The tomato is firm and red but it is emitting white foam at the stem. I wipe it away and it still foams. What is causing this? Thanks
I am not aware of any tomato disease where the stem is foaming, but there is an insect that would cause this. It is called the spittlebug and is a piercing/sucking insect that will suck the tasty juices out of your plant and eventually leave yellow spots on the leaves. In it’s young nymph form it likes to hide on plant stems encased in a foam that it creates to hide itself from predators. If you wipe some of it off, it may just produce some more as it would quickly dry up or overheat without it. I would just wash it off with a stronger spray of water and you won’t likely have any more problems.