The purpose of this article is to regulate the registration, commercial use, purchase and custom application of pesticides. Pesticides, properly used for the control of insects, fungi, weeds, and nematodes, and as defoliants, desiccants, and plant regulators and for related purposes, are valuable, important and necessary to the welfare, health, economic well-being and productive and industrial capabilities of the people of this state. However, such materials, if improperly used, may injure health, property and wildlife. It is hereby declared to be a matter of legislative determination that the regulation of the registration, commercial use, purchase and custom application of pesticides is needed in the public interest and that in the exercise of the police power all persons be required to register or obtain permits before engaging in such activities.