Gotten this advice here a few times, so I thought this link was worth reading...

https://sharepoint.cahnrs.wsu.edu/blogs/urbanhort/archive/2010/06/30/cornmeal-myth-busted.aspx

quote:

---

Cornmeal myth busted
Posted by Linda Chalker-Scott

As my colleague Fred Hoffman says, the horticultural silly season is upon us. This week I heard from one of our European readers, questioning the use of cornmeal as a fungicide. He referenced an online article entitled "Cornmeal has powerful fungicidal properties in the garden." He hadn't been able to find any reliable information and thought it might make a good topic for our blog. So Johannes, this rant's for you!

If you've followed the link to column in question, you'll see that the original "research" is attributed to one of Texas A&M's research stations in Stephenville, TX. But it's not really research - it's just an observation on what happens when you don't plant the same crop two years in a row; in this case, rotating corn and peanuts reduces peanut pathogens. This is hardly news - it's one of the reasons agricultural scientists recommend crop rotation as part of an IPM program. And have for decades.

Then we're referred to "further research" (at an undisclosed location) where cornmeal was shown to contain "beneficial organisms." Well, no, cornmeal doesn't contain organisms, beneficial or otherwise. Microbes can grow on cornmeal, and in fact cornmeal agar is commonly used in labs as a growth medium for many species of fungi. And has been for decades.

Nevertheless, we're informed that a gardening personality has "continued the study and finds cornmeal effective on most everything from turf grass to black spot on roses." This is directly refuted by Dr. Jerry Parsons, who by happy coincidence is an extension faculty specialist at Texas A&M. His informative (and hilarious) column on brown spots in lawns states "Lately there have been claims made that corn meal and a garlic extract is effective. This is absolutely false! Everyone trying to do the "environmentally friendly-to-a-fault" thing have been wasting their money. They would have been better off making corn bread and using their garlic for cooking purposes!"

Dr. Parsons continues: "Let me explain how these University tests and recommendations have been misrepresented in a desperate attempt to find an organic fungicide. The corn meal was investigated by a Texas A&M pathologist as a way to produce parasitic fungi used to control a fungus which occurs on peanuts." (This directly relates to my earlier point that cornmeal agar has a long history of use in fungal culture.)

It boils down to this: if you have a healthy soil, it will probably contain diverse populations of beneficial microbes, including those that control pathogenic fungi. You don't need to add cornmeal - it's simply an expensive form of organic material.  So you can ignore the directions in the article on how to incorporate cornmeal into the soil, or make "cornmeal juice" to spray on "susceptible plants."   Just nuture your soil with (repeat after me) a thick layer of coarse organic mulch.

(As a footnote, let me say how annoying it is when gardening personalities grant themselves advanced degrees or certifications in their titles.  C'mon folks - if your information is so great, do you really need to pretend you’re someone else?)

---

Chalker-Scott has a web page devoted to myths.
www.puyallup.wsu.edu/~Linda%20Chalker-Scott/Horticultural%20Myths_files/index.html

She sometimes paints with a rather broad brush, but the info is generally good. In this case, building a good soil is what is important, and corn meal may contribute to that, but its by far a less effective method than composting and mulching, for instance.

The stab in the last paragraph is undoubtedly referring to the "Dirt Doctor" (a landscaper) out of Dallas. He has built a snake oil empire and often recommends repeated applications of all sorts of 'organic' products, most of which he sells. There are safe ways to do things more effectively than many of the anecdotal methods he encourages.

I thought corn gluten meal was primarily used as a pre-emergent herbicide? or am I getting cornmeal and corn gluten meal confused?

Corn gluten meal is the protein portion. It has been researched extensively in Iowa. www.hort.iastate.edu/gluten/

The soils and rainfall patterns in TX make it less effective as a preemergent herbicide here (and in Oklahoma). I would say properly applied it is less than 50% effective in TX. It is expensive at the recommended application rate of 20 lb per 1000 sf.

strings,

Cornmeal has been touted as an organic treatment for fungus while corn gluten has been touted as an organic pre-emergent herbicide.

This is the last year I will ever use corn gluten meal as a pre-emergent weed control. It just doesn't work that effectively. I've been putting it on my st. augustine/bermuda mixed lawn for the past 4 years (have kids and pets and the wife wants organic) I did my own "test" this year. In Feb. put down CGM did regular watering, waited 2 weeks and put down some bermuda seed on some bare spots that I had treated.... Bermuda is doing just fine now.

Back to the chemical weed & feed from now own. Used Scotts back in late May, anyone know of a better W&F?

i use corn meal as a fire ant killer. cake that stuff on the mound and it works great.

Corn meal will relocate fire ants. If you want an organic killer, use spinosad.

There is no good weed and feed because the weed killer part of most all of these products including Scotts is atrazine. Assuming you don't care about the environmental impacts of atrazine, you should care about how it weakens the roots of trees and shrubs in the area it is applied.

Also, usually you don't need to weed and feed at the same time. Use a preemergent in the fall and spring. Don't fertilize St Augustine now, wait until Sept.

Sprinkle grits on fire ant mound, they eat it and then it swells up and "pop" goes the fire ant!

Hey I was told this by a real smart person. Must be true.