That old question about the best organic fungicides!!

ladonMarch 19, 2013

Hey gang! How's everyone doing? First time back since summer and of course it's that time of the year to start planning out our strategies for summer gardening. Here in Southern California we're getting pretty close to being able to plant out our tomatoes. So I'm throwing out the same question that I do every year, because every year I have the same problem with my plants...and my solutions (which are different every year) yield different degrees of success... My issue is this...every year around mid summer, regardless of what kind of fungus treatment I use, I start getting yellow spots on my leaves, which eventually start to spread. Those leaves eventually turn brown and dead looking until this ultimately spreads through the whole plant. This usually occurs over the course of 2-3 months, and although I almost always end up with a great yield, the plants do suffer. And ultimately it does effect production. I've gone different routes to combat this situation, which I believe is caused by a grey mold, very prevalent in So Cal. I've tried Serenade and other organic methods. Last year, in an attempt to be more aggressive, I actually tried Daconil, which although a bit more effective, made me very uncomfortable and I don't want to use it again. So I'd love to have you all weigh in on what has worked for you as an effective fungicide...particularly if you live in Southern California. Please discuss products AND methods if you could, including frequency of application and techniques. Thank you all in advance for your input. Looking forward to a great season!!
All the best,

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carolyn137(z4/5 NY)

Don, I really think that you need to make a definitive Dx as to which specific diseases your tomatoes have.

Your description of the yellowing leaves with spots could apply to either of the two common bacterial foliage diseases, as well as the two fungal foliage pathogens.

And if bacterial Daconil won't do a thing, it can 't.

Yellowing leaves with no spots can also refer to some of the soilborne diseases you have in SCal,such as Fusarium and even nematodes.

So IMO it's best to make some diagnoses before trying to find something effective against what you're trying to prevent.

I have a more kindly view of Daconil since it's less toxic than Rotenone and the latter is certified organic by most organic certifying agencies.

Personally I don 't care if a product is organic or not, I just want a product that does no harm to humans,pets and the environment, as in low toxicity.

But let us NOT discuss Daconil here since there so many threads already here about it for anyone who wants to do a search.

Hope that helps, even though I've not discussed organic anti-fungal products and there are no effective anti-bacterial organic products that I know of unless you want to consider copper, which has marginal effectiveness, and that has its drawbacks as well.


    Bookmark   March 19, 2013 at 5:45PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

I agree that you need to first know exactly what disease or diseases you are suffering from. Without that knowledge any information about treatment is pretty pointless given all the variables.

But I would point out that ALL fungicides, if what you have is a fungus disease, are preventatives not cures. Once the disease has taken hold it won't matter which product you choose to use or how often you apply it. All you can hope to do at that point is slow it down.

That means they have to be used from the first day of exposure to the outside, used regularly as per the label instructions (usually weekly and after rain), and applied per the methods recommended on the product label.

If what you have is one of the bacterial diseases then, as Carolyn already said, fungicides are relatively pointless. In that case you'd need to look into copper sprays and making multiple changes in your growing/cultivation techniques.


    Bookmark   March 19, 2013 at 6:12PM
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I was going to give you a link to another forum with good info but GW is still living in the past, like about seven years ago and the attacks should be singular (Attack). The whole idea of these forums is the passing of information, not suppressing it do to somebodies ego being hurt. Get over it!

" Spam Alert:

In order to fight spam, we need your cooperation!

Unfortunately, we have been the victims of spam attacks (the posting of ads) promoting this site or business (XXXXXXXXXXX) and they are now blocked completely to prevent a recurrence.

Please do not mention them in our forums or elsewhere at this site.

Any attempt at circumventing this block by using our site to refer others to this business will be interpreted as an attempt to further spam our site and you will be permanently banned from using our services.GardenWeb

We appreciate your cooperation in keeping messages ad-free!

    Bookmark   March 20, 2013 at 3:28AM
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carolyn137(z4/5 NY)

Well said Ami, b/c I was going to attempt to answer the question by linking elsewhere but I've asked several times if linking to other message site threads to help answer questions could be done without someone being banned here, and have never received a definite answer,

How does one distinguish between an "ad" and another message site or to even a Google search that would bring up links to several disease sites.

