Found this incredible old sunflower leaf yesterday while putting up some holiday decorations, but I have no idea what could have led it to look like this. Has anyone ever seen something like this before? (I know it could have been caused by a lot of things not botany specific but I wanted to check if anyone recognizes patterns like this.) We’re located along the Front Range in Colorado.
My guess is a virus of some sort has caused those markings, but I'm not an expert with viruses.
You might be right, kinda reminds me of a picture I saw of a watermelon mosaic virus. Similar patterns but don’t know if other types of plants get those
a lot of plants get those
Could be a fungus feeding on the dead leaf.
That sort of circular pattern, with expanding focal points around it, matches how organisms can spread. Sunflowers are native to the Front Range, so i would not be surprised to see interesting organisms that live on them.
Pretty sure that’s a fungus, those concentric rings are typical.
Concentric lesions like this can be commonly found in both fungal and viral infections. I’ve seen this pattern recently in Botrytis spp. infections. I have also seen similar in Colletotrichum (Anthracnose) infections.
I’ve seen symptoms like this on other plants for Impatiens Necrotic Spot Virus. I have yet to see this on Sunflower. Other viruses I’d guess would be Tomato Spotted Wilt Virus or Cucumber Mosaic Virus. This doesn’t resemble other viruses sunflower get to me.
10/10 thought that was a scrunchie lol
Uzumaki.
Some kind of fungus. I have a little birdhouse gourd I grew this summer that got that EXACT pattern on it while it was drying out.