Dave Nanda reported at the end of June that this might be the year for gray leaf spot. That was after five days above 90 degrees in the east-central Corn Belt, with high humidity. A month later he said forget it- the weather had cooled and disease development had tapered off. He didn't even end up recommending that fungicide be applied in that field.
And while that was the right call, the weather changed once again, and gray leaf spot became an issue in other areas before the season ended. Because August was so cool, northern corn leaf blight also took off. Nanda reported seeing it widespread din many ro the areas where he traveled late in the season. Some of these same conditions also set up serious problems with ear rots that are being discovered as harvest begins to pick up steam across the Corn Belt.
In the end, gray leaf spot and northern corn leaf blight helped shut down some fields. If the corn was planted late and the grain was still relatively immature, it was one of the factors that is resulting in low test weight, notes Bob Nielsen, a Purdue University Corn specialist, writing on his Web site, www.kingcorn.org.
Other factors for low test weight being reported in some areas include the fact that corn is wet, drought, believe it or not, in pockets, and premature death by other diseases or frost. The ear molds often also result in chaffy, lightweight corn since many shriveled kernels result from severe infections.
Ear molds are an issue from Ohio to Nebraska. The problem with these molds is that some also carry toxins. While aflatoxin is often the one associated with grain problems, and it typically results from corn surviving dry conditions, Vomitoxins and other substances produced by Gibberella, a pinkish mold on corn ears, can affect feed intake by livestock. If levels are high enough, reproduction can also be impacted. Swine are usually impacted first, but other species, including ruminants, aren't immune from reacting to high levels of these compounds in the feed.
The development of ear molds is again weather related, most specialists believe. The right conditions existed at the right time to allow the fungus causing these molds to develop. While there may be some differences in hybrids, the onslaught of disease overpowered may fields of a variety of brands of corn, and a wide variety of hybrids.
This season gives Nanda a platform for making a statement he believes is critical. "Companies ought to be turning breeders loose and investing in finding disease tolerant and resistant hybrids," the former plant breeder says. "We have traits now to protect against insects, but we need protection against disease as well."