While row crops are generally the focus of attention this time of year, spring is a great time to scout for winter injury in alfalfa fields and assess stand health. This is especially true if stands did not have adequate snow cover or were covered by sheets of ice during the winter. Several other factors may contribute to alfalfa winter injury, including soil moisture, 4-inch soil temperatures, and other stresses like soil fertility, stubble height, as well as the age of the stand.
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.
Prepare for a safe pesticide application season by checking the FieldWatch® registry before making pesticide applications. The FieldWatch® registry provides easy-to-use, accurate, and secure online tools to enhance communications and awareness between crop producers, beekeepers, and pesticide applicators. FieldWatch® features a voluntary mapping tool through Google Maps™ that shows pesticide applicators the locations of registered sensitive crops and beehives so they can make informed decisions regarding pesticide applications.
Pesticide residues can be carried on your clothing even if you wear personal protective equipment (PPE) over your own work clothes. Therefore, it is important to properly clean your clothes after working with and around pesticides. Many pesticide labels provide limited instructions for cleaning work clothes. In situations where no instructions are provided, follow these guidelines for washing contaminated clothing.
Guidelines for soil-test phosphorus (P) and potassium (K) interpretations and application rates were last updated in 2013. Since then, significant field research was conducted to assure that nutrient management guidelines are kept current. The new response data, increased crop yield levels in Iowa, and better awareness of usually large spatial soil-test variability in production fields indicated a need for adjusting the boundaries of soil-test interpretation categories and suggested nutrient application rates.
A list of SCN-resistant soybean varieties for use in Iowa is compiled and made available every fall as ISU Extension publication PM 1649. The updated list recently has been made available online. Overall there are fewer SCN-resistant soybean varieties than in past years, but there are varieties from more brands (27) in this year’s publication. Most importantly, there are 47 varieties with Peking SCN resistance in the 2022 list, which is 13 more than were in the list in 2021. Soybean varieties with Peking SCN resistance are highly valued because they limit reproduction of Iowa SCN populations much more than varieties with the common PI 88788 resistance.
With harvest winding down, one weed that made harvest more frustrating for some is burcucumber. Consequently, there have been many questions on how to better manage this weed to prevent those frustrations.
Iowa State conducts soybean cyst nematode (SCN) experiments in fields rented from farmers in all of Iowa’s crop reporting districts. Spring soil samples from each study area are used to test the SCN population in the field for levels of reproduction on soybean breeding lines with SCN resistance genes. The results of testing in 2022 revealed some SCN populations with 75% to 90% reproduction on PI 88788, the source of SCN resistance genes present in almost all of the soybean varieties available in Iowa. This high level of reproduction makes complete loss of effectiveness of PI 88788 SCN resistance seem possible within several years. The number of varieties with more effective Peking SCN resistance is increasing every year, but the rate of increase is not keeping pace with the increase of reproduction of SCN populations in Iowa fields on PI 88788 resistance. An active, integrated approach to managing SCN in Iowa is more important than ever.
With harvest in full swing and while conditions have generally been good for in-field drying this fall there are still some corn fields in areas of the state with moisture levels in the low to mid 20s.
Getting fields sampled for SCN is a task that should be on every farmer’s to-do list this fall. SCN soil samples can be collected from corn fields after harvest to determine what levels of the nematode are present to infect the 2023 soybean crop. Results of soil samples collected from fields of harvested soybeans this fall will show if SCN was present and reveal what effect the nematode might have had on soybean yields in 2022. Reproduction of SCN is greatest in dry years, and SCN egg numbers in the soil are expected to be high in soybean fields this fall. This article outlines guidelines for sampling fields for SCN, gives information on where to send SCN soil samples, and provides guidance on managing fields that are infested with SCN.
October began dry across most of Iowa except for some areas in southern and southeast Iowa. These conditions are allowing for rapid harvest progress. The outlook for the rest of the month calls for lower than normal rainfall. Below normal rainfall since August until the soil sampling time may result in lower than expected soil test results for phosphorus (P), potassium (K), and pH. Therefore, farmers and crop consultants should interpret those soil test results with caution.