According to wikipedia there
are molecular mechanisms within copper that can control a wide range of
molds, algae, fungi, and microbes.
We've been cutting off new
tomato flowers to divert energy to fruit and I thought it might be a
good time to try an old wives tale I heard down at the hardware store a
few years ago.
If it slows down the blight
even a little it'll be worth the effort.
Jami --- We'll be sure to post a followup. I suspect this penny trick would be most effective if used early in the season before blight hits the patch.
Wilder Family --- Excellent point! Mark should probably go digging for an older penny --- I didn't realize modern pennies had no copper at all in them.
Copper is a well-known biocide, and was used as such even before the concept of bacteria and viruses was known. E.g. water transported or kept in copper vessels didn't develop a slimy layer on the inside of the container.
But is is not just copper. Its alloys can have the same antimicrobial properties, but to a somewhat lesser degree. What is really cool is that copper also works well against some viruses and fungi.
If you can't find copper pennies, use red copper water pipe. I'm not sure how common that is in the US; here most houses have copper freshwater pipes.
Based on this, I had another idea to protect your tomatoes; IIRC, you seem to have observed that the lower leaves are blighted first.
To protect your tomato plants (after you've tied them up) I propose you put some fine copper(-plated) mesh around the plant, parallel to the ground, a couple of inches up. The mesh should intercept dust particles as the rain splashes them up, while the copper wreaks havoc on bacteria and possibly spores that touch it. It also keeps the leaves off the ground.
Roland --- Great ideas, as usual. By the way, I did a few seconds of research and found out that even modern pennies have a very thin coating of copper, which I'll bet is sufficient for the use Mark is putting them to. And I think we have some copper water pipe in the barn, too.
I wonder if it would work to have a circle of copper-plated mesh on little feet that you put a few inches above the mulch? I like your idea of focusing on the real problem, which is splashing up from the ground. I don't want to put the copper directly on the ground, though, because it could kill the important soil microorganisms. I'll bet there's a microbusiness product there if anyone wanted to test it out....
Angela --- Yep, that's what I eventually learned after I did some research. Lots of fascinating information out there on the internet about copper content of pennies!
Anonymous --- Spraying on copper is the mainstream "organic" way to prevent blight, but it's a very strong treatment that I don't really approve of. The copper ends up in the soil, where it kills essential soil microorganisms and can also build up to problematic levels for plants after a few years. That's why we work around the blight rather than spraying copper. Although I'm not so sure Mark's technique will do any good, it will also have the benefit of doing no evil since the copper is unlikely to end up in the soil in more than miniscule quantities.
Since metallic copper does not dissolve in water, I don't think placing copper mesh directly onto the ground will do much harm (as opposed to the soluble copper(II) compounds that are usually sprayed on plants)
But putting the copper aboveground just to be sure was exactly what I had in mind;
This should put the copper mesh 2" above ground. You could even fill the space under this contraption with straw as an extra mulch to keep the competition out.
Hmm, I can't seem to find a composition for the stuf-fit, other than that it of composed out of "various metals". And it looks like its braided rather than woven, so it might come apart when you cut it open to lay it flat.
The more expensive stuff is 90% copper with 10% zinc, so technically a brass. Presumably to keep it from oxidizing quickly. That seems like a good idea.
I would go for a relatively fine woven mesh, say 20 wires/inch, like e.g. this one. I think you could find stuff like that at an arts & crafts store, or at a place that sells electronics (as faraday shielding).
Bottom line: go for a high copper content (but probably not pure copper; brass corrodes less quickly AFAIK), and a relatively fine mesh.
Of course the way to learn the most is to do a carefully controlled experiment with different meshes, but that almost goes without saying, I guess.
For more info, read up on "design of experiments" (DOE).
Roland --- Our terrain is so varied that if I wanted to get any semi-definitive results, we'd have to stick to one experimental treatment and a control, alternated throughout the garden beds. That's why I was wondering which type of material you recommended --- sounds like the twpinc one might be our best bet.
Now lets see if I remember I wanted to try this come next April....
MamaHomesteader --- There was a marble factory close to where my father grew up, and my memories of visiting my grandmother involve a lot of digging up marbles. But maybe your yard just housed marble-playing kids before you?
Roland --- Good idea.
Interesting, never heard of this before! I've got some scraps of 2-conductor electrical wire (the stuff that is used to wire up your outlets, etc); I'm thinking the solid copper conductor, snipped off with a wire cutters, will have a nice pointy end that could be easily embedded into a stalk - I think I'll try this next year!
I friend sent me this link:
http://www.lenntech.com/periodic/elements/cu.htm
Any comments?
Glenda --- It might take a lot of pennies to protect a whole tree. But Roland's suggestion in the comments might work --- some kind of copper netting.
Anonymous --- If you give it a try, I hope you'll come back and tell us about it!
Diane --- Glad we could help.
Carol --- That's related to the reason I'm not a fan of the copper sprays that are allowed in organic production. The benefit of using something like a penny instead is that the copper shouldn't end up in your food (and in the soil) --- the metal stays put where you place it. Of course, the question is, does it do any good?
thanks people our growing season is just beginning and i'm growing in a new area, CBD auckland NZ, the neighbours are not gardeners, this blog has been sent by the vege Gods.
Mauriora = health and wellness to you
Silver --- That does sound like a good alternative to experiment with.
Therese --- So glad to help you find an online community! We are definitely passionate about gardening here. Love your "vege Gods" comment.
The copper penny or wire is better than sprayed copper. As the copper oxidizes from the penny or wire the rain or water will leach it into the soil. There is less chance of soil contamination from copper this way. But the better way is building up the lacto-bacteria by adding milk or milk products and then you get calcium too.
