This book has become a standard reference for companion planting in fruit and vegetable gardens. Companion planting is the process of planting compatible plants together to encourage growth and repel destructive insects.
Some plants have odors that act as a mask to insects, confusing the insects or drawing them away from susceptible hosts. That's one of the reasons mixed plantings give better insect control than a monoculture. Other plants change the nutrient values in the soil. Very deep-rooted plants pull up minerals for shallow-rooted plants, and legumes fix nitrogen for other plants to use too.
Softcover, 6" × 9", 220 pages, revised in 1998. Interesting reading.