Tomato disease - early blight?
One of my tomato plants (and only one) has a problem. It kind of looks like early blight, but I don't see the round spots that I see in example photos of early blight on the web. The plant is not crowded next to other plants (as you can see in my photo). This started within the last few weeks.
This is an heirloom tomato, Marianna's Peace. The other tomatoes in the garden are other varieties.
Is this early blight, or something else? And how should I treat it?
Larimer County Colorado fruits and vegetables
It could be either late or early blight, but I didn't see any lesions on the stems of the plant from the photos you sent. That doesn't mean they aren't there, but in the case of late blight, you would see brown lesions on the stems. With early blight, you generally see brown concentric rings on the leaf or fruit. From your photos, the fruit appears to be unaffected.
If it is a blight, then the plant should be pulled, as the fungi can overwinter in soils. If you don't want to pull it now, you can wait until the end of the year. You can remove the leaves that are most infected and see if the fruit will develop. You can also prune lower leaves to prevent splashing.
Have you made any cultural changes to how you're growing the tomatoes? I see they are covered with plastic mulch...is the irrigation working properly? Have you checked soil moisture?