Cornmeal myth busted

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 nurture 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?)

(Another footnote: I discussed this myth more in 2012. Be sure to check this link out too.)

UPDATE: Since this is a myth that refuses to die, I’ve published a peer-reviewed fact sheet on the topic. Feel free to pass on to others.

Soap and Deer

Short post today — Linda appears to have transmitted her illness electronically over a couple of thousand miles — Thanks Linda!

I was reminded yesterday that it’s almost time for gardeners to start worrying about winter deer damage. With that in mind I thought I’d share with you my favorite research article on the subject.  It’s a little paper by Michael Fargione and Michael Richmond and published about 18 years ago.  You can find it here.

This paper attempts to establish how repellent bars of soap are to deer and comes up with some very interesting conclusions.  The first thing you should know is that no one type of soap appears to be better than another.  The second thing you should know is that soap does appear to stop deer from feeding around the soap — but the best you can hope for is a radius of protection of about a meter from the bar of soap itself — Can you imagine what that would look like if you were trying to protect the lower limbs of a large tree?  And finally, bar soap appears to attract voles.  Based on my reading, and my limited experience, I’ve found that almost everything that people say repels deer does repel deer — human hair, peeing around a tree, predator urine, dried blood — the issue is how long these repellents stay effective and how effective they are when the deer get really hungry.  The most effective commercial deer repellents tend to have “putrescent egg solids” in then (rotten eggs) — I once had a graduate student who needed to protect some hazelnuts from deer and she found that a mixture of a few eggs (2-4) mixed in a quart of water and sprayed onto the trees worked pretty well — and no, the eggs weren’t rotten.  This mixture should be sprayed about once every two weeks if possible.

Compost Tea? How About Compost Pee!

My news tab in Firefox is the BBC “latest headlines” page. It’s a great place to get pretty darn unbiased news plus the U.K. equivalent of “News of the Weird”.  SO, relative to our ongoing discussion of composting…here’s a story ripped directly from the BBC headlines. Follow the link for a video (interview, that is).

Disclaimerage: I nor any of the other Garden Professors endorse this activity, nor any claims as to its usefulness, scientific relevancy, harrumph harrumph, etc,. etc,. etc. We do, however, fully endorse garden-related humor!

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Pee To Help Make Your Garden Grow

Gardeners at a National Trust property in Cambridgeshire are urging people to relieve themselves outdoors to help gardens grow greener.

A three-metre long “pee bale” has been installed at Wimpole Hall.

Head gardener Philip Whaites is urging his male colleagues to pee on the straw bale to activate the composting process on the estate’s compost heap.

He said the “pee bale” is only in use out of visitor hours, since “we don’t want to scare the public”.

He said: “For eight weeks now, male members of our garden and estate teams have been using the outdoor straw bale when nature calls. The pee bale is excellent matter to add to our compost heap to stimulate the composting process; and with over 400 acres of gardens and parkland to utilise compost, we need all the help we can get.

“There are obvious logistical benefits to limiting it to male members of the team, but also male pee is preferable to women’s, as the male stuff is apparently less acidic.”

By the end of the year, it was calculated that the 10 men from the 70-strong garden and estates team will make more 1,000 individual trips to the pee bale, contributing towards the compost for the estate. The estate said it will have saved up to 30% of its daily water use by not having to flush the loo so many times.

Rosemary Hooper, Wimpole estate’s in-house master composter, said: “Most people can compost in some way in their own gardens. Peeing on a compost heap activates the composting process, helps to produce a ready supply of lovely organic matter to add back to the garden.

“Adding a little pee just helps get it all going; it’s totally safe and a bit of fun too.”

Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/uk_news/england/cambridgeshire/8357134.stm

Published: 2009/11/13 00:40:21 GMT
© BBC MMIX

 

Slugs and Beer: Not So Fast, My Friend…

[To those new to our blog, there are many past posts of scientifically-proven garden advice and research results…so pardon if we slip off the wagon just briefly.]

In response to the previous post:
Dr. Gillman, I’m simply shocked at your sloppy “materials and methods”.
What is that, a Frisbee? And you drink a beer called Moose Drool? Sounds intriguing, but probably too hoppy. No wonder the slugs were simply mocking your feeble attempts at attracting them.

BEHOLD the well-researched and insightful slug trap:

One 12″ plastic pot saucer + 10 oz. Pabst Blue Ribbon = 28 slugs in one night.

Not unlike college students, results indicate there’s obviously no accounting for the slug’s taste (or lack thereof) in beer. Hmmm…that gives me an idea for a grant proposal…

Slugs and Beer

Around my home I have gravel and hostas.  Just perfect, as you might imagine, for lots of slug damage.  This is where I do my work on slug remedies.  And there are lots of remedies for slugs!  One of the oldest of these remedies is beer.  Almost any beer will be adequate (including alcohol free), but generally the darker the beer the better.  When I first started testing different cures for slugs about five years ago one of the first ones that I looked at was beer.  And when I first tried it…..well, see for yourself.

This is the way that I set up my first beer trap (for this test).  There’s fine sand all the way around the trap and the trap is filled with Moose Drool (a nice beer — Suzanne, my wife — was actually a little irritated that I wasted a good Moose Drool when we had a Bud Light in the fridge — But I was only thirsty for half a beer when I set it out….and I don’t like Bud Light)

I set this trap up around 8 o’clock on a nice warm summer evening, the idea being that the next morning I could go out and see how many slugs approached the beer (by looking at the sand) and then see how many slugs the beer actually caught.

As you can see below we had quite a few slugs approach the beer (By my count about twenty).  And guess how many dead slugs were in that beer?

If you guessed 20…you’d be wrong!  There were no slugs in that beer.  Why?  Because this is a poorly designed slug trap!  slug traps are best when they are made with something like a mason jar and that jar is buried up to the lip of the jar in soil.  Then the jar should be filled up to within about an inch of the top with beer.  If you fill it higher the slug will be able to just reach his head in and drink.  In fact, after I set this trap out, I spent much of the evening watching slugs do just that — it was actually a little like watching old episodes of Cheers!  I had names for the slugs and everything (like Norm and Frazier and that mailman guy whose name I can’t remember now…).

So slug traps are good — but only if they’re set up right!