Aspergillis ear rot and Aflatoxin in Corn as well as other ear rots that cause mycotoxins

Aspergillus ear rot, as well as other ear rots were an issue in some areas of Illinois in 2011. Some areas experienced hot and dry weather or STRESS after silking, which are favorable conditions for Aspergillus ear rot as well as Fusarium ear rot.  Other areas, which were lucky enough to get some rain after flowering, may have had a risk of Diplodia ear rot, especially if it was a problem in previous years. In most cases, injury by birds or insects (as seen in the pictures below), allow entry of ear rot fungal pathogens.  Often times, fields that are corn on corn and have reduced tillage allow for the build up of and survival of the ear rot fungi, where it awaits for the right conditions to flourish on a injured or stressed corn crop.

Picture taken by Angela Peltier, U of I Extension Commercial Crop Educator.  Kernals infected with Aspergillus (greenish fungus) as well as Diplodia (white fungus) and possibly Fusarium (starburst pattern on kernal) are present.

Picture taken by Angela Peltier, U of I Extension Commercial Crop Educator.  Kernals infected with Aspergillus (greenish fungus) as well as Diplodia (white fungus) and possibly Fusarium (starburst pattern on kernal) are present.

Picture taken by Angela Peltier, U of I Extension Commercial Crop Educator.  Kernals infected with Aspergillus are present.

In response to this outbreak, Angela Peltier authored the following article:  Corn ear molds make an appearance in western Illinois


 Aspergillus flavus and Aspergillus parasiticus, the fungal pathogens that causes Aspergillus ear rot, produces a very, dangerous mycotoxin that is considered to be a  major carcinogen!  The FDA regulates the allowable amount of this toxin in grain for food or feed and less than 20 ppb (parts per billion) is the allowable amount of the toxin in grain intended for human consumption and immature animals. At the U of I Plant Clinic, one of the diagnostic tests that we use to detect the fungal growth of Aspergillus flavus, is put a black light over the corn ear in a dark room.  The black light will cause corn kernals infected with Aspergillus flavus to glow in the dark.

 

 Some other diagnostic techniques used to diagnose ear rots involve "plating" infected corn kernels on agar to allow the fungal ear rot pathogens to grow.  Identification can be made by spore and fungus morphology.

Aspergillus sp. are not the only fungal ear rot pathogens to produce mycotoxins in corn. For more information on Aspergillus ear rot, see the following link: http://cropdisease.cropsci.illinois.edu/corn/Aspergillusearrot.html

Other ear rots that can cause mycotoxins:

• Fusarium ear rot, often characterized by a starburst pattern on corn kernals, caused by Fusarium moniliforme, F. proliferatum, and F. subglutinans can also produce a mycotoxin called Fumonisin. For more information, see the following link: http://cropdisease.cropsci.illinois.edu/corn/Fusariumkernelandearrot.html
• Gibberella ear rot, often characterized by a reddish mold first on the ear tip, then spreads downward, caused by Gibberella zeae (=Fusarium graminearum) also produces multiple mycotoxins.  For more information, see the following link: http://cropdisease.cropsci.illinois.edu/corn/GibberellaRedearrot.html

In Illinois, to get an accurate test for the concentration of mycotoxins in grain, you can send samples to the Illinois Department of Agriculture CENTRALIA ANIMAL DISEASE LABORATORY

Please call them for further instructions and information.

For more information, contact:
Illinois Department of Agriculture
Centralia Animal Disease Laboratory
9732 Shattuc Road
Centralia, IL 62801-5858
618.532.6701
TDD: 217.524.6858
FAX: 618.532.1195

Need some information on ear rots and grain storage?
Check out this link to another 2011 article written by Dr. Suzanne Bissonnette:   Look at Your Ears-Crop, Stock and Ledger

Seed collecting, Treatments, and Storage

This weeks University of Illinois Plant Clinic blog was brought to you by:
Mike Kwiatek, University of Illinois Horticulture Student and Plant Clinic Student Worker

If you haven’t started collecting seeds yet, it may not be too late. Seed collecting is a fun pastime that provides you with plants for the following years to come, lets you share favorite varieties with friends, and saves you some money for the next season. Many home gardeners collect seed and some even participate in seed exchanges, which allow gardeners to meet and share some of their collected seeds with other gardeners. If you’re interested in participating in a seed exchange, look to community newsletters, local co-ops, and organic food stores; as they often play host to these events.

 When collecting seed, consider choosing from plants that looked their best this year.  Try to avoid collecting seeds from plants that are known to be hybrids.  Lastly, be aware, that for many plants, the plants that will grow from your collected seeds, may not look exactly like the plants that grew the previous year.

There are two main types of seeds: dry seeds and those that come from moist fruit. Vegetables such as beans and ornamental plants such as cosmos or zinnias will produce dry seeds, which can be treated for disease, dried, and stored. Seed should always be harvested when dry.  Those seeds that come from moist fruit, can be scooped out once the fruit has fully ripened, washed in a strainer, or sieved to remove any mucilage; then can be treated, dried, and stored. If dealing with squash or pumpkin seeds, a strainer alone will likely not be sufficient to remove the stringy mass that surrounds seeds.

After the collecting seed, it is very important to treat the seeds in order to reduce seedling infection or death caused by bacterial diseases like Xanthomonas and fungal diseases such as Alternaria. Seed treatments will vary by plant species. Plants like eggplant, tomato, pepper, carrot, spinach, lettuce, celery, cabbage, turnips, radishes, broccoli, and related vegetables should be treated with hot water. (See the following link for more details http://en.wikipedia.org/wiki/Cruciferous_vegetables).  Vegetables like squash, gourds, pumpkins, watermelons, asparagus, as well as flowers like zinnias, should undergo a chlorine treatment.

Hot water treatment

Place washed seed in a cotton bag, nylon bag, or wrap it in cheesecloth.  Warm the seeds for about 10 minutes in a 100F (37C) degree water.  Drop the bag into water that is 118-125 degrees Fahrenheit (47-51C) for 15-30 minutes, depending on treatment (See the following link for more details: 

http://ohioline.osu.edu/hyg-fact/3000/pdf/3085.pdf ) .  Place the bags of seed in cool water for about 5 minutes after the set period of time and then, place them on a screen or newspaper to dry.

Bleach Treatment

Make a solution of 20% bleach, 80% water, and surfactant (dish soap will be adequate). A simple way to do this is by mixing 1/4 cup bleach to 1 cup water, and then add a drop or two of dish soap to this mixture. Place the seeds in this solution for one minute and mix. Then pour this mixture through a strainer and rinse the seeds well with water. Place the seeds on newspaper or a screen and allow them to dry.

Storage

When your seeds have completely dried, place them in paper bags or envelopes, label them properly, and store them in a cool, dry place. Adding a piece of paper towel or a napkin to the envelope or bag will help ensure dryness. You may choose to store the bags in the bottom drawer of your refrigerator. If you do this, you may wish to place all envelopes or paper bags in a plastic bag with 1-2 pieces of paper towel. This will ensure that if any spills occur, your seeds will be safe.

Another helpful web Source:

http://web.extension.illinois.edu/cook/downloads/8584.pdf

Related links:

http://www.seedsavers.org/

http://www.heirloomseedswap.com/