Crop rotation will always be the surest way to control root diseases, but continuous crop monoculture can also bring about the control of some root diseases. Read about the remarkable story of take-all decline with continuous monoculture of wheat.
The Centerpiece of Plant Disease Control.
Biological Control includes the use of natural or modified organisms, genes or gene products to reduce the effects of undesirable organisms (insect pests, plant pathogens, plant parasitic nematodes, weeds) and to favor desirable organisms such as crops, trees, animals and beneficial insects and microorganisms. (National Academy of Sciences Report of the Research Briefing Panel on Biological Control in Managed Ecosystems, National Academy Press, 1987.)
This broad concept of biological control is adopted here for plant pathogens. It includes the use of cultural practices such the rotation of crops to allow time for the natural resident soil microbiota to lower the population of the soilborne pathogens of one crop while growing a different and unrelated crop. It also includes the use of genes and gene products whether delivered through host plant resistance or plant-associated microorganisms.
Biological control is contrasted with physical control, which includes steam, soil solarization, flooding, desiccation, electrocution, or physically separating the pathogen from the plant by meristem culture. Chemical control includes the use of synthetic and natural chemical products to inhibit or kill pathogens.
Biological control attained through its many applications and practices should be the centerpiece of plant disease control, while taking advantage of opportunities for physical control judiciously combined with chemical control.