60% of the corn crop had been harvested by last weekend, along with 75% of the soybeans. That may be well and good for this point in the year, but consider the fact that 40% of the corn remains in the field along with 25% of the soybeans, and the western and northern sectors of the Cornbelt report continuing rain, water standing in the field, and muddy harvest conditions. That does not bode well for crop quality.

The crop in the field represents 5.3 billion bushels of corn and 650 million bushels of soybeans when you apply those harvest estimates to the size of the crop USDA projects for the 2007 harvest. Some of those bushels are in good shape and are coming out of the field a bit slow because not every farmer can harvest120 acres a day with the equipment he has. But many of those bushels are in varying degrees of peril because of the weather. Iowa is one of those spots where agronomists are expressing concerns about the quality of the crop.

USDA said 18% of the unharvested Iowa crop is either moderately or heavily lodged. And the agronomists at Iowa State say there is little more that is discouraging than to have the crop go down in fields which are too wet to harvest, “Flooded corn will not likely stand for much longer, which will predispose the ears to an increased chance of mold infections.” Upright ears are receptacles for water and grain in a warm most husk will begin to germinate.

The Iowa State Plant Diagnostic Clinic reports samples of stalks that have changed color and are coated with a blackish soot. Specialists diagnosed it as a common decay fungus found on dead organic matter, as well as a second fungus which is feeding on the stalks and will likely increase stalk degradation.

The high moisture conditions will favor fungi that cause ear and stalk rots, and cause mycotoxin contamination. The specialists urge farmers to harvest the corn as quickly as possible because the longer it stays in the field the greater the chance of toxin production, such as vomitoxin and fumonisin. They suggest combines be set to minimize kernel damage, since damaged kernels enhance contamination. The grain should be dried to less than 15% moisture and cooled to less than 45 degrees as quickly as possible to reduce toxin production. If there are potential mycotoxin problems, crop insurance agents should be alerted. Beware that any adjustments must be made on standing corn and cannot be made if it is in the bin.

Elevator managers have already found mold damage exceeding 5%, compared to 2% in normal years. Such damage reduces storage life. Field damaged corn should not be mixed with good grain, which includes leaving corn standing in ponded areas or where it had been on the ground or frost damaged. It should be stored separately and managed closely. Iowa State specialists say field damaged corn will not store beyond winter months, and should be kept 1-2 percentage points drier than normal grain.

If you have been able to harvest damaged grain and are drying and cooling it in a bin, an end user such as an ethanol plant will likely be rather strict on grading since it reduces the quality of its products. Disputed results can be sent to USDA as an appeal, but that takes additional time and expense. Toxins can triple and quadruple in content in distillers dried grains, and ethanol plants are reportedly running tests on corn that is particularly low in test weight.

If good grain has been mixed with grain that has germinated, pre-cleaning can eliminate much of the problem and raise the value of the good grain. Similarly, kernels high in mold content can be removed with the help of air separation, but the Iowa State specialists say that may not reduce the mycotoxin levels to a safe point.

Mycotoxins are dangerous to livestock, particularly dairy cattle, so any damaged grain should be tested before being fed to livestock. Having out of condition corn is one issue, but a sick herd of livestock is another. And fumonisin has been found in many of the higher rainfall areas.

Popcorn and other food grade corn should be treated seriously, but with the higher value of those crops, cleaning is an affordable exercise that is recommended.

Summary:
Thousands of farmers around the Cornbelt share a common concern about deterioration of their crops which are still standing in wet fields which harvest has been halted by wet and muddy conditions. Corn that is exposed to wet conditions is susceptible to various molds and mycotoxins that will reduce the value of the grain to both ethanol plants and livestock feeders. The crop should be harvested as quickly as possible, with additional moisture and temperature management, but damaged grain should not be mixed with high quality grain. Procedures are available to screen out kernels that are preparing to germinate or are moldy and that will raise the value of the grain.