Corn Ear Molds Showing Up

We have seen numerous ear rots, or molds in various locations. The most prevalent one seems to be diplodia. We’ve seen some gibberella and some of what we believe to be penicillium molds (not positively identified).

Corn ear molds can develop under many different environmental conditions, but may be especially prevalent when the weather is cool and dry prior to pollination followed by ample moisture during grain fill. Ample moisture refers more to morning dews and foggy conditions than it does to overall soil moisture – in some places we are seeing ear molds even where the summer drought conditions have continued on into the fall.

Diplodia generally begins at the bottom, or butt, end of the ear, but we have found it in ear tips as well. Diplodia will be white to gray in color and may surround a few or many kernels, at time encompassing the whole ear. Kernels may be light-weight or may be damaged enough to essentially be of no nutritive value or yield significance.

Pycnidia, the black specks seen on husks, cobs, kernels etc., are the spore producing bodies and overwintering structures of diplodia. The likelihood of disease is increased in corn on corn and no-till acres.

Diplodia infected corn is often difficult to harvest and clean effectively, as the cob is affected as well as the grain. Cobs break up or are mushy, and kernels are light weight, covered with mold, etc. It is important to identify the disease and manage harvest accordingly. Clean grain as much as is possible at the combine. Dry the grain to 14% moisture to prevent secondary fungi from developing. Remove bin cores early, as diseased fines and kernels may accumulate and result in spoiled grain.

We have observed some differences in hybrid susceptibility. While no hybrid is truly resistant, it is useful to try to select hybrids with better tolerance.

One very poignant observation: wherever the western bean cutworm (WBC) has infested the ear, there is a high likelihood that mold will follow. WBC often chews a hole in the husk. That hole in the husk is often an easy conduit for fungal spores and the resulting molds. Damage has been severe in some cases. This, then, is another clear case for Herculex hybrids, as WBC will generally not damage husks and ears of Herculex traited corn, thus not giving rise to the development of ear molds from this route.

We have focused in this brief update on diplodia. Call us if you see ear rots and want to investigate further.

If you have any questions or concerns please contact:

Terry Jones CPAg, Regional Agronomist @ 419.346.7786 or


or

Rod King CCA, Regional Agronomist @ 574.596.6721 or