Thanks, brownrexx. I thought it looked like pics of LB, and it certainly moved faster than the usual leaf diseases I've seen. I didn't see any new action today, but it was so cold out that I kept all the vents closed, so there was no way for it to blow around, if it's still lurking. I guess I'll find out in the next few days.

All I can say is, I hope not. I don't see it in the initial pics. In the years since I first started helping with the tomatoes, I only saw it once. It was either late blight or gray mold. And it went fast, in a wet garden with staked, ground bound plants and packed soil. It was a matter of days, from those tomatoes don't look too good to wow what happened!? The tomatoes themselves blotched right up.

It has been dry here. We got under 1/8" on Wednesday, and none before that for quite a while. Plenty of spots coming from the ground up, starting beginning of July when it got hot, but nothing irregular other than needing to water practically every day. No rain forecast until maybe Sunday, 40% chance of 0.1".

The only time I ever had late blight the tomatoes went brown just as fast as the leaves and I got none!
They were plantedin the ground and had no covering.

Late blight is very common here in the UK. We have something called a Hutton Period which is 2 consecutive days with a temperature above 10 Celcius and 6 hours of a relative humidity of 90%. That is when late blight is most common. Farmers use services which alert them to Hutton Periods so they can pre-emptively spray fungicides.

Many gardeners here grow blight resistant tomatoes/maincrop potatoes outdoors because some years you will harvest absolutely nothing otherwise. Last year I had to throw away about 10 kg of green tomatoes because I didn't pick them off the plants quickly enough after I noticed blight on the leaves. It spreads incredibly fast, usually you see it on leaves first then it moves to the stems and finally the fruit. What you have doesn't look dark or 'wet' enough to be blight to me, finger's crossed I'm right!

That is very helpful to know about the Hutton period.

No sign of effects on the fruit so far, but... I had to cut a bit more today. The stems in the upper canopy couldn't be saved. I also found some of the same on two plants at the other end of the greenhouse. In both cases the plants were near a vent to the south side. The upper and outer leaves had been attacked by mites and also suffering from this mildew which blows in from outside. The same upper parts is where the disease progressed to purpling petioles and then the beginnings of necrotic brown patches in leaf axils. So I am starting to think that this is simply a later stage of the mildew, when it affects the stems beginning with the leaf petioles where the leaves were first affected. It spreads from the leaf and suddenly you have the whole leaf stalk turning purple then brown with the fungus. The main stems come next as spores have fallen onto them.

It finally stopped drizzling this morning, and warmed up into the 60's. I opened up the greenhouse and by closing time it was much dryer in there. Condensation was bad yesterday but it was too cold and wet outside to be able to vent it out.

I believe if this was late blight, I would be seeing as much of it outdoors and on all the plants out there. We had temperatures well above the 10C limit and very high humidity over 90% for days on end. LB could affect the potatoes as well, but there's no sign of it. There is some mildew on the outdoor tomato leaves but they benefit from better air circulation so it is less severe. That's what I'm thinking now. Humidity and high heat is always the trigger for the mildew.

Don’t think it is late blight. You would have significant stem lesions and tomatoes would go spotted and black and plant would die within 2-3 days. I have experienced late blight only twice — only in September — and when it is cool and wet. It is devastating and takes everything out all at once.

Sorry I tried to upload photos but they didn’t load.

Thanks for advice MissTee. This is definitely a 'hot and humid' disease.
I would love to see pics of the real "late blight" if anyone does have them.
[mention]MissTee[/mention] I had the same problem last night, some kind of server error which hopefully is fixed by now... if not, we'll fix it.

I have no photos but I noticed that the LB lesions appear to be "sunken" into the leaves and that the lesions also get on the stems unlike other diseases. The color of the lesions looks like a grayish brown.

I did not see it on the fruits right away.

Yeah, isn't it true, the last thing you think of when you see some pestilence is "Gotta get a picture of that!".
I have some more pics taken though, and will post if they came out decently at all. No UV filter on the camera so the light can be impossible at times.

Late Blight photos - Sept 20, 2017.

I tried blight resistant varieties in 2018 but they were unimpressive. But no blight that year or since (knock wood), so back to growing tasty heirlooms and open-pollinated varieties again.

Thanks for that MissTee. Your pic shows that the white spore surfaces are really noticeable. It also looks much blacker than whatever funk has been bothering my plants. I checked my potato patch yesterday and there isn't a sign of anything on those leaves, as there would be if LB was blowing around the area.
Those are great pics. Horrible, but great!

Well it is or was definitely not LB. One more round of pruning this morning, mostly mites bites. Moved two more plants outdoors, gave them a little water and opened all the vents. Cool overcast day with a high around 65F and the relative humidity outdoors was a steady 93 percent all day. When I checked this evening there was nothing new to prune.

Yeah, that's about what I remember, MissTee's pics.

Now throw those nasty pics away so they don't infect the other tomato pics on the site. Let alone if it spreads across the rest of the internet's tomato pics. And don't compost, trash or burn!

i agree. I felt like I jinxed the site and all of us just by posting those pics. Hopefully we all have a Late Blight-free season.