Hi - I don't know my exact type of plant, as the sign is gone. But all of the yellow cherry tomatoes have black spots at the stem end. There is no sign of rot - the spots are only around the stem, and are relatively flat and sturdy. I cut through one spot so you could see the inside. Can you please tell me what's wrong with them and whether/how I can fix it? This is one of 3 tomato plants, but my only golden one.