Q.what does fungus or mold look like and How do you treat it?
My tomatoes are black on the bottom and pepper plants are black in the elbows of the branches. Do I have 2 dispose of the whole plant or is there a treatment?

Certified GKH Gardening Expert
It sounds like your tomatoes may have some blossom end rot, which is treatable. Here is more information: https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-blossom-rot.htm
As for the peppers, Bell peppers often have a purple-black coloration at points where stems meet, but if the black color is a solid black and the area is shriveled, this would indicate a possible issue, such as stem scald, which normally happens on the main stem. What happens is a heat source can focus heat on a part of the stem and it wilts.