When I plant my tomatoes I add two tablespoons of powdered milk, green sand, bone meal and epsom salt. Later if there is any sign of blight keep sprinkling powdered milk on and around the plants. It promotes the lacto-bacteria that attacks the blight.
One of the best things you can do though is to stake the plants and keep the bottom leaves trimmed up so that they don't touch the ground and are high enough so that soil doesn't splash up on them. The lower leaves are not a big sacrifice for the plants.
powdered milk is great for tomato's. It puts calcium in the soil. Here in Texas we have some intense heat in the summer, I put my tomato's out in February same time you cut back your roses,2-14. I get a large amount of tomato's in the spring, when summer comes I water in the powdered milk, because tomato's need extra calcium when they are stressed by the heat, they kind of go dormant in the summer, then when it cools down I get another flush of tomato's until we get a frost if I don't cover them, I will lose them, but they grow almost all year here. Another good thing is milk of magnesia, it puts magnesium back into your soil, which is what is lacking if your leaves start to yellow, also works on roses. I know this because I am a Master Gardener here in Texas. So these things do work.
To respond to the comment about using black plastic to prevent blight, this is true and effective to prevent soil borne blight. But late blight comes with the rains, it can be carried on the winds so you need the powdered milk solution or the copper solution.
Another possibility is using compost tea. Compost tea has a plethora of bacteria and some of them fight blight, plus compost tea is super for the soil both nutrient wise and adding beneficial bacteria to the soil.
I have also seen people using copper wire strung along the top of the stakes or tomato cages, to allow copper to be gradually oxidized and released into the soil. This way only minute quantities are released into the environment, but enough to be effective.
Thanks to the power of Facebook I got to read this article and am fascinated.
Perhaps by inserting the penny, or other copper item, in the main stem of the plant, the effect could be dispersed throughout the plant allowing fast and efficient protection without too much investment. Will be great to read updates through the season, though hopefully it won't be a blight affected year. Thanks for documenting.
The contributors thus far have taken two positions on copper- that it doesn't dissolve in water, and that it will travel through the tomato plant and inhibit blight. It can only do that if it is at least a little soluble in water.
I see a lot of speculation, but not so many that have said that it worked for them. Are there more people who have tried it, maybe on some of their plants and not on others, and what happened?
Since 1983, US pennies are made from zinc, which is only copper-plated. So the copper content is only 2.5%.
Pure copper itself doesn't dissolve in water. It does slowly oxidise in water containing oxygen and carbon dioxide, which leads to copper ions on the surface that readily dissolve. The mechanism is explained in this paper. This will dissolve up 30-50 mg/m2/day depending on the oxygen content of the water. In other words, it will take a year for at most 280 grains of copper to dissolve from 10 square feet of copper!
I actually bought some of these copper scouring pads in order to do this. I am planning to cut the pads and wrap a few strands around the plants. Will try the powdered milk too. Blight has been a huge problem in our area. http://www.yaysave.com/catalogsearch/result/index/?cat=1215&q=copper+scouring+pads
copper will do some thing that is sure. my antenna for my radio hung over the roof of my house, and directly under the antenna there was no fungus growing, but off to each side the roof was black with it now the shingels looked just like new where the antenna hung over it I will try to see if some copper wire will help on tomato blight .
I just came in from placing pennies in my tomatoes. While the blight hasn't been as bad as previous years, it still has affected my tomatoes by "creeping" up the vines after lower tomatoes have been picked. my vines are over 7 ft. tall and producing very well. This is first year that I haven't had blossom end rot and I attribute that to the amendments I used all season so far - a boron (borax), Magnesium (Epsom salts), and Dolomite lime mixture I read about online. I have exceptional results in my raised beds and Earth Boxes! However, my tomato vines are getting "leggy" as I keep getting rid of leaves and limbs showing the blight. I still have huge tomatoes on my Beefsteak and Mortgage Buster tomatoes. I'm going to try the powdered milk in addition to the pennies and I'll try to let you all know how it goes. I'm also going to put a penny near the roots of my Roma tomatoes that are just beginning to bear fruit. Thanks to everyone for their input here. Much appreciated.
I've just put Pennies on half (15 plants), my Mortgage Lifter tomato plants and wrapped copper speaker wire on the other 15 plants. I wrapped the copper speaker wire around the stalk of the plants. I'll post in 30 days and let ya'll know which method worked best! Craig
i live in KY anf have 144 better boy tomato plants in my garden. I have a plot in a community garden area. Yesterday as I was starting to tie up my plants I noticed some little black bugs on a couple Plants and some plants also have some black markings on the stems and leaves. I just stayed today with a mix of seven dust and water to get rid of the black bugs. I'm also wondering if the marks on the leaves and stems are from those as well or if it's the beginning stages of blight. Last year I struggled a lot with blight and I am trying to prevent it this year because my yield was low. Any ideas as to what is going on? I also have a couple of pics that I've when on my phone of both things if there is a way to load those to this blog any help is appreciated!
I have been thinking about adding pennies to my garden for years. I always held off because I did not know if the metal would somehow get into the food. I am encouraged to learn that the copper only dissoves very slowly.
I had heard of using milk for powdery mold mildew, but never for blight. Powdered milk will be a much easier application. I have used egg shells with excellent results for preventing blossom end rot.
Newer pennies contain zinc - isn't zinc also anti fungal? I use a barrel and hand water, I think I will throw a few pennies into the barrel. Next year, a penny in every hole - if it works, that is a real cheap fix! It will also give future gardeners something interesting to find when I am long gone!
I would be real interested to find out how earlier poster's made out with different methods.