Organic versus Stainable
The simple truth is that organic food is a luxury item. When you eat an apple produce without pesticides, several other apples that got bugs where thrown away. The only rational way to reduce pesticide usage is to get over having an occasional worm in your corn. When you see that, it means no pesticides where used - toss the worm out, cut out the bad part and eat it. That what people who live on farms do.
On the other hand, the way that industrial agriculture uses pesticides and herbicides is a nightmare. Consider the herbicide in Roundup. Crops are genetically engineered to be resistant to it, then mass amounts are sprayed all over the field to kill weeds. Remember DDT? It was applied by the ton, everywhere, killing every insect it touched. It didn't degrade and ended up being concentrated in animals high on the food chain, where it caused severe problems.
So it was banned, completely....which led to millions of people dying from malaria. DDT soaked mosquito nets, and DDT spray inside a home, on the walls, dramatically reduces cases of malaria, as mosquites almost always light on these surfices before biting. There is no harm to the environment from this usage. Using DDT like this is rational and sustainable, but not organic.
Sustainable agriculture aims to improve the land that is used, so that it may be used for farmland indefinitely, which harm to the local ecosystem. Old school farming is a war against nature, an attempt to erase a natural ecosystem and create a highly artificial system that is designed to maximize production. As an example, a while back I was trying to find a way to stop a particular pest from eating my roses. I studied the pest and found a pesticide that would kill without killing every other bug, and a time to apply it when it would be most effective. My father was curious, and said "Why don't you just use this, and kill all the damn bugs?" I thought about the tiny praying mantis I'd seen while sniffing out the pests...It's a different way of thinking. In sustainable agriculture, you guide and modify the ecosystem - guide it towards productivity. You NEVER win when you fight nature. So we don't - we incorporate it and use it.
Sustainable agriculture does use pesticides. We use them sparingly and very selectively, using scientific research to be sure we're not damaging the local ecosystem. Organic agriculture, for instance, uses copper as a fungicide, because copper is 'natural'. Copper is lethal to fungi, algae and snail, kind of like how mercury and arsenic are lethal to mammal, and it doesn't go away. Throw a penny in an aquarium full of algae and it all dies, forever, along with all the snails and the only way to get it out is to start over. I might use a copper spray, for instance, to control tomato blight, but I know when to use it and how much so it doesn't cause problems. Likewise, if my crops are infested with caterpillars, I might use a pesticide that kills only caterpillars (there is one), and apply it with a handsprayer only where needed. I might use chemicals to improve soil that has been tormented by decades of traditional farming, or I might use compost - which ever is best for the situation.
The result is food you can afford, grown in a way that is environmentally sound. There are no standards for sustainable food - creating such a huge, wasteful bureacracy would defeat the purpose. The people who grow food this way are highly skilled and educated professionals. The money, the investment, is in these people, in the beginning, rather than in expensive chemicals or wasteful processes.
For this to work, consumers need to be a part of it. Get over pretty, perfect vegetables. For every one you buy, others were grown and disgarded. Like thely plant has been selectively bred for appearance and shelf live for decades, rather than taste and nutritional value. Here, for instance, is a picture of an apple, directly from the tree. It's green and tart and better tasting than anything you can buy. It also has brown patches on its skin, from a harmless fungus. That's a good sign - it means the apple was produced in a functioning ecosystem, not in an artificial farm. Eating food like this is good for you, we'll talk about that later in the Hygiene Hypothesis.