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Septoria (?) Trouble Controlling - chlorothalonil
For some strange reason, the database permanently deleted this thread when I made it into a "sticky". I was able to copy and paste it from another open window, but as you'll see, it's far from perfect. 
tam91
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Join Date: Aug 2010
Location: IL
Posts: 13
21 Hours Ago
From researching it, I am guessing a few of my plants have septoria - photos follow (I hope) - does that appear correct?
I have been spraying with chlorothalonil - which is what I believe the frequently recommended Daconil is. However, my brand is concentrated Ortho Max Garden Disease Control. Should that suffice? Is there any difference between the brands? I'm not sure I've seen Daconil in the stores, but I'm not sure about that.
Most of my plants are fine, but I am having trouble controlling the disease on a few. I've picked off the yellow leaves, and I spray weekly (or more after rain). One of the poor things will be bald soon though if this keeps up.
Can I get your wisdom on this one?
Join Date: Apr 2010
Location: Detroit, Michigan
Posts: 173
21 Hours Ago
I am not a disease guru here.......I will tell you one thing though. Daconil is a "preventive" disease fungicide. Daconil will NOT cure any disease that your plants may already have unfortunately  >>>>>>>>>Talon
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# 2 Talon1189
Talon1189
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Location: Detroit, Michigan
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20 Hours Ago
Quote:
Originally Posted by tam91
Thank you - I do understand that. But I thought if you kept the plant well sprayed, and removed diseased foliage, that perhaps the remaining foliage could stay disease free?
Or am I mistaken, and the disease is systemic and will continue to progress?
Remove the diseased foliage ASAP. I would wait for a more experienced tomato grower for a second opinion here shortly. Good luck with your plants >>>>>>>>>>Talon
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carolyn137
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Join Date: Jan 2006
Location: Upstate NY, zone 4b/5a
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20 Hours Ago
Quote:
Originally Posted by tam91
Thank you - I do understand that. But I thought if you kept the plant well sprayed, and removed diseased foliage, that perhaps the remaining foliage could stay disease free?
Or am I mistaken, and the disease is systemic and will continue to progress?
NO, the disease isn't systemic although stem lesions can be seen. Daconil is an excellent preventive and you're correct in saying that if you keep up a regular spray schedule, making sure to reapply after rain, as well as taking off any diseased leaves, that the plants should do well.
Initial infections with Septoria are via air and embedded in rain droplets so if it's in your are there can still be infection via those routes.
But if your plants have had Spetoria before then spores are shed to the soil and the next year you can get splashback infection that will infect the lower leaves and then proceed upwards on the plants.
Daconil works b'c the molecules bind to the attachment sites on the leaf surface where the spores would normally attach and blocks them from attaching. But it isn't permanent which is why you have to respray.
Daconil is also excellent for Early Blight ( A. solani) and the best we have for Late Blight ( P. infestans)
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Carolyn
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RayR
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Join Date: Jun 2010
Location: Cheektowaga, NY
Posts: 20
 20 Hours Ago
Quote:
Originally Posted by tam91
Thank you - I do understand that. But I thought if you kept the plant well sprayed, and removed diseased foliage, that perhaps the remaining foliage could stay disease free?
Or am I mistaken, and the disease is systemic and will continue to progress?
Oh Septoria, I know it well. That's what it looks like and this is the time in summer that it is most active I think. Chlorothalinol won't cure it anymore than any other fungicide. I've been seeing more outbrealks on some of my tomato plants now. There is no magic bullet that will rid you of Septoria Leaf Spot completely, you are outnumbered by the spores. After you think you've got it under control on one plant, it suddenly shows up overnight on another.
Septoria is not sudden fatal disease like Late Blight, but it's ugly, can defoliate your tomato plants if not controlled and of course reduce your yield.
The best control is like you are doing already, remove diseased leaves or branches and dispose of them in a trash bag away from the garden, and spray a preventative fungicide, don't forget to spray the bottom of the leaves also. (critical but easier said than done sometimes). Also weed control is a must since Septoria can be present on some weeds and spread to your tomato plants from there.
Choose your weapon, I've used a Chlorothalinol based product before, this year I'm using a copper soap fungicide (Soap Shield) with good results at controlling its spread. Maybe some other folks here have other effective controls they can share.
