Update from the Field: Ear it Comes Again
Posted by Dave Dyson, Agronomist on September 04, 2018
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Last year I wrote an article named “Ear Comes Trouble” after much of the Corn Belt saw an increase in ear rots. The huge amount of ear rot last year helped lay down a healthy amount of inoculum that survived and spread to this year’s corn crop. This year’s dichotomy of weather has provided the perfect storm for ear diseases. Ear fungus reproduce and spread when we have a dry spell prior to pollination, followed by wet conditions at the end of pollination—which is exactly how this year played out.
Additionally, there is a phenomenon growers have been asking about, and that I have seen at the Walton Crop Plot, which will exacerbate the ear rot problem this year: the husk seems to be shorter than the ear (figure 1 and figure 2). Bob Nielson from Purdue recently wrote about this phenomenon and I suggest reading his article published in August, “Short Husks & Exposed Ears”. He theorizes the husks were stunted by the dry weather in July, while the wet weather that followed encouraged normal ear elongation. No matter the reason this phenomenon is occurring, the results are that the tips of the ears are exposing kernels to the weather, birds, and insects. This can only have one end result: ear rot! Two major fungi that we need to be on the lookout for while scouting this fall are Gibberella ear rot and Diplodia ear rot.
Figure 1: This picture shows an ear of corn with exposed kernels because the ear has outgrown the husk. Gibberella ear rot is starting to take hold at the tip of this ear. This picture was taken by Keith Heuring at the Walton Crop Plot in 2018.
Figure 2: This picture shows how the ear has outgrown the husk, leaving the ear exposed to weather, birds, and insects. This picture was taken outside of Bunker Hill, IN in 2018.
Gibberella ear rot presents as a pink mold that first appears at the tip of the ear. Pink cotton candy is a good description of this fungus. Far from a sugary carnival snack, the Gibberella fungus not only degrades the quality of the grain it’s living on, it can also produce vomitoxin and other mycotoxins that can harm or kill livestock. Diplodia ear rot produces a white or grey mold on the ear. This fungus usually first appears at the base of the ear and will move up the ear as the fungus progresses. Diplodia will not produce any toxins but affected ears will have lower test weight, and more cobs and kernels will be ground up during the combine shelling operation, resulting in higher levels of broken corn and foreign material. The fungus that cause Gibberella and Diplodia both overwinter on corn debris and are the source of infection for the following year.
In conclusion, there are three critical factors necessary for disease to develop: pathogen, host, and environmental conditions. We have had two big ear rot years (2017 and 2018) and the pathogens will overwinter by using the corn residue as a host. Applying a combination of UltraMate® LQ and 28% UAN Solution will help reduce the corn stalk residue, therefore reducing the host for the fungus. Contact your sales representative or a member of The Andersons agronomy team to learn more about these products and proper application.
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Dave Dyson is a regional agronomist for The Andersons’ Farm Centers which are located throughout Ohio, Michigan, and Indiana. He is an Indiana native and grew up on a dairy farm in Miami County. A graduate of Purdue University with a degree in Crop & Soil Science, Dave has a deep knowledge of various agronomic topics and is committed to helping growers improve their crops. If you have any questions, Dave can be reached at david_dyson@andersonsinc.com.
