"Over the last week I have had many reports of a gray-black to dark green mold found on corn ears in the fields throughout northeast Iowa," says Brian Lang, Iowa State University Extension field agronomist at Decorah. "This is very likely a mold called Cladosporium. It is described as a mold that infects kernels damaged by insects, hail or frost. But for that matter so do many other molds."

Cladosporium is described as a gray to black or very dark green mold with a powdery appearance, and can cause black streaks on kernels. "The good news is that it is rare for this mold to produce mycotoxins corn," says Lang. "Also, we have seen significant amounts of this mold fall off or blow off the kernels during combining. It is good to see that happening." 

* Dark green to grayish-black mold in corn. Ear and kernel photos can be seen here.

* Green to dark green mold in corn. Another mold that Lang is getting fairly frequent reports on is a green mold called Trichoderma ear rot. This mold is described as a green to darker green mold that grows on or between kernels and can cover a large amount of the entire ear. Penicillium mold would look similar, being a green to blue-green mold, but is usually more patchy and often found at the ear tip. Again, like with Cladosporium, it is rare for Trichoderma mold to produce mycotoxins corn.

* White and pink molds in corn. These molds are more commonly associated with potential mycotoxin problems. What Lang is seeing is mostly Fusariums but also Diplodia. Photos and descriptions of Fusarium, which is a white to pink mold scattered throughout the ear can be found here.

Gibberella (a type of Fusarium mold) is a white to pink mold often on the upper half to tip of the ear. Photos can be found here.

Diplodia is a white mold at the base of the ear.

Every decision that you make influences the size and scope for corn yields. From the corn hybrid you select to the seeding rate and row width you choose. Download our FREE report over Maximizing Your Corn Yield.

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How do I go about getting a test of my corn for mycotoxins?
The ISU Veterinarian Diagnostic Lab at Ames has recently simplified their procedure for sample submission and testing for molds and mycotoxins of corn grain. They have a new sample submission sheet at which is very easy to follow.

Lang gives this example:  "If I want to check for mold and mycotoxins of the four largest concerns (aflatoxin, fumonisin, vomitoxin, zearlenone) I would select Mycotoxin Screen #3. That would cost $70 for the mold ID. If any of the molds are identified, then on request the lab would run a quantitative test to determine the mycotoxin concentration. The quantitative test for each mycotoxin is in the ballpark of $35 each. You would likely want to request the quantitative testing if you plan on feeding this grain to your livestock to understand if any feeding limitations exist." He says potential feeding limitations are provided in the fact sheet.

* Collecting the sample to send to the lab with the submission form:

Sampling error or collection of a non-representative sample is often a weak link in submitting feeds or forages for analysis. General rules for grain and silage sampling are:

For a corn grain sample:
1)  Use cloth or paper packaging to maintain grain sample integrity during shipping, since plastic bags promote fungal growth.

2)  Take at 12 to 20 stream samples from a combine or grain cart.

3)  Mix the sub-samples well and obtain a one-pound composite sample.

4)  Keep in a cool dry place until shipping.  Ship the same day, and early in the week to prevent samples from sitting in the lab over the weekend.

For a corn silage sample:
1)  Obtain 8 to 12 sub-samples from the field, during the harvesting process, or from storage.

2)  Mix sub-samples well and obtain a minimum 1.5 pound composite sample.  i.e. at least a quart, but a half-gallon bag would probably work better.

3)  Place composites in a thick plastic bag or double plastic bags. Pack composites tightly and force out excess air before sealing with a good closure tab.  Make absolutely certain that the bag will not leak.  Postal businesses do not ship leaky packages and have fines associated with this.

4)  Some labs suggest that you freeze the sample, but the ISU Vet Diagnostic Lab does NOT want the samples frozen.  Just package according to directions and ship to the Lab the same day, and early in the week to prevent samples from sitting in the lab over the weekend.

Every decision that you make influences the size and scope for corn yields. From the corn hybrid you select to the seeding rate and row width you choose. Download our FREE report over Maximizing Your Corn Yield.

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There is a simple test for mold identification
The more expensive testing and steps to collect a representative sample described above is necessary to properly test for mycotoxins. However, if you just want a simple ID of the mold, a few ears could be sent to the Plant Disease Clinic for a $10 fee. The recommended procedure is:

1)  Collect a few ears with the mold on them that you want identified.

2)  Put them in a box with the husks pulled back, but included in the sample.

3)  Fill out the sample submission sheet.

4)  Enclose a $10 check as mentioned in the sample submission form.

5)  Mail to the address on the sample submission form. It is best to mail on a Monday or Tuesday.

6)  Extension offices have available pre-paid pre-addressed U.S. Post Office labels for your package(s) if you wish to stop in at the Extension office to pick this label which would cover your postage cost.

Again, this is just for disease ID. This sample will not be tested for any presence of mycotoxins.  If the mold or molds identified are ones of concern for potential mycotoxin development, you would need to follow the directions under "Testing for Mycotoxins" to determine the extent of the problem.

Questions and answers about drying, storing soybeans
Bill Wilcke, Extension ag engineer at University of Minnesota wrote a six-page piece recently covering most any question regarding drying and storing of soybeans.

And the University of Nebraska just published the following sheet with nice charts on estimating drying time for soybeans with natural aeration.

Iowa State University ag engineer and well-known grain quality specialist Charlie Hurburgh says that as a guideline, soybeans in storage tend to act about the same as corn that is 2 percentage points greater in moisture content. For example, soybeans at 16% moisture could be expected to act like corn at 18% moisture. Aeration is always recommended with all storage facilities. If storage temperatures are below about 60 degrees, soybeans at 13% moisture can usually be kept for about six months without having mold problems.

Upper Midwest resource page for 2009 late harvest information
The University of Minnesota just created a Web site organizing many of the university resources in the Upper Midwest mentioned previously in various newsletters.

Included a this site are the most critical ICM News articles from Iowa State University specialists relative to current commonly ask questions:

* 2009 Corn Quality Issues (including reference to USDA grain inspectors)

* 2009 Corn Quality Issues – Field Molds

* 2009 Corn Quality Issues – Storage Management

Every decision that you make influences the size and scope for corn yields. From the corn hybrid you select to the seeding rate and row width you choose. Download our FREE report over Maximizing Your Corn Yield.