Bell Pepper leaf discoloration

[Maxy24]

I planted 8 bell pepper plants in the garden two days ago. The plants were grown from seed and were hardened off a little too quickly, but seemed alright before planting out. It seems like over night two of them got these patches on their leaves. I'm hoping it's sunburn or something like that since these past two days have been around 90 degrees, warmed temps than they have experienced so far. But I wanted to check with you all and make sure it isn't something worse.

[bri80]

Are you watering them in the sun? Or did a quick shower come through in the afternoon followed by sunshine? It's caused by water droplets on the leaves during full sun.

[PaulF]

Looks like sun scald. Water the soil not the plant. Hard to stop the rain, though. The plants should recover.

[Lindsaylew82]

I do agree it's sunscald. I don't agree that droplets of water can cause it. Otherwise morning dew would scald every plant! I'm calling old wives tale on that theory! Watering from the top CAN cause issues with fungus, though.
You can prevent that little sunburn with proper hardening off. They will out grow it, now. I don't think there's any further need for protection.

[bri80]

I do agree it's sunscald. I don't agree that droplets of water can cause it. Otherwise morning dew would scald every plant! I'm calling old wives tale on that theory! Watering from the top CAN cause issues with fungus, though.
You can prevent that little sunburn with proper hardening off. They will out grow it, now. I don't think there's any further need for protection.

Morning dew doesn't cause it because the sun is not intense in the morning, and the water evaporates before the sun gets intense. Water droplets absolutely act as magnifiers and scald leaves during the intense light of midday. I've done this enough times and seen it happen.

I love calling out Old Wives Tales In gardening but this is not one of them.

That damage is 100% water droplet caused sun scald.

[Lindsaylew82]

False! The only way that water droplets can cause burn is if they're not actually touching the surface of the leaves. Drops that are intact with the surface can't burn because the water has a cooling effect. Light can't focus on the leaf because there's no distance to focus the intensity.
Those wet leaves can't cause burn like that.

Look at the results section of this experiment:

https://onlinelibrary.wiley.com/doi/10.1 ... 150.x/full

Now, if a plant is hairy, and water droplets may float on those hairs, then burn may occur because of the focusing distance and the inability for the water to have contact cooling effect.

[MOFishin]

I have quite a few pepper plants like that right now, one or two of which are looking quite a bit worse than that. I definitely watered the soil and not the plants. I may not have hardened them off well enough though. The first rain after I put them in the garden had an immediate negative effect on their appearance.

[Maxy24]

Thank you all, glad to know it's not some horrible disease or pest. I've never been able to avoid getting my leaves wet, I just water with a hose and spray attachment, I will try to be more deliberate about where I point it.

[bri80]

False! The only way that water droplets can cause burn is if they're not actually touching the surface of the leaves. Drops that are intact with the surface can't burn because the water has a cooling effect. Light can't focus on the leaf because there's no distance to focus the intensity.
Those wet leaves can't cause burn like that.

Look at the results section of this experiment:

https://onlinelibrary.wiley.com/doi/10.1 ... 150.x/full

Now, if a plant is hairy, and water droplets may float on those hairs, then burn may occur because of the focusing distance and the inability for the water to have contact cooling effect.

It's all about how you interpret the study. The language says water droplets on smooth leaves are "unlikely" to cause "much" damage. That certainly includes the ability the cause some damage.

This article, for example, interprets the results as proving that, yes, water droplets can cause damage (as you yourself said, in the right circumstances like if there are tiny hairs on the leaves. Maybe the water cupped in a strange way at those spots on the pepper leaves? Maybe peppers do have microscopic hairs? Either way the study actually does the opposite of debunking.):
https://www.scientificamerican.com/podc ... -10-01-12/

Given that I've done this move and watched leaf burn happen, and it looks exactly like the OP's damage, I'll stick to my opinion.

[bri80]

Thank you all, glad to know it's not some horrible disease or pest. I've never been able to avoid getting my leaves wet, I just water with a hose and spray attachment, I will try to be more deliberate about where I point it.

Or just don't water in the middle of the day. Early morning is best, but I water late evening because it rarely gets humid here. If you live somewhere with high humidity, watering at night can spread fungal disease.