An alternative to pesticides

About a week ago we went to a thrift store. As usual, I looked through the books. Normally I don't find anything, but once in a while I discover something worth buying. Last week was one of those times. I found a gardening book about pesticides and herbicides by a University of Minnesota professor. He examines the various options, organic and synthetic, to control garden problems, be they weeds or bugs. He isn't against synthetics, but he very firmly believes that whenever possible, organic methods are best. But, he also believes the following, which has been my experience over the years as well:

From nematodes to insect diseases, a plethora of avenues exist to treat for insects without resorting to synthetic or organic insecticides. But why bother with insect control at all if you don’t have to? One of my favorite ways to deal with pests is by ignoring them and instead concentrating on getting plants to grow as vigorously as possible. A healthy and growing plant is better able to tolerate insect damage than one that isn’t and often eliminates the need for insecticides.—The Truth about Organic Gardening, 66

He goes on to say that a plant can lose as much as 1/3 of its leaves and still be fruitful.