Mon Jun 23, 2008 5:55 pm

My garden is in full swing with 7' tall producing tomato plants.
I have just noticed the bottom leaves on several of my tomato plants starting to die. Leaves are fringed in a burnt brown. Upon asking a local tomato grower and showing him my leaves he said I had the "blight". He told me to spray with "copper" spray to take care of it. He said to soak the leaves affected and he has given me some spray to use. My ?'s....
What exactly is "copper" spray?
Is it safe?
Is there an alternative?

Thanks in advance!!
Mary Lou
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Mon Jun 23, 2008 8:43 pm

Congratulations on your large tomato plants! Sorry to hear about the blight.

When you say you asked a "local tomato grower," is this person a large-scale farmer? a market gardener? a home gardener?

The answer you receive often depends on the kind of growing your expert does. Market gardeners and home gardeners are more likely to use organic approaches; large farmers (vast majority, at least) still aren't using organic methods.

Please visit your local nursery/garden supply store with affected leaf samples in a ziplock-type bag, and read the labels of the various copper products. Be sure to find out whether these products are toxic to fish, can or cannot be discharged to bodies of water (this also means cleaning the equipment in your sink), whether they can be used on edibles, how long before harvesting it's safe to use them, etc.

I've never used copper products, so I personally don't know the answers to these questions.

Do some calling around based on--yep--the Yellow Pages. Sometimes you can get a good idea of a business's approach to gardening via their Yellow Pages ad combined with their website without even getting into your car.

Good luck with the tomatoes.

Cynthia H.
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Fri Jul 04, 2008 1:55 am

copper is a natural fungicide though it is a heavy metal. Also you may try "neem oil" available as "three in one" product names. Increase air circulation, avoid cultivating to close to the plant trunk and make sure watering is even
greg draiss
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Sun Jul 06, 2008 6:08 pm

Your question about copper made me think of treated lumber and the new copper replacement for the old arsenic compounds. Here is what one article says about copper in the new treatment. Am not sure whether this info has any bearing on your question or not.

After January 2004 the CCA preservative will be replaced with ones that contain no arsenic or chromium. There are two major replacement formulations. One is ACQ, sold under the trademark Preserve Wood. This formulation is a combination of copper and didecyl dimethyl ammonium chloride (quat). The other is copper azole, sold under the trademark Natural Select. This formulation contains copper and tebuconazole. Borates can be added to the copper azole formulation, and may be approved for other uses, depending on the application.

These new preservative formulations do not contain EPA listed compounds, nor do they contain known or suspected carcinogens. The ACQ formulation was given the green chemistry award in 2002. Unfortunately, the toxicity of copper to some beneficial marine organisms presents problems for the use of these preservatives in marine applications."
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Wed Jul 29, 2009 4:20 am

Any more thoughts on this issue?
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Wed Jul 29, 2009 12:48 pm

Useful info about copper sprays: ... copper.php

I'm not a big fan of copper, although I will use it as a last resort if nothing else will work. In my experience it doesn't work all that well. Some copper products aren't approved by OMRI either.

Copper gets into the soil when it washes off a week or two after you apply it. It gets into the compost heap if the plant is composted. It does not break down or leach out, and it's toxic to earthworms and beneficial microorganisms that inhabit the soil in your garden. If the spray drift or discarded leftover spray reaches a stream or pond, copper is toxic to the aquatic life there (don't dump leftover spray down the drain!).

If you use a lot of it every year, it's a good idea to test your soil occasionally to monitor copper accumulation.

What kind of blight did the tomato grower say your plants had? Leaves fringed in brown sounds more like fertilizer burn or too much hot dry weather to me. Early blight or late blight would cause big dark spots on the leaves, not brown fringes.
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bottom leaves turning brown

Wed Jul 29, 2009 1:19 pm

Are you sure you even have a blight? It is perfectly normal for the oldest, bottom leaves on the tomato plant to turn yellow (usually not fringed in brown) and die. As long as the plant is still producing healthy green leaves on the top, that's not a problem.

Pictures always help!
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Wed Jul 29, 2009 4:07 pm

This thread started a year ago and was dormant for a long time. Here are some current discussions on the late blight reported in the eastern states:

1) What is destroying my tomatoes? Verticillium Wilt? images

at ... hp?p=85514

2) "Late blight" disease reported in several eastern states

at ... hp?t=16634

3) Is a copper fungicide organic?

at ... hp?t=15490

Good to get a reference to all three of these threads in one place, since they're not all in the same forum....

Cynthia H.
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Tomato Blight

Sat Oct 03, 2009 10:20 pm

I'm curious, is anyone doing anything now in the fall to prepare soil to be blight resistant next year?
Also what did you do with your blighted stalks? I can't burn mine as they are too moist.
What about the mulch hay around the plants? It must be infected but I imagine the blight is all over and can't really be eliminated.
I want to help the soil and subsequently the plants as much as possible next year. Someone said mineralization but what does that actually mean?
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Sat Oct 03, 2009 10:44 pm

I'm leaning very heavily toward the succession answer to the blight. This year my plants were the most vigorous even, over seven feet tall in the second week of July, by the first week of August those plants were all but dead.

I cut the apparently healthy top out of one diseased 'sweet cluster' plant and used them for cuttings to start new plants. At the same time I started some new seedlings. All but one seedling died from dampening off as the plants were left in an automatic sprinkler zone too much of the time. Here it is September and all of the 'sweet cluster' plants are thriving and full of tomatoes. The one seedling, a 'super Sioux' is also thriving and loaded with tomatoes.

So next year my strategy will be two fold. First, starting in mid July or after a rainy period, I will spray my plants with dilute milk spray and dilute peroxide spray. At the same time I will start fresh batches of seedlings from late may until mid June. I will also make some cuttings from favored plants.

What I've found is that young viorously growing plants are not affected by the blight so much. So if you have some replacement plants growing at various stages, any lost plants can easily be replaced. Also, I've noticed both this year and previous years that container plants grown in sterile soil do not suffer from blight nearly as badly as those in the ground where the disease has accumulated over the years. One last strategy that I'm considering it to grow some tomato plants under a shelter, so that the rain never touches the foilage. The plants will always be bottom watered. Will see what happens in that experiment. It seems to me that I never have a serious problem with blight until we have a two or three day rainy period in July, then the blight marches right up the plant, killing most within a couple of weeks.
Eclectic gardening style, drawing from 45 years of interest and experience. Mostly plant in raised beds and containers primarily using intensive gardening techniques.
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