Be Prepared For Potential Stalk Rots in Corn This Fall
Throughout the 2019 growing season, growers have faced significance issues from many different directions.
Unfortunately we need to be prepared for yet another one: stalk rots in corn.
What can lead to stalk rots? Stalk rot pathogens, such as Anthracnose and Fusarium, are always present in the environment but need certain weather and host conditions to become a widespread problem. The prolong period of wet weather that the Upper Midwest has faced in recent months is favorable for stalk infection by a variety of plant pathogens. The wet weather also favors infection because it has led to many fields being overly stressed due to a lack/loss of nitrogen, compromised root systems due to sidewall compaction, lack of tillage to bury inoculum in past residue, and general failure to thrive due to saturated conditions. Plants affected by these stressors are more likely to have weak stalks already and are much more susceptible to infection. Some hybrids may also be more genetically susceptible to certain diseases as well. Before harvest
begins, work with your Jacobsen seed representative to highlight fields that may have one or more of these risk factors and scout for stalk rots infields that you identify.
How do we scout for stalk rots? Scout regularly and use the PUSH or PINCH tests to indicate stalk issues. For PUSH – Push the plant tops away from you at a 30 degree angle. If they don’t return to vertical or they snap, they may be compromised by a stalk rot. For the PINCH test – Pinch the lower internodes of the plant. If they are crushed easily by your hand their integrity has been compromised. If 10% or more plants fail these tests consider harvesting the field early to reduce possible losses. Once you find plants that fail either of these tests it is important to cut the stalk open in order to understand exactly what disease you are looking at to help with future management decisions.
WHAT CAN YOU DO TO REDUCE THE RISK OF STALK ROTS IN THE FUTURE?
• Reduce corn stalk residue by rotating to a non-host crop or by using tillage to bury residue. Both foliar and stalk diseases over winter in the residue leading to higher pressure next season.
• Choose a more tolerant hybrid next time the field is in corn production. Many companies give disease, stalk, and stress ratings which can be put together with the help of your seed adviser to give you a more tolerant hybrid.
• Make sure to keep up fertility! Correct soil fertility is the first step towards a healthy
plant. Use soil tests to understand your current levels and fertilize accordingly.