Early Blight

sher_mesaazApril 20, 2011

We're seeing a lot of early blight on tomatoes & peas in our mesa neighborhood this spring. My neighbor two doors down and I both were fretting over these mysterious brown spots on the lower leaves of our veggie crops and couldn't positively identify it against pictures on the internet. She brought a handful of leaves from various plants to A&P on Baseline and they said people have been coming in droves with the same problem. They believe the hot-cold-hot and moisture trends made conditions perfect for it this spring. They said to use sanitized pruners and take off as much damaged material as possible, bleaching between cuts. Then, to spray what's left of the plant with a fungicide and they sold her something called Natural Guard - Copper Soap Liquid Fungicide.

Also, give the plants air circulation. Try to prune lower branches so leaves don't touch the ground.

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Daconil is a better product for use on crops that require multiple applications of fungicides. Copper from copper based fungicides can build up in the soil to toxic levels. Copper is better used for dormant fruit trees and for vegetables that can get buy with one application. Ask anyone in the Tomato Forum. I have never hear anyone there recommended a copper based fungicide for tomatoes.

    Bookmark   April 20, 2011 at 1:05AM
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Maybe that's what is happening with my plants? Look at my photos:

    Bookmark   April 20, 2011 at 10:57AM
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az_pamperedchef it looks like you are going to be in a battle to save those plants. The bacteria that causes blight hides in the soil and is on the affected plants. I spray my plants whether they need it or not every 2-3 weeks and they are all healthy and beautiful. In the Tomato Forum when a plant shows symptoms of blight the typical response is to pull it out and get it out of the garden. Then expose the soil to sunshine to kill off the blight and plant again in another location. They do that because they have 25-250 plants and they don't want to take the chance of it spreading.

Your case is different. You don't have lots and lots of plants.

In your case I would.....

Cut off all the lower branches.

Cut off all the affected leaves.

Spray with Daconil really well two weeks in a row and then every 2-3 weeks there after.

Add a top dressing of compost to give the plants a little more energy so they can push some new growth.

Control #11 in the link provided below From the University of Maine's Agricultural department says.... "11.The preventative fungicide chlorothalonil (Bravo) used on a seven to ten day schedule gives effective control."

The fungicide chlorothalonil (Bravo) is the active ingredient in Daconil Fungicide.

Here is a link that might be useful: Early Blight of Tomato

    Bookmark   April 20, 2011 at 12:32PM
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Thisisme ~ do you think it's early blight? I don't have any concentric rings on the leaves as described. If it isn't blight do you think it would hurt to use the Daconil?

    Bookmark   April 20, 2011 at 2:24PM
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az_pamperedchef it may or may not be early blight. However there are lots of fungus's that attack and kill tomato plants. Daconil kills them and should be used on a regular schedule whether you see a problem or not.

In this case they need to be sprayed and soon. In addition all affected leaves should be removed along with any and all low branches.

    Bookmark   April 20, 2011 at 4:27PM
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Thanks for the info, thisisme. I can't get the link to work, but think you've given enough info to help. Is Daconil considered organic?

    Bookmark   April 20, 2011 at 11:31PM
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mister_gin(z9 AZ)

Oh wow az_pamperedchef! I'd post those pics over on the tomato forum and see what those folks had to say. I've been noticing some more browning/spotting on the leaves on my Sweet 100 plants (no pic). Seems to be going up more in the middle of the plant. Looks sort of like rust to me, but I'm not seeing anything like you've shown.

My Big Beef plants are exhibiting something even different. The the pic below makes it look like something is chewing thru the leaves, but I've never seen this before. Both are a mystery to me. I've never had to use any type of fungicide before but maybe I should think about it. These plants were bought this year, so maybe it's something I brought into the garden.

Here is a link that might be useful: Latest garden pics...

    Bookmark   April 21, 2011 at 1:38AM
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sher_mesaaz I clicked on the link and it works. Daconil is not considered to be Organic. I don't know of anything organic that works once a plant is infected. No organic products are listed as recommend on any site I have found. Before any fungus is on the plants some people in the tomato forum have used powdered milk. Not something I want to use but you can give it a try.

Here is my favorite link for tomato disease identification.

Here is a link that might be useful: Cornell University Vegetable MD Online Tomato Disease Identification

    Bookmark   April 21, 2011 at 1:58AM
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Foliar funguses are not that common in our hot dry climate. Definitely possible...septoria, alternaria etc but generally they are limited to greenhouse production and the monsoon months because of the high humidity and lack of airflow. Early blight is caused by a fungal pathogen NOT a bacteria. If your peas are showing signs, it could be bacterial blight, not early blight. Most likely what you're seeing is as a result of the crazy weather fluctuations we've been having. Peas especially will be subject to the heat so what you're seeing could just be them drying out? After the week of 100 degree heat and then the drop to 36 degrees with rain (at my house at least), my tomatoes showed signs of environmental stress....Some yellowing, some brownish spots that looked almost like a magnifying glass had been held over the leaf, and drying out and crisping of some leaves. They are totally fine now. Before you rush to chemical measures like Daconil, I would be absolutely sure you have a fungus problem.

PamperedChef, I saw your posts in the tomato forum and I agree with the other replies...it definitely looks like the later stages of weed killer damage. Coupled with the weather fluctuations, you've got some pretty sick plants but it doesn't look like a disease. Bad news is, they're very susceptible to everything now. I would remove the dead leaves and give them a nitrogen boost.

MisterGin, that looks very similar to what happened with my tomatoes. I wouldn't worry about it unless you start to see your plants deteriorate. Your garden's looking great!

    Bookmark   April 21, 2011 at 6:20AM
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I know of at least one member who will not grow tomatoes in Arizona do to Blight and both blight and wilt are covered in the AZ Master Gardener Manual. To each his own though. I am not here to argue. As I said before a little nitrogen and take off all affected leaves. Also take off the lower branches which is just plain good tomato culture.

I can't speak for anyone else but I spray and my plants look good.

    Bookmark   April 21, 2011 at 12:31PM
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mister_gin(z9 AZ)


I really wish I knew what was causing that. For now it appears to be confined to the lower portion of one Big Beef plant. For now I'll just keep an eye on it.


I see now that you did post over in the toms forums. I knew weed killer affected toms but not to that degree. If that is indeed weed killer damage, and it looks severe to me, then they might not pull thru. If you get them going again now the coming summer heat may do them in. The stem color in your second pic doesn't look good to me. Typically when I see that I'm done with the plants. I'm one that doesn't keep them going thru summer though so I don't know how well they come back from looking like that.

Good luck!

    Bookmark   April 21, 2011 at 2:33PM
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