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carolyn137
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18 Hours Ago
Quote:
Originally Posted by tam91
I have a concentrate, so I guess I could mix it whatever strength I liked. So far, I have been following the package directions.
The label says 29.6% chlorothalinil.
The instructions say to mix it 2 1/2 teaspoons per gallon of water.
That sound ok?
No tam, please don't mix whatever stregth you want to.
The amount to use has been titered, sprayed, and then the plants challenged with the various fungal foliage pathogens to see how many molecules are needed to cover all the spore receptor sites on leaf surfaces.
No sense in using too much and really bad not to use enough.
It's one of the reasons you never want to mix anything else with Daconil ( easier to spell than its chemical name of chlorothalonil) b'c interactions can occur such that there aren't enough molecules to cover the sites.
And as Mark said there are different strengths that are sold but the higher concentrations are for use on golf courses, forest control, etc.,
What you want is the concentrate that says 29.6 % chlorothalonil and that's sold by many companies including Ortho, Bonide, etc.
I remember one time that someone was complaining that Daconil was not working and after asking some questions it turned out he was using the 12.5% concentrate which is completely non effective.
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korney19
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Join Date: Aug 2006
Location: The Niagara Frontier and the Wyoming Valley
Posts: 478
18 Hours Ago
You may want to try 1T/gal, I'm pretty sure that may be the most common label.
Or try Manzate or Mancozeb or Dithane 45 (all same based on manganese++ & zinc++, but the Manzate is powder & "industrial strength" version.) Dithane 45 is always available on ebay under the Hi-Yield or Southern Ag brands in pints, Mancozeb is available under Bonide brand, at horseloverz.com & other places, including ebay.
P.S. I always have trouble figuring which is Septoria & Bacterial Spot & Speck, could you have diagnosed it wrong? I don't think chlorothalonil works on the Bacterials, (Mancozeb does), maybe that's why it's not working???
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tam91
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Join Date: Aug 2010
Location: IL
Posts: 13
17 Hours Ago
Oh nonono Carolyn, I stated that badly. I didn't mean I *would* randomly mix something up. I just meant that if you all thought the concentration was not correct, and advised that it be mixed differently, it was possible.
You're absolutely correct of course, people shouldn't mix things not according to label, I didn't mean to say that at all.
Korney: Oh, I sure could have diagnosed it wrong - that's just my best guess, and I'm no expert. If something thinks it's something else, I certainly welcome any ideas.
Those are certainly good ideas to try - I really wish Red Pear wouldn't die - I like my cherry tomato salad color combination - Black Cherry, Sungold, and Red Pear - it sure would be missing something without the red!
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korney19
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Join Date: Aug 2006
Location: The Niagara Frontier and the Wyoming Valley
Posts: 478
2 Hours Ago
Quote:
Originally Posted by carolyn137
No tam, please don't mix whatever stregth you want to.
The amount to use has been titered, sprayed, and then the plants challenged with the various fungal foliage pathogens to see how many molecules are needed to cover all the spore receptor sites on leaf surfaces.
No sense in using too much and really bad not to use enough.
It's one of the reasons you never want to mix anything else with Daconil ( easier to spell than its chemical name of chlorothalonil) b'c interactions can occur such that there aren't enough molecules to cover the sites.
And as Mark said there are different strengths that are sold but the higher concentrations are for use on golf courses, forest control, etc.,
What you want is the concentrate that says 29.6 % chlorothalonil and that's sold by many companies including Ortho, Bonide, etc.
I remember one time that someone was complaining that Daconil was not working and after asking some questions it turned out he was using the 12.5% concentrate which is completely non effective.
Carolyn, I agree with following labels, but just saying, Bravo ULTREX is for vegetable & fruit crops and it is 82.5%... 
And Equus 720 is 54%... it's listed on Cornell's list of fungicides to treat, among other things, LB:
Foliage: EB, LB, Gray leaf mold, Septoria leaf spot, 1.35-2 pts/A; Fruit AN, Alt. Blk. Mold, Botrytis gray mold, LB fruit rot, Rhizoc. Fruit rot, 2.0-2.88 pts/A. 0 DTH.
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