Farm Notes by Miriam

Hello Folks,

Talk this time of year tends towards the tomato. From expressing adoration for those lovely red orbs to cursing the blights that befall the plants, this solanaceous super star gets a lot of attention in August. For all the glory there is a price to pay in the form of endless trellising and ubiquitous copper spray. While methods for trellising are more varied than one might think (cages, weaving, high-tensile wire, etc.), nearly every “Organic” grower I know relies on the legal use of copper to suppress blight.

Most blights that effect tomatoes are soil-born. Every time it rains and dirt splashes the lower leaves of the plant the disease spreads. You can only remove so many leaves without causing “sun-scalding” (pale, hard patches on fruit). Even the use of mulch cannot completely stop the occurrence of blight.

With copper spray, copper ions are actually absorbed by the fungus or bacteria and link to the chemical combinations in their proteins, which disables them.

So, we don latex gloves and throw on a backpack sprayer and walk up and down the beds leaving a fine, blue mist in our wake. With a broken gasket on the lid of our sprayer and the requisite jostle to re-mix, there is always an unpleasant trickle of this concoction that drips down one’s back. But, don’t worry about us, safety regulations assert “Zero days to Harvest”, which means it’s even o.k. to eat the fruit on the same day of application.

I still wanted to prove to myself that our efforts are not in vain. Although human health issues are not in jeopardy, continued use of copper can have a deleterious effect on the soil over time.

Is it really worth it?

This season I set up a test to find out. Every two weeks we apply the correct amount of copper to nearly 40% of our total tomato crop. The remaining 60% is left untouched. Of that 60%, 20% are determinate varieties of tomatoes bred primarily for resistance to disease, rather than supreme taste. In other words, half of our yummy heirlooms have been treated and half of them have not.
So far, the results show that the blight has overtaken more of the lower leaves on the untreated plants to the point where they are unable to produce fruit on these lower sections. And, the blight continues to climb ever higher. This is no good. But, I will see the experiment out just to make sure.

Last week, I attended the monthly meeting of small scale growers in our area who are “Organic”, “Certified Naturally Grown”, or folks like us who never use chemicals but haven’t felt the need to bother with the paperwork 😉 I informed some farming friends of my experiment. They laughed and told me there was no need to test it out. Copper works. But, I was glad I mentioned it because I learned that “Champion”, the copper brand we use, has recently been removed from the national organic list. (See OMRI, Organic Materials Review Institute for more details.) According to the certification board, as is usually the case, farmers are allowed to use up their remaining stores of a banned product as long as their next purchase conforms to the new standard.

In fact, I remember in 2003 when “Champion” brand copper spray replaced “Kocide” as the organic standard. The certified “Organic” farmer who I was working for eventually used up his bag of Kocide and diligently bought the new stuff — “Champion”. When I asked him the difference between the two brands he shook his head. No idea.

Therefore, I put out the call to all of you!

Anyone want to research more about the “new” brand of organic copper (I haven’t even found the name of it yet!)- and how it compares to “Champion”? Please consider this a sincere invitation! And don’t worry, our bag is going to last the rest of the season, so the due date for these findings is not until ’09! The reward? Our own delicious dehydrated tomatoes mailed out in wintertime to the first one who responds!


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