Cornmeal Has Powerful Fungicidal Properties in the Garden
Using Cornmeal as an Organic Fungicide
By Marie Iannotti, gardening.About.com
Who would have thought that something as seemingly innocuous as cornmeal would have such potent fungicidal properties? Researchers at Texas A&M Research Station in Stephenville, TX, noticed that a peanut crop planted following a crop of corn didn’t suffer the usual fungus diseases. Further research showed that cornmeal contained beneficial organisms that were at least as effective as common chemical fungicides. Somehow cornmeal is able to attract a member of the Trichoderma fungus family, which is a good fungus that kills off disease causing fungi in a matter of weeks.
Howard Garrett, the Dirt Doctor, has continued the study and finds cornmeal effective on most everything from turf grass to black spot on roses. Furthermore, since it is entirely organic, it can be used on edible crops.
How To Apply
Dry: Work 2 pounds of cornmeal into the soil for every 100 square feet. Water well, to activate the fungus killing properties. One application per season is usually sufficient, but repeat applications won’t hurt anything.
Spray: What’s called ‘cornmeal juice’ can be made by soaking 1 cup of cornmeal in 1 gallon of water overnight. Strain the liquid and use as a spray on susceptible plants.
Any type of cornmeal can be used as a fungicide.
Cornmeal vs. Horticultural Cornmeal vs. Corn Gluten
- Food grade cornmeal, found in grocery stores, will work just fine, but it is more expensive and comes in smaller quantities than horticultural cornmeal.
- Horticultural cornmeal has not been stored under the stricter guidelines required for food grade cornmeal. Hort cornmeal is general used for livestock feed. It too will work just fine as a fungicide and it comes in bulk.
***Corn Gluten should not be used as a fungicide. Corn Gluten is cornmeal that has been processed to have a higher protein content. Iowa State researchers discovered that cornmeal gluten can inhibit seed germination. It is now used as a pre-emergent weed killer. That’s a great tip, but don’t confuse corn gluten with the fungicidal properties of corn meal.
A final bonus, cornmeal also appears to be a source of nutrients for the soil.
Per the Dirt Doctor:
Cornmeal has become one of the staple products that I talk about every day as I’m sure you know but it is confusing. The confusion comes in because there is grocery store cornmeal, horticultural cornmeal, whole ground cornmeal and corn gluten meal.
The research on cornmeal was done by the Texas A&M Research Station in Stephenville. Dr. Joe McFarland headed that work before his retirement. The discovery of cornmeal’s fungal disease control came about by noticing the peanut crops. Under research observation at the research center these crops didn’t have fungal diseases when they followed the corn planting in rotation. Lab tests related to that later discovered the beneficial organisms in cornmeal were as effective or more than chemical fungicides at shutting down fungal diseases. That’s why we now recommend it for use on brown patch in St. Augustine grass, damping off in seedlings, black spot on roses and many other fungal diseases. Dr. Nick Christian’s stuff at Iowa State University discovered the use of corn gluten meal for use as a natural weed and feed. Time to put it out right now before weed seed germination, at 15-20 lbs. per 1,000 square feet.