Watch for wet weather challenges

The growing season of 2017 continues to be a challenge for management and forces work to be done in between torrential rainfall events. Some areas of the state have already received more than 20 inches of rain since planting which is more than 8 inches above the 10-year average. This above average rainfall may seem like a huge relief, especially to those areas of the state that were in a drought last growing season, but it creates its own agronomic challenges as well.

In corn fields, the excess moisture and warm temperatures have created the perfect environment for fungal growth. Gray leaf spot, northern corn leaf blight and common rust can be found in most corn fields around the state. With the disease present and a conducive environment, the last side of the disease triangle — a susceptible host — is also needed to drive rapid infection. Product disease ratings from the seed companies would be the first place to start evaluating which products in the fields may be the most susceptible to which diseases. Products vary in their tolerance to different diseases. While a product may rate very strong against gray leaf spot, it may be weaker when it comes to northern corn leaf blight, so it is important to scout products in the field to assess which disease is present. Field conditions such as crop rotation, tillage system, planting date, and field topography can greatly influence the amount of disease present, so it is also important to scout the same product in multiple fields.

The excessive moisture and saturated soils may have caused nitrogen loss in some areas of fields as well. While at this point in the growing season it is very difficult to apply additional units of nitrogen from an operational standpoint, it is a good idea to scout those areas of suspected loss to help manage later season issues. Corn plants that exhibit nitrogen deficiency will not only limit grain fill potential, but may also have issue with stalk integrity leading to standability problems this fall. Identifying those acres now will help prioritize harvest schedule and reduce harvest problems. Nitrogen deficiency and loss can be influenced by nitrogen rate, source, timing, stabilization, drainage, soil texture, soil organic matter, and the plant’s ability to uptake nutrients. While scouting, look for the inverted yellow V pattern starting on the lower leaves of a corn plant. This is indicative of nitrogen deficiency.

Ohio’s soybean crop also has some continued agronomic challenges due to the wet growing conditions. Agronomic problems that are occurring in some soybean fields include frogeye leaf spot, white mold, bacterial blight, downy mildew, Septoria brown spot, Cercospora, and Phytophthora root and stem rot. Although diseases like Phytophthora and white mold cannot be reduced, or managed at this point of the growing season, identifying high-pressure fields can help improve management of future growing seasons. Leaf diseases of soybeans can vary greatly by product tolerance, crop rotation, tillage system, planting date, field topography and field history. So, scouting and proper disease identification can help determine if any management is needed to positively influence yield in the future.

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