What’s going on in Ag? It has been a trying year for producers, with delayed planting, and record rainfall through the summer, growing conditions have been stressful. Stressful growing conditions can lead to poor plant health and to poor stalk quality later in the growing season. Stock rot diseases cause about 5 percent yield loss yearly, but can exceed 10 to 20 percent.
Unfortunately, many corn plants across Nebraska are showing poor stalk quality, up to 90 percent of the fields surveyed recently in our neighboring county Platte. Poor stalk quality can lead to stalk lodging, breakage, leading to harvest difficulties. Ears lost due to lodged corn may also create volunteer corn issues next year in the field.
It may be a good idea to scout fields to determine which ones may need to be harvested first or earlier to avoid losses due to lodged corn. You can do a push or pinch test to determine the severity of stock rot/weakness within your own field. This can be done by walking through the field and randomly select a minimum of 100 plants, push the plant tops away from you approximately 30 degrees from vertical. Alternately, you can use a pinch test where you pinch the internodes of the lower stalk between your thumb and first finger. If the plants do not snap back to vertical when released or the stalk is crushed when pinched, the stalk may have been compromised by stalk rot disease. If more than 10 percent of plants exhibit stalk rot symptoms, it is recommended to harvest effected fields first to reduce the chance of plants lodging prior to harvest.
There are several fungi that can cause weakening of the corn stalk within Nebraska. Physoderma brown spot caused by a fungi does not cause a true stalk rot disease, however spores can accumulate and infect nodes. This infection weakens the nodes causing them to become bridle and snap when pushed. This fungi causes a dark discolored stalk rind with healthy interior tissue. Anthracnose stalk rot was wide spread in Nebraska this year, the pathogen creates dark, black splotch lesions visible on the outer stalk. When this disease becomes systemic, a top dieback can occur in nodes above the ear, this was a common occurs this growing season. Another common stalk disease here in Nebraska is Fusarium stalk rot. Stalks may be softened and have loose strands of vascular bundles inside. It is common to see discoloration inside the stalk from white, salmon, to light pink. Gibberella stalk rot, the last of the common fungi we see causing stalk rot here in Nebraska, can cause ark streaks on the lower internodes of the stalks. Inside the stalk will be dark pink to red discoloration with this disease.
Unfortunately, there is nothing that can be done at this point in the season to stop stalk rot, as affected stalks will continue to degrade over time, thus weakening them. You can potentially minimize your losses by identifying which fields have the highest percent of stalk rot and adjust harvesting plans in hopes of harvesting them before significant lodging occurs within the field. Some seed companies provide a few stalk rot disease ratings for their hybrids, this might be helpful in selecting hybrids for fields with chronic stalk rot issues in the future.
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For updated information on crops in Nebraska, please visit UNL CropWatch at https://cropwatch.unl.edu/. #NebraskaStrong
• Nebraska Farm Hotline/Rural Response Hotline: 800-464-0258
• Nebraska Family Helpline: 888-866-8660
If you have any questions, please contact me at 1-402-367-7410 or by email at Melissa.Bartels@unl.edu.