Proper nutrition is the very foundation of organic growing and pest control.
Just as a human body that isn't properly fed is wide open to attack from one illness or another, so it is with plants. Chemical fertilizers are not complete foods. They lack almost all of the important trace minerals. There are over 70 trace minerals that plants and humans need, and chemical fertilizers provide only a few of them. If plants do not get the trace minerals they need, as well as a variety of enzymes and bacteria, they will become stressed and will be attacked by disease, or pests.