What is Corn Smut?!? (And How to Prevent It)

6 comments by Luke Marion

Have you ever grown corn, and when you went to harvest it you were shocked, disgusted, and horrified by large black, blue, or grey growths on your corn? This is called Corn Smut! Believe it or not, it's actually edible too. Not that I would prefer it over corn, in Mexican culture, it is considered a delicacy. So what is corn smut and how can you prevent it? 

Corn smut, also known as Ustilago maydis, is a fungal disease that affects corn plants. The fungus infects the kernels of the corn, causing them to swell and form grayish-black, tumor-like structures known as galls. These galls can grow to be quite large and are filled with a black, powdery spore mass that can be spread to other plants by wind or insects.

The fungus that causes corn smut thrives in warm, humid conditions and is most common in areas with mild winters and wet summers. It can also be spread through contaminated seed, equipment, or soil.

To prevent corn smut, you should practice good crop rotation, using different fields for corn each year.  Also make sure to avoid planting in areas that have been recently affected by the disease. Using disease-free seed and ensuring proper sanitation of equipment and tools are also important steps in preventing corn smut. You can alo buy corn that has been treated with a bio-fungicide, however this is often not available for home gardeners, and when it is it is NOT organic. 

Home gardeners can also use fungicides to prevent infection with limited success. It is important to note that fungicides need to be applied at the right time and in the right amount to be effective. Applying fungicides too early or too late in the growing season, or using the wrong type of fungicide can result in ineffective control of the disease. Regardless of organic or inorganic application, studies show mixed results with application, so I would recommend not spending the time or money. 

Another preventive measure that can be taken is to remove and destroy any infected plants. This will help to reduce the amount of spores in the environment and make it less likely that the disease will spread to other plants. If you do end up getting it, maybe consider trying some! At least you won't be wasting any food. Hey... When life hands you lemons, sometimes you need to make lemonade. 

 

Grow bigger, 
Luke


6 comments


  • Carol

    I’ve never heard of any variety of corn smut being toxic, but if left too long, it gets dry and releases spores, so if you’re eating it, it should be nice and firm, and not dusty. It is a unique flavor, well worth trying. Plus, harvesting it as soon as you find it keeps it from releasing more spores. Win/win :)


  • Molly S.

    Thank you, Luke. The information I got locally was to just avoid planting corn in my garden for ten years and that should clear the smut spores in the soil. Ten years! I actually tried that and the first crop of sweetcorn after the wait was ruined by smut too. Fast forward a few more years and last year I tried your blue mini popcorn and for a test only grew a 3’ square patch of it and it did fine. So I’m sure the high quality seed had everything to do with that.


  • Susan Eaton

    I had this happen to one of my corn stalks this summer and I cut it off and threw it out. It was my first time growing corn and didn’t know what it was. Thanks for the information.


  • Pat

    Nice to know…thanks!


  • Brenda Huckeba

    Thank you for posting!!


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