Submitted to: Encyclopedia of Pest Management
Publication Type: Review Article
Publication Acceptance Date: 2/6/2001
Publication Date: 1/15/2002
Citation: Wilson, J.P. 2002. Crop rotations (plant diseases). pg. 172-173 in: Pimentel, D. (Ed.) Encyclopedia of Pest Management. Marcel Dekker, NY.
Interpretive Summary: Crop rotation has been practiced for thousands of years and its many benefits are well-documented, although continued research is still necessary. Diversified production systems enhance economic stability of agricultural communities, and shifting demographics increase demand for a greater variety of