how would you protect crops from pests and diseases?

We can protect crops from pests and diseases by the use of the following substances:

• Fungicide is a chemical substance that destroys or inhibits the growth of fungi to prevent infection of plant by fungi.
• Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.It may be a chemical , biological agent, antimicrobial, disinfectant or device used against any pest including insects, plant pathogens , weeds, molluscs, microbes, etc.
• Insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. It used in agriculture, household, etc.