The derecho left many Iowa farmers with significant volunteer corn this growing season, and unfortunately some may be facing a similar situation for 2022 after late August storms flattened fields.
Integrated Crop Management News
Links to these articles are strongly encouraged. Articles may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If articles are used in any other manner, permission from the author is required.
In a sudden turn of weather events, there have been several severe storms in the northeast and east central crop reporting districts of Iowa. These storms have created the potential for grain quality problems; of the most immediate need for action are those corn and soybean fields that have been flooded above the grain level. Fields with lodging will have more grain susceptible to flooding.
Fall armyworm is native to tropical regions in the western hemisphere. It can only successfully overwinter in the southern US (Texas and Florida), but the adults are strong flyers and capable of long-distance migration to northern states. Multiple migration events are possible each summer, and adults can be found in Iowa from June to August. This year, they are more abundant in the Midwest than usual and are causing late-season issues. As the common name suggests, larvae can still be active in October. Droughty conditions favor their development.
Since early August Iowa farmers have been reporting soybean fields or parts of fields with yellow or greenish-yellow leaves in the upper canopy which resemble early senescence and sometimes nitrogen (N) deficiency symptoms. The soybean growth stage is mainly R4 to R5. Several factors can cause these symptoms. Rainfall has been extremely variable this season in Iowa, with severe drought still persisting in some areas of the state. Yet, areas in southern and southeast Iowa have experienced normal to excessive rainfall.
Twospotted spider mites have been spotted in fields across much of Iowa already this summer, as much of Iowa is in moderate or severe drought (D1-D2, US Drought Monitor). I encourage you to scout for twospotted spider mites in crops. Twospotted spider mites can increase whenever temperatures are greater than 85°F, humidity is less than 90 percent, and moisture levels are low.
Mother Nature doesn’t always cooperate in the spring during the window for seeding forages. Thus, spring seeding may not have happened or stand establishment may be less than desired. Late summer provides an opportunity to establish forages or interseed into poor stands, assuming moisture is available. The recent rains may have some thinking about this, so below are some tips to consider helping a late summer seeding of forages be successful.
Cornfields are starting to tassle and silk all over Iowa. Many insects like to feed on silks, so it is a critical time to assess pollination rates. This article highlights a few of the most common silk feeders of importance.
In the last decade, cover crops have grown in both interest and acres, yet there is still room for more adoption across Iowa and the region. It is obvious that cover crops require more management though and with that management there will undoubtedly be challenges. In just a few weeks the cycle for cover crop establishment, growth and termination will begin.
Rainfall has been extremely variable this season in Iowa. There has been severe drought in many areas of Iowa. In contrast, rainfall has been excessive in some areas of southeast and southern Iowa. Soybean with poor growth with pale green or yellowish color has been observed in low-laying fields or field depressions with poor drainage and frequent waterlogged soils since May.
Corn tassels began showing in some Iowa fields this past week and in the next week corn in most fields will be at the R1 stage (silking). Most soybean fields are at R2 or will be at the R2 to R3 growth stage soon. Nutrient concentrations vary greatly with crop growth stage and plant part sampled. Calibrations of tissue tests based on field response trials for corn and soybean in Iowa and other states have been for leaves at the R1 growth stage in corn and the R2 to R3 growth stage in soybean.