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Harvest is underway and watch for stalk rot.

Harvest is underway and watch for stalk rot.
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            We have started to see some movement out in the fields with harvest underway. In terms of corn, some silage has been chopped, high moisture corn is being harvested, and seed corn fields are quickly drying down and are starting to get picked. Soybean fields have lost a lot of their leaves and are drying down quickly. A few soybean fields have already been harvested and it won’t be long before several more will be picked in the area. As a reminder to everyone, this is a very busy and stressful time of year for our farmers. When driving to and from work, please be cautious and courteous of large equipment being moved from field to field. We are going to see several trucks, tractors, and combines moving in the area for harvest. Give yourself plenty of time to get to work in the morning and give them a wave as you pass by. Farmers give up a lot of family time during the fall to bring in a bountiful harvest. Show them your appreciation for their hard work instead of honking as you drive around them!

                Stalk Rots: The major topic of concern at this point of the growing season is the potential for stalk rot damage in corn fields. Corn has been drying down fast this year and while some of that is natural, some dry down may be contributed to late season disease issues. We have received quite a bit of rain in the area during the month of September. Standing water and saturated soils can contribute to the development of stalk rots. Stalk rots can weaken corn stalks which can cause issues with standability. Lodging, stalk breakage, and premature plant death is often a result of stalk rots, which can lead to yield loss and difficultly while harvesting. Another issue to consider is that if the corn crop has stalk rot issues and stalk quality or strength has been compromised, it is common for ears to drop during harvest. This can lead to issues with volunteer corn next year. Several fields in the area had problems with volunteer corn in 2018 thanks to the wind storms that occurred in October last year. I have already heard of some folks in the area who have noticed corn ears on the ground due to wind damage. Hopefully, the extent won’t be near as bad or widely distributed as last year.

                There are several different types of stalk rots that can occur at this point of the growing season. Often times we see stalk rots develop in fields that experienced some sort of damage throughout the year, including hail and wind damage or foliar disease pressure. Excessive rainfall or ponding may also contribute to stalk rot development and other characteristics like hybrid selection, or planting population may increase the risk for stalk rots and lodging in the field. If any of this pertains to your fields and you’re concerned that stalk rots could be an issue this fall, the question you may be asking is “how do I know if my field has any stalk rots?” There are two ways you can easily evaluate potential stalk rot damage. The first method is called a Push Test. Walk a little ways into your field and randomly select at least 100 plants, more is better for good measure. Place your hand on the plant, typically on any portion of the plant that’s above the ear leaf, and extend your arm out away from you. The rule of thumb is to push the plant out about 30 degrees from its natural upright position. If the plant doesn’t snap back to normal or it remains bent when you let go, there’s a good chance you have stalk rot in that field. Another method that some folks prefer over the Push Test is to conduct the Pinch Test. Some folks like this method better because some of the guess work is taken out in deciding if the plant bounced back to normal or not when conducting the Push Test. To use the Pinch Test method, select a plant and find one of the lowest internodes on the plant. The closer to the brace roots the better. Using your thumb and index finger, pinch the internode. If the stalk crushes easily between your fingers, you may have stalk rot. If more than 10% of the plants tested in the field are confirmed to have stalk rot, it’s a good idea to harvest that field sooner rather than later. If you are still uncertain if there is stalk rot or if the stalk has been compromised in any way, you can cut the stalk open lengthwise and look to see if the inside is discolored, if the pith is hollow or spongy, or if the vascular bundles (conductive tissues) are stringy and loose.

                There are several different types of stalk rots that can infect your fields. Common stalk rots found this time of year include Fusarium stalk rot, Gibberella stalk rot, Anthracnose stalk rot, and Charcoal rot. More information about each disease can be found on UNL’s CropWatch website (https://cropwatch.unl.edu/corn-stalk-rots-2018) or in this online publication: http://extensionpublications.unl.edu/assets/pdf/ec1898.pdf. If you conduct either the Push or Pinch test and determine that over 10% of the plants tested had compromised stalks, you may want to know “what are my options at this point of the growing season?” Unfortunately, the answer to this question is, not much. The best thing for you to do at this point is make a note of any stalk rot damage, write down pertinent information to that field (i.e. hybrid, planting population, hail/wind damage, disease pressure this year, etc.), prioritize that field when you start harvesting, and talk to your seed dealer about hybrid selection for next year to help reduce stalk rot pressure in the future. If you are still unsure if you have stalk rots in your field after conducting the Push or Pinch test, or you wish to get an accurate diagnosis, send whole plant samples to the Plant and Pest Diagnostic Clinic in Lincoln for accurate confirmation.

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