Need help to ID mysterious foliar disease (pics attached)

[Eric02476]

I'm familiar with most tomato diseases, but am really stumped by this problem that's spreading on some of my young tomatos. I really want to know what I'm dealing with so I can take appropriate action.

The only symptom is uniform browning and necrosis between the veins of the leaves. It starts off as several small patches but they grow and eventually the leaf dies. The brown/dead tissue always stays neatly within the veins.

It spreads from older leaves to younger leaves fairly quickly, within 2 or 3 days. The damage tends to be all over the leaf, and its systematic pattern makes me doubt a pest is responsible, at least nothing that's feeding.

Of the 3 pics attached, the single leaf photo is fairly high resolution and allows for close inspection. The other two show branches at intermediate and advanced symptom stages.

I'm in the Northeast (Boston area).

I'd really appreciate any help - this doesn't look like any fungal or bacterial disease I know of, and I don't think it's a nutritional problem.

Eric

[GreenSand117]

Have you checked under the leaves for signs of a pest like spider mites?

[Eric02476]

Yes, I neglected to mention that I've looked under the affected leaves and not found any mites or other pests. - Eric

[RayR]

Eric, are these in their permanent spot in-ground or containers? Or are they not transplanted yet? I get similar looking issues with the extra plants in 4" pots that are overdue for transplanting.

[Eric02476]

Ray, thanks very much for the reply. These are in their permanent spots, in Earthbox containers. They didn't show any sign of the issue until a few days after getting set in the Earthboxes. I always water them in with dilute fish/seaweed liquid fertilizer to ease the transition. Hmmm, could I have used too high a concentration of the fish/seaweed and damaged them? Although I titled the thread with the word "disease," this doesn't quite "feel" like the various bacterial, fungal or viral diseases I've dealt with over the years. Nor does it seem like pest damage.

BTW, I got other seedlings from the same source, a good local farm/nursery, and those are in the ground a few feet away, in raised beds. No such problems.

[GreenSand117]

Eric, you could be right, you may have used a too high concentration of the fish emulsion but I am used to seeing damage from over fertilizing along the edges of the leaves. David.

[Paradajz]

i've seen something very much like this once, but it was during a lab test with plants being exposed to ozone so i don't think it might help you

the speed of the problem development you describe also suggests that it's hardly a disease. most likely it's a combination of nutrients disbalance and exposure to some kind of additional stress.
magnesium seems like a problem here ( starting on older leafs suggests it ), but it could hardly do such kind of damage in so short period of time on it's own, it would need some help such as extreme temp changes with prolonged sun exposure, chemicals exposure/overuse, etc.
anyway, was there chlorosis at first, or it has started as necrosis? also, when the first symptoms appear, is the appearance of the spots equal on both front and back side of leafs or there are some differences?

br,
ivan

[Eric02476]

I really appreciate everyone's replies on this.

@ Ivan, I think it does start with chlorosis first progressing to necrosis in the chlorotic tissue, although it's hard to say for sure because the spots are always brown. But I think it's chlorosis first because the spots initially don't have the papery brown texture indicating dead tissue. I see why you're asking, as it seems from some web searching that interveinal chlorosis progressing to necrosis is indeed a feature of magnesium deficiency.

As to your second question, the spots are equal or nearly equal on the front and back sides of the leaf, although of course they look a little different due to the structural differences on each side of the leaf. So I might be wrong on that.

Interesting that you mention stress/extremes...I do wonder if temperature is involved somehow, perhaps aggravating a nutrient problem, as you suggest is possible. These plants were very healthy seedlings until a couple days after I put them into the Earthbox sub-irrigated containers and I applied fish/seaweed emulsion -- possibly in excessive concentration -- to the root zone. And now that I think about it, doing the liquid fertilizer in an efficient, water-conserving container system is very different than with plants in the ground.

And, we did get an unusual heat wave over the past 3 days, soon after I transplanted the sick plants, with high temperatures at least 15 degrees Farenheit higher than normal. Earthboxes do heat up - they are dark plastic -- and it's very likely that these plants got hotter than their siblings that I put in the ground in deep raised beds a few feet away. I also did not apply the fish/seaweed emulsion to the sibling plants in the ground, but even if I had, it would have dispersed in some heavy rain we got at the start of the heat wave (but not in the sick plants in the Earthbox)

And I will note, now that you mention temperature...this problem has suddenly become much worse right during our heat wave.

The hot weather is going to stop after tomorrow and we are in for a cool week. I will pay attention to the problem plants and post an update as to whether it gets any better with the passage of time and lower temperatures.

[GreenSand117]

Eric, I hope your plants survive this...it seems to be a mysterious foliar ailment for sure. Please keep us updated and again I hope the problem corrects itself/or a cure is found
David.

[RayR]

I think heat stress is the culprit here. We've had some unusually hot weather here some days in in May too. The soil temperature in any containered plant can rise quite high.

Scroll down on this blog page to see the heat stressed tomato leaf. Look familiar?

The symptoms of drought stress is different. I had some of this last summer on some in-ground plants. I think it is more easily mistaken for Early Blight than Late Blight though.

[Eric02476]

Ray, heat stress sounds feasible and it would indeed explain why the containered plants have the symptoms and their siblings in the ground nearby do not. The picture on the blog page does look very much like what I'm seeing.

(Interesting to see the pic of drought stress - yes, if I was just looking at the photo I'd also be tempted to think Early Blight)

So it's a working theory and I'm inclined not to do anything drastic. These are my beloved Rutgers tomatoes, so I was rather hoping not to lose them. I think I'll move the plants out of the full sun and see if that plus the cooler weather this coming week makes a difference.

It's so helpful to talk through this on the forum, doing so helped me think more systematically about the conditions surrounding the symptoms.

[macbettz]

I have the same condition on many of my plants I started from seed. I think its sunburn. As it developed over the course of a couple of weeks during the hardening off process. The new growth is lush and green now that they are in the ground, but the earlier, lower leaves have those brown spots.

[Paradajz]

sorry, Eric, lost this thread somehow, have read your post just now. but still very interested to hear about the further development of those plants

[Eric02476]

Hi Ivan, thanks for your continued interest in my little tomato leaf mystery

I moved the plants to part shade for a few days, and then our weather cooled down to normal. The symptoms have stabilized and don't seem to be affecting newer leaves yet. I'll keep an eye on things and report back, but it does seem clear that this is some kind of physiological issue, not disease.

Eric