Some plants are relatively pest free.
I never have any pests on beans,peas.okra,sweet potatoes,turnips,onions,peppers,melons or garlic.
I seeded out winter wheat and nothing bothered it.
Some plants like tomatoes,cukes,squash and cabbage have more problems with pests or diseases.But there are ways to control these naturally.I use floating row covers or in a serious problem a natural copper/sulfur fungicide and there are natural pest controls.
To keep ear worms out of corn either a few drops of mineral oil or a tobacco water solution will make for pest free corn,squirt into the silk when forming.
We are going to have a bigger problem if we kill off the honey bees and lose our pollinators.
I saw a film on an area in China were the fruit has to be hand pollinated because there are no bees left.
Excess phosphorus run off also causes algae blooms in water.
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I am the dust that dances in the light. - Rumi