I think it is just environmental.

Sey

Could be the start of something, or could just be environmental as Sey said.. When in doubt just snip and dispose of it to be safe.. That one leaflet isn't worth the risk..

Not a disease.

Environmental - a rub or an abrasion.

The bit about burn through a drop of water is an old wives tale -- doesn't happen.

Actually Janice it indeed is not a wive's tale. I've personally witnessed it on numerous occasions. Here's the explanation: Sun: As well as water loss, excessive sunshine can lead to scorched areas of leaves, typically on the sunny side of plants and not on the lower leaves, those within plants or on the shaded side. Woodland plants such as Acer palmatumare especially vulnerable to sun damage. Where leaf scorching is seen after watering in bright sunlight the cause may be due to the water droplets focussing sunlight on the leaves causing burnt areas. Smooth leaves are unlikely to be affected as research suggests that the light from droplets on the leaf surface is not focussed on the plant tissue, and water tends to run off smooth surfaces. Hairy leaves may be damaged as the water droplet is suspended over the leaf and the light from these suspended droplets is considered more likely to be focussed on the leaf tissues causing damage. https://www.rhs.org.uk/advice/profile?pid=345

Jean: "The bit about burn through a drop of water is an old wives tale -- doesn't happen."

I didn't just say "water". I said "water/foliar treatments". I've had burns that looked EXACTLY like the photo happen after applying fungicide too late in the morning on a day that ended up being sunny when clouds were forecast. My theory is that any solution with oils or soaps in it, even minute amounts, can increase the potential for damage.

It happened exclusively on my tomato plants with rugose foliage and on my eggplants, which have hairy leaves, so I also think that it has to do with how large the droplets are that the leaf will hold on to, as rugose foliage and hairs hold onto much larger droplets.

Not a myth. Just less likely to happen with plain water on most types of foliage.

I think Fungicide in the sun might have been the culprit. The label didn't specify not to spray during the day, so I thought it might be okay. The fact that I was looking for a sun warning on the label means I knew better and should trust my gut! Thanks all!

In my experience , tomato leaves gt sunburn early on IF not properly hardened off prior to plant out. Once they are acclimated and matured won't get sunburn even when they get wet.

Chemical burn is another issue. Some foliar spray at high concentration can/may cause burn when joined forces with direct sun.

sey

sey: "Chemical burn is another issue. Some foliar spray at high concentration can/may cause burn when joined forces with direct sun."

The spray that burned my plants was not at high concentration.

i planted tomatoes, then gave them a shot of *alaska fish fertilizer* {been doing this for years and years and they love it ....}, however i must have *shot* too far and some of the fertilizer got on the leaves, just spots here and there that looked like yours .... i pinched the leaves off ... no more problems ....