early blight on tomatoes

GraceHintzeJanuary 15, 2012

A new year begins and I'm already worried about early blight. I've used Serenade, moved plants to new locations, started plants from seed in sterile soil, mulched heavily etc. I can't seem to get rid of it once it starts.

Any help?


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Grace, I'm north of you but still on East Coast where I think the early blight is particularly bad. I have tried all that you have tried, to no avail, plus I have used grafted tomato plants from Territorial Seeds. The grafted plants (which are expensive) showed a modestly better resistance to the early blight. The reason new locations do not work is that the blight which is in the soil can be carried by air at least hundreds of feet. This year I am letting most of my beds rest and am planning to buy tomatoes from the local farm stand. I understand researchers at Cornell University are working on a resistant variety; we can always hope. George

    Bookmark   January 15, 2012 at 12:03PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

If you browse through all the other discussions here about EB you'll find that the most common recommendation is the frequent, regular, weekly use of Daconil fungicide from the first day of plant out.

Unfortunately that is the ONLY way to increase the odds that your plants don't become infected - prevention from day one.

Once infected, and yes it is an airborne fungus, then the plants cannot be cured, merely supported in the hopes of at least some production.

Other things that may help somewhat is to greatly increase your plant spacing to improve air circulation in and among them (4'spacing or greater) so grow only 2 plants where you were growing four, stake and prune the plants heavily to increase air circulation, avoid wetting the foliage, rotate crops as much as possible, remove any affected foliage ASAP and dispose of it away from the garden, don't enclose the tomato plants by taller plants (ie: corn) as that blocks airflow, and as your weather permits plant earlier and then plan to replant later.

Early Blight (a.solani) is the most common tomato disease and despite all of the above, without the regular use of fungicide, it is just something we have to live with.


    Bookmark   January 15, 2012 at 2:11PM
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I garden in far west central Pennsylvania and also in far east central Ohio. We have cool damp springs here with lots of rain. Local gardeners like to refer to our area as the "Blight Belt".

For years I depended on Maneb alternated with Daconil as my best defense--however, still suffered lots of plant losses and reduced yield due to infected plants.

Several years ago, at the suggestion of another Garden Webber, I tried a natural product named Actinovate. At the same time I learned of the antifungal properties of potassium bicarbonate which is pretty much benign to humans.
(We cook, gargle, soak our feet, and brush our teeth with a very similar product called sodium bicarbonate which is common baking soda) Now I certainly don't recommend consuming either of these maaterials in any quantity where it can be avoided but they are both much safer than complex
organic based chemicals like Daconil or Maneb.

Now what I do is prepare a root drench with some of the Actinovate and put a cup of it into each planting hole for tomatoes and peppers. Immediately after planting, weather permitting, I spray my whole garden area and newly planted tomatoes and plants with an Actinovate+potassium bicarbonate+spreader/sticker spray.

When the tomatoes are starting to set fruit I spray a second time but add some Miracle Grow or Jack's tomato food to the spray.

Last year I sprayed a total of 4 times through the summer
and into the early fall. I lost one plant to leaf disease
and had to rogue it out at the 2nd spray time but all the rest did fine for me with very little leaf distress.

I still hold my Daconil and Maneb in reserve for a really bad bout of Disease but for the past two years have not had to use it.

By the way, I typically grow 50 to 60 tomatoes, and most of them are heirlooms.

You can find both Actinovate and Potassium Bicarbonate,
supplied with instructions, by Googling. A local greenhouse or nursery might be your best source for a
spreader/sticker, you will find a little goes a long way, and it is pretty much a benign "glue" to keep your spray materials on through a few rains.

    Bookmark   January 19, 2012 at 11:44AM
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Well...I think that too avoid blight, in my assumption, is to start with healthy plants. I think blights are unavoidable personally where I live..rainy and humid/hot. Once you put them in the ground, make sure they have the right nutrient levels in the planting holes. Calcium and Phosphorus are two key players. Tomatoes are heavy feeders.

    Bookmark   February 10, 2012 at 4:16PM
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Genetic resistance is another important tool in preventing early blight. Several of Randy Gardner's lines have significant tolerance to both early blight and late blight. I am working with some of his breeding material and hope to have a stable variety worth releasing for 2013.


    Bookmark   February 10, 2012 at 7:06PM
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I went to a seminar over the weekend where the speaker recommended really thick mulch - at least 4" if not over a foot of mulch. Has anyone tried that? I don't worry too much about early blight on my plants since it doesn't seem to hurt them too much in the short season we have here. I'd try the thick mulch if I thought it would work but it seems unlikely since I would only be covering a fairly small area.

