Q: I have a problem bug that has been killing my tomato plants and caused them to have black fungus. The same insects have destroyed my garden every year.
A: Whiteflies are having a feast at your expense!
This prolific insect sucks sap from leaves and young fruit. They excrete undigested sap onto nearby surfaces and a black mold grows on it. You have probably noticed ants climbing your tomato stalks in the last few days.
The key to whitefly control is to hit them early. They reproduce so fast that nothing will stop them at this point in early fall.
A couple of organic chemicals work pretty well. Try spinosad (Captain Jack’s Dead Bug Brew) or insecticidal soap (Ortho EcoSense), neem oil or azadiractin (Azatin).
Now that you know what they look like and what damage they can do, start monitoring your plants in late May next year. Spray when detected.
I also think you need to encourage beneficial insects in your tomato garden.
Parasitic wasps, lacewings and lady beetles can keep the whitefly population under control if you get started early. Plant dill, fennel, cilantro, parsley, common yarrow, basil, cosmos, dwarf sunflower and zinnia among your tomato plants.