Monitoring for mycotoxin-producing molds vital

myco_corn_blogWith the harvest underway, it’s important to keep a watchful eye out for mycotoxin-producing molds.

These species include Aspergillus flavus, which causes Aspergillus ear rot and produces the carcinogenic toxin aflatoxin, as well as species of Fusarium molds. These toxins can lead to production losses as grain may be rejected, as well as leading to illness in humans or animals that consume the toxin in significant quantities. Here’s a quick primer on some molds of concern and the toxins they produce.

For more information and regulatory thresholds for toxins, please see Neogen’s Mycotoxin Handbook.

Aspergillus

This mold thrives in hot and dry conditions such as those present during last summer’s drought that caused an outbreak of aflatoxin.

Aspergillus presents as an olive-green powdery mold beneath the corn husk. Although it most often is seen at the tip, it can be found throughout the ear, according to the Purdue University Extension. Although the powdery green mold is indicative of Aspergillus, results should always be confirmed via diagnostic test.

A. flavus also produces aflatoxin, a known carcinogen that also is produced by A. parasiticus. There are four main types of aflatoxin (B1, B2, G1 and G2), with aflatoxin B1 being the common and the most carcinogenic. Aflatoxin most often affects corn, peanuts, milo, cottonseed and most tree nuts. In animals, ingesting too much aflatoxin can cause chronic health problems such as liver damage, cancer, decreased egg and milk production, immune suppression and reproductive efficiency.

Ochratoxin, a suspected carcinogen, is produced by another species of Aspergillus called A. ochraceus. It also can be produced by Pencillium viridicatum, and most often is found in corn, barley, green coffee and dried fruit. Ochratoxin can affect the kidneys and reduce egg production in hens.

Fusarium

Fusarium molds are associated with several major mycotoxins, including deoxynivalenol (DON, or vomitoxin), fumonisin and zearalenone. Unlike the molds the produce aflatoxin, Fusarium tends to thrive in damp, cool weather.

It also causes Fusarium head blight in wheat, which can cause serious losses and decreases in grain quality. Typically, only the head of the grain is affected although in some cases, the neck may be as well. The spikelets will appear bleached, shriveled, and pink and/or orange mold colonies may be visible, according to Purdue.

DON most often is produced by the pink mold Fusarium graminearum, and can be present on wheat, corn, barley, ensilages and other cereal commodities. It can cause illness in livestock (hence the name vomitoxin), including nausea and vomiting, feed refusal, gastroenteritis, diarrhea, immunosuppression and blood disorders.

Fumonisin is produced by several species of Fusarium. They commonly infect corn and rice. These toxins have been associated with esophageal cancer in humans, and are of special concern in horses as even low levels can cause leukoencephalomalcia (liquefaction of the brain). Swine also are at risk as fumonisin has been shown to cause live and pancreatic lesions and attack the cardiopulmonary system causing edema. The toxin is classified as a category II-B carcinogen.

Like DON, zearalenone also primarily is produced by F. graminearum. As such, if there’s evidence of zearalenone, there is a good chance DON may also be present (or other fusarial toxins). Zearalenone is an estrogenic toxin, meaning is causes estrogenic responses in animals as well as reproductive issues such as failed pregnancies and reduced litter sizes.

T-2/HT-2 toxins also are produced by Fusarium molds. Although they are two separate toxins, T-2 toxin metabolizes to HT-2 toxin and they frequently are evaluated together. Several species, including cattle, poultry, dogs, cats and horses, are susceptible to T-2/HT-2 toxins. Symptoms of ingestion include hermorrhaging, edema, oral lesions and blood disorders and in the most severe cases, death. Poultry also can face reduced weight gain, beak lesions, motor impairment and increased susceptibility to Salmonella. In humans, T-2 toxin is the main cause of alimentary toxic aleukia.

For more information on Neogen’s mycotoxin tests, click here.

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