I did check the Pest and Disease Forum here last night and I can't find any of the links that many of us entered that would help folks make diagnoses for various diseases and pests.

Tamara, could you please help clarify for us? It would be greatly appreciated.


Carolyn, who should have also put this post in the correct thread which was the one at the top asking a huge question about pests and diseases, but it goes here as well in terms of organic fungal products, in a general sense.

This post was edited by carolyn137 on Wed, Mar 20, 13 at 8:24

    Bookmark   March 20, 2013 at 8:19AM
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Not sure what is going on here but I'll only note that there are many new OMRI approved fungicides on the horizon that have shown effectiveness in controling various diseases. You probably should contact an extension agent in your area to find out what is approved for your state.

Also what Dave related about fungicides being only preventative needs clarification. There are various fungicides which act as curatives if you treat the disease at an appropriate stage. Even tough fungal diseases like Late Blight can be held in check. I could mention quite a few trans-laminar acting materials but it might be considered an endorsement for Bayer, Dupont or Marrone Bio Innovations.

    Bookmark   March 20, 2013 at 6:18PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Good point. Below is the current OMRI approved list. Unfortunately many of them are not available to the average home gardener.


Here is a link that might be useful: OMRI Approved Fungicide List

    Bookmark   March 20, 2013 at 6:58PM
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A good combination for foliar applications is Actinovate and EXEL LG (Phosphorous Acid) which is Bio Friendly. They can be mixed together and applied at the same time.
Gauge your applications to the weather conditions. When you have warm, humid, rainy conditions apply at least twice a week. Hot, dry conditions every two weeks should be sufficient.
Good plant health is a must as plants under stress are more susceptible to disease.
One final note, during plant out it is best to inoculate the root ball with beneficial fungi and bacteria prior to putting them into the ground or aggregate if containers are used. I use Actinovate and MycoGrow soluable mixed in water and use as a dip. You can also use powder forms and dust the rootball or planting hole as well. They will increase the plants nutrient uptake as well as protect the plant from soil borne disease.

    Bookmark   March 22, 2013 at 9:31AM
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Thank you all for your input. Yes, I'm aware that diagnosing the problem is the first part of the battle. It's occurred to me that over the years I've been making guesses about what is affecting my plants. I've posted pix and also brought affected leaves to local garden centers to get feedback on what I might be dealing with. But is there any definitive way of finding out for sure? Based on what I've read or been told, I've always assumed it was something fungal... But maybe it's not. I live in Los Angeles. Is there a resource here in this sprawling metropolis for home gardeners to get diagnostics on our plant problems? Then I can really make a better decision about what to combat it with....Of course, my goal is to treat the plants from the beginning to avoid having any disease onset in the first place....but if it does occur again (which it has every year for the past 10) where might I go?
Thanks again,

    Bookmark   March 26, 2013 at 2:34PM
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carolyn137(z4/5 NY)

It all depends on the expertise of the folks at a particular nursery as to how much they know about tomato diseases when you bring something in for diagnosis.Some are good and some don't know much at all.

Below I've linked to the Coop Extension places in LA County, which might be a better place to look into.

Hope that helps,

Carolyn, a tleast I thought you were in LA, if not just Google Coopeartive Extension places in other parts of So Cal, where you did say you lived and gardened

Here is a link that might be useful: Ccop ext, county

    Bookmark   March 26, 2013 at 3:59PM
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Someone told me about this a few years back. I have never tried it, but will this year. May not be "organic" enough for some.

In one gallon of water:
2+ tablespoons of baking soda
1 tablespoon of Murphy's Oil Soap
1 tablespoon of bleach

    Bookmark   March 27, 2013 at 10:04PM
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OMRI is a only has to be like 17% organic to get listed. Look deeper into most OMRI products and you will be supprised at what you find!

    Bookmark   March 27, 2013 at 10:57PM
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