crawfordsville).
In 2018, we tested various foliar fungicides on corn 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 near Boone.
Although there are many ways weeds escape control in crop fields, one of the leading causes of waterhemp control failures is emergence of plants following postemergence herbicide (POST) treatments. Waterhemp requires more than twice as many growing degree days to reach 50% emergence as giant foxtail or velvetleaf (Figure 1), resulting in much of the population emerging after mid-June.
Each year, Iowa State University evaluates the agronomic performance and nematode control provided by hundreds of soybean varieties that are resistant to the soybean cyst nematode (SCN). The research is funded by the soybean checkoff through the Iowa Soybean Association, and the experiments are conducted in each of Iowa’s nine crop reporting districts. A report containing the results of the 2018 experiments will appear in an upcoming issue of the Iowa Farmer Today. The results show that even low SCN soil population densities in the spring can increase greatly during a growing season and cause yield loss. And the yield benefits of SCN control provided by good resistant varieties are apparent in the results.
With this year’s harvest of soybeans delayed beyond what is considered an ideal window of time, the opportunity for diseases to infect seed pods and in some instances, to the seed itself, was greatly increased. Across the state and the north central region, seed suppliers have reported that this year’s crops of seed soybean are frequently testing positive for the Diaporthe fungus (Phomopsis seed decay), which is resulting in lower than normal germination rates of seed. Seed decay is characterized by cracked, shriveled seed with white chalk-colored mold on the seed surface.
On October 31, 2018, the EPA made the long-awaited announcement regarding dicamba registration for use on dicamba-resistant soybean. I suspect opinions regarding the EPA actions are as varied as people’s views of the technology. Following are pertinent changes on the dicamba labels:
As the season approaches its conclusion and harvest conditions are most challenging, there are few things worth remembering to protect and sustain soil health. At this time, soil is susceptible to compaction due to rain and saturated soil conditions. Soils remain saturated longer at this time of the year since water use by crops is negligible and there is low water evaporation due to cool temperatures.
SCN-resistant soybean varieties are critically important for managing the soybean cyst nematode (SCN). Iowa State University compiles a list of SCN-resistant varieties for Iowa farmers every year. The updated list has just been released, and it contains both fewer and more choices for 2019. Read the article to learn how this is possible.
