Is my tomato plant diseased?

This morning my tomatoes plant had this black residue on lots of the leaves. I prunes the affected stems off, but when I got home from work at the end of the day there was more on more of the leaves.

I've been having caterpillars, so last night I sprayed on some insecticide (slide 3) to try manage this. Not sure if this is relevant! I'm in Western Australia.

Any help is appreciated. First time growing tomatoes.