Help - can someone ID this foliage disorder? (pics)

[Eric02476]

This progressive brownish discoloration started appearing on lower leaves about 2 weeks after setting out my seedlings in EarthBoxes. It is spreading to upper leaves and also appears to be spreading plant to plant -- or at least it's affecting the other plant in the same EB and the plants in the adjacent EB (1 foot away).

The discoloration gets darker as time passes, and the leaves on the oldest affected leaves are now curling. The discoloration is on both sides of the leaves. Suspecting a fungal disease, I did start spraying with Daconil shortly after the first symptoms appeared. It hasn't seemed to stop the spread, although I was using 2-3 year old Daconil (I just bought new stuff today).

The affected plants are now about 10" and are still producing new growth, but I don't know if they can outrun this. I am very concerned.

I have consulted many online tomato problem solver photo sites and cannot recognize this particular pattern. I don't know if this is a disease or a physiologic problem. We've had some temperature fluctuations and some cool, wet weather recently.

Does anyone recognize this? (See photos attached). The photos show an earlier stage and a later stage - the later stage shows the leaf curl. I'm in Zone 6A, eastern Mass.

[gflynn]

Eric,

My wild guess is sunburn. I think that it may have held back due to cloudy weather and rain but after a day of pure sun it struck. If I am right this is a common hardening off problem. I see stuff like this every year. Part of the problem is that the plants are growing very fast this time of year and they have lots of new foliage so even if you had a week of rain and then a day of sun after harding off you may still see this problem.

Greg

[Vince]

Not sure what it is? But I would like to politely disagree to the sunburn diagnosis. Have seen sunburn, but never like this. Looks like it MAY be a mold or bacterial speck or something(Just my unmedically unscientific opinion).

[dice]

The leaf curling could be environmental (cold), while the
necrosis in the leaf tissues could be bacterial, fungal,
or the result of some chemical toxin (unrelated to
the curling).

It looks kind of like the later stages of a variety of
mineral deficiencies, too (the leaf curl in particular
makes me think of that), but if so, there should be an
earlier stage, before the necrosis, where the leaves
show some purple or yellow spots that later turn
to brown spots. I don't see that in the pictures.

[Suze]

Thread moved to pest and disease subforum.

First off, let me start by telling you what it isn't. It's not sunburn, it's not Early Blight, it's not TSWV (not that it's a problem in your area anyway). I also don't think it looks like Septoria spot.

What it looks like to me is alternaria canker (bacterial). I could be wrong, but that is my guess.

http://aggie-horticulture.tamu.edu/t...leaves/8c.html

[Eric02476]

Thank you all for the kind replies. Of all the online photos I've seen, alternaria canker does look the closest to what I've been, although it's not an exact match. In some ways it does resemble nutritive deficiency photos I've seen, but not entirely (as someone noted above). It may remain a mystery but I will post an update if things improve or get drastically worse.

Regarding what to do: It sounds like I should continue my Daconil regimen in case it's fungal (I use it anyway since I usually get Early Blight eventually), and hope that the warmer, steadier temperatures will even things out and stimulate new growth. If the necrosis is bacterial, there isn't anything I can do except isolate the affected plants from other ones, correct?

If anyone does have a positive ID on this based on my photos, do post a reply - I'll monitor the thread.

Eric

[gflynn]

Eric and all,

Although sunburn is generally white it often isn't. It seems that this problem is covering so much of the leaf that either the plant is on it death bed or something covered the leaves.

I would figure sun would do that but Eric mentioned that he used Daconil.

Eric, did you use your sprayer for anything else before using daconil? Some other products can burn leaves even if only a remnent remains in the sprayer.

Greg

[Eric02476]

Greg's last post caused me to remember something -- I did apply the Daconil once in full sun, which I know is a no-no (slapping own wrist). The worst-affected plant still seems relatively healthy and growing despite its problems, so maybe I scorched the leaves by doing that.

Also, I did use the sprayer earlier in the season for an application of horticultural oil (diluted to 3% I think) and an application of BT on rosebushes. No herbicides, though.

Eric

[dice]

At the very least I would cut off all of the afflicted leaves
and dispose of them in the trash (not the compost pile). If
it is bacteria, you don't want the sources of infection to remain
in proximity to your other plants.

[Sherry_AK]

Here's a typical example of sunburn. This little guy was at the sunny end of the cart during hardening off! New foliage is fine though.

[Eric02476]

Thanks again, all. I will cut off the afflicted leaves, keep up with the Daconil (which I do anyway), and see what happens. I'll post an update if anything changes for the better or worse.

[Eric02476]

The plants are quite fine now and the foliage problem hasn't spread. I think I may just have damaged the leaves by spraying the Daconil in full sun two times (I said once below but later remembered otherwise). The apparent "spreading" of the damage was probably due to the multiple applications of Daconil in the sun. Lesson learned -- follow the label instructions!

Now, I can't be 100% sure this was the problem; I did after all remove the affected leaves and started a Daconil regimen so I suppose it could have been something fungal that was arrested by these steps, but this thoughtful remark from Greg suggests to me that the plant probably wasn't that sick.

Originally Posted by gflynn

It seems that this problem is covering so much of the leaf that either the plant is on it death bed or something covered the leaves.

Thanks again for all the replies.

Eric

[gflynn]

Eric,

I was thinking the same thing myself. I was thinking that if your leaf damage was some sort of burn that you would see an immediate recovery instead of a continued problem.

I am not sure if your theory about applying Daconil in full sun is the issue. I would suspect more either sunburn or a residue in the spray tank. That said I am no expert but I do remember Dr. Carolyn becoming very annoyed when I had suggested Daconil burning leaves in the past :-)

Greg

[dice]

That said I am no expert but I do remember Dr. Carolyn becoming very annoyed when I had suggested Daconil burning leaves in the past :-)

Well, it would not be the chemical itself burning it in Eric's
case (which is the assertion that Carolyn would have objected
to), it would simply be the moisture with the sun shining through
it. If that was indeed the cause, the same damage would have
occurred if he had simply sprayed water on them at that exact
time on that exact day instead of water with Daconil dissolved
in it.

As far as Daconil goes, though, the recent discussion about
Salmonella in tomatoes cited some research that found bacteria
like Salmonella seem to thrive in Daconil solution. I wonder if
that is true of bacteria that cause bacterial diseases in
tomatoes as well. (If Eric's Daconil itself is polluted with some
kind of leaf-eating bacteria, I guess he will know about that
soon enough.)

[gflynn]

Dice,

Good point. I guess his assertion is that water would magnify the affects of the sun.

Has that issue ever been discussed at any length?

Greg