    Bookmark   February 13, 2012 at 2:14PM
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Thanks for being so detailed on actinovate. I have had problems with blight annually even before the major blight in ne a few yrs ago. It's a major downer. Definitely going to go the actinovate route this yr and if I can maintain just 80% green thru season I will be happy gardener.

I have never had blight on peppers though. I was thinking about just spraying my tomato plants or do you think that everything in garden should be sprayed for better protection? Thanks

    Bookmark   February 19, 2012 at 8:32AM
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carolyn137(z4/5 NY)

Fusion, yes, Randy Gardener has a couple of varieties tolerant to, but not resistant to, Alternaria Solani, Early Blight, but as he told me it's mainly for large scale commercial farmers who can spray anti-fungals every 7-8 days rather than 4-5 and for them it's a huge savings.

But I don't see them as being useful for the home hobby grower.

HOwever I have grown Mountain Magic F1 and Plujm Regal F1, two of his newest with EB tolareance, as you know, but couldn't assess any EB tolerance since the past couple of years there's been no wind or raindrop embedded spores in my area. And I really do like Mountain Magic F1 for other reasons as well.

I just wanted to comment that both Early Blight ( A. solani) and Late Blight ( P. infestans) can appear either early OR late in the season, so it's rather crucial to make a proper diagnosis since Late Blight does not have a good prognosis at all, and those of us in Late Blight areas have available to us few preventative sprays, Daconil being the best.


    Bookmark   February 19, 2012 at 3:40PM
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I think you will do well using Actinovate. I use the root drench on both tomatoes and peppers. By the way the directions for mixing are with the packet.

Actinovate seems to be pretty much listed for spray
application to most anything in the garden. I think my melons do particularly well with a couple of cover sprays.
I've never used it on my pole beans as it doesn't seem to be much needed there.

Don't set aside my recommendation for the potassium carbonate as it is just as important a treatment as is the Actinovate. You can get maybe 75% the effect of potassium bicarbonate by using just home style baking soda which is sodium bicarbonate. Will save you a lot of money, also. I think your local ag agent can give you mixing and application suggestions. It's been used on roses and veggies for a zillion years. Somewhere I read that the experts would rather suggest potassium bicarbonate to avoid the buildup concentration of sodium in the soil-I can't get too fired up about that- but I have used both and the potassium seems to work better.

The use of spreader sticker will multiply the usefulness
of your spray materials by multiples!!!! Whether you are applying nutrients or materials to fight leaf crud the sticker just keeps the goodies in place through rain and dew
to see that it can do it's job. As the plants grow, so does the exposed area of the leaves and fruit. So what was applied is "thinned out" by growth. Eventually, it's a good thing to spray again to keep a credible dosage in place where it is needed. But just remember, none of it will stay in place very long without the sticker!

One more comment: I have so far never had to deal with Late Blight. At least I seem not to have ever suffered from it. Three possibilities exist---1)it isn't around in my area or 2) I have been very lucky or 3) Whatever I have been doing for the past 25 years to deal with early blight seems to have handled the late blight as well.

    Bookmark   February 20, 2012 at 3:54PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

I went to a seminar over the weekend where the speaker recommended really thick mulch - at least 4" if not over a foot of mulch. Has anyone tried that? I don't worry too much about early blight on my plants since it doesn't seem to hurt them too much in the short season we have here. I'd try the thick mulch if I thought it would work but it seems unlikely since I would only be covering a fairly small area.

athenainwi - that is a standard recommendation and has been used by many of us for many years. The thick mulch serves multiple purposes.


    Bookmark   February 20, 2012 at 4:27PM
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I was given a "recipe" for blight by someone two years ago. I have not used it, but will use it this year. It is 2 tablespoons baking soda, 1 light tablespoon chlorox, and 1 tablespoon of Murphy's oil soap. This is for one gallon of water.
I also mulch heavily to keep soil borne splatter to a minimum, I pinch off any leaves w/in a foot of the ground, I irrigate by a soaker hose system, and I remove infected leaves ASAP.

    Bookmark   February 20, 2012 at 8:26PM
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hey larryw,

wondering what you use for a spreader sticker. I called one supplier and to my surprise he said that yucca extract was a good spreader but not sticker.

I looked at coco wet but a couple of the reviews I read said that it killed their plants. So what do you use?

    Bookmark   April 20, 2012 at 4:28PM
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