Iowa State just released its annually updated list of SCN-resistant soybean varieties online. There are more than 1,000 different named varieties from which to pick. Unfortunately, 973 of the varieties have the same source of resistance genes, on which Iowa SCN populations have built up increased ability to reproduce.
Integrated Crop Management News
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Now more than ever, farmers need to know if their fields are infested with SCN and at what levels, especially for fields in which soybeans will be grown in 2018. This article explains why and how to determine SCN numbers in fields.
The EPA recently announced changes to the new dicamba labels in response to widespread off-target plant injury in 2017. The most significant change is classification of the new dicamba formulations as Restricted Use Products. Other changes will reduce the hours available to spray soybean, including 1) restricting applications to between sunrise and sunset, and 2) reducing the maximum wind speed during application from 15 mph to 10 mph. The ability to cover all acres in a timely manner has always been an issue and these new limits will add to that difficulty.
Recently there have been many questions about how to check fields for plant-parasitic nematodes that can damage corn. Unfortunately, the situation cannot be accurately assessed with samples collected in the fall. This article discusses when and how to sample for plant-parasitic nematodes that feed on corn.
When you think about which hybrids to plant next season, make sure to take into account all the relevant factors. When selecting hybrids, prioritize yield potential and risk management. There are a number of other components to consider as well, including transgenic options, disease tolerance, maturity, grain dry down, standability, stalk quality, and early season vigor ratings.
When looking for soybean varieties, it is important to give as much thought to the process as you give to choosing corn hybrids. If you only choose one or two soybean varieties and do not take into consideration management and environmental factors of your operation, you are likely limiting yield potential.
Marestail (Conyza canadensis) is one of the most difficult weeds to manage in no-till soybean. While classified as a winter annual, the plant has significant emergence in both late summer/early fall and in the spring. This extended emergence period greatly complicates management since the success of postemergence products is closely tied to plant size. Attempting to control populations at the time of planting often results in control failures as fall-emerged plants are too large for acceptable control.
Corn harvest is fast approaching. This year’s corn maturity is about 5-10 days behind normal. With field dry down occurring in late September and October this year, there is the potential for a later harvest of corn at a higher moisture content. The rule of thumb has been that corn dries at a rate of 0.5 to 1.0% per day in September, 0.25 to 0.5% per day in October, and almost no drying occurring in November. Of course, these rules of thumb can change with favorable or unfavorable weather conditions.
Soybean are nearing maturity across Iowa with minimal delay due to cool temperatures compared to 2016. However, soybean sensitivity to day length speeds up crop development towards physiological maturity. During senescence carbohydrates are converted into oils. Soybean seed moisture changes very little, remaining near 60 percent during the de-greening period. As the pods turn to mature color at the beginning of maturity stage (R7), seed dry matter accumulation is complete and seed moisture rapidly decreases.
The dry conditions in some areas of Iowa in 2017 have raised several soil fertility questions. In some cases, there has been relatively normal crop production and no need for management changes. In other situations with severely damaged crops, there is potential for adjustments for the 2018 corn crop.