My tomatoes got blight this year. The leaves get brown spots and turn yellow. It starts at the bottom of the plant. Pick off infected leaves and burn them or dispose of them where they will not infect anything else. Be sure to clean hands and tools with alcohol so it doesn't spread. Then I am spraying every few days with Neem oil. It is organic and not harmful to humans or animals.
There is an organic insect spray you can make with garlic and cayenne pepper, but I don't have the recipe. My DD makes it. Just google organic insect spray. You should be able to find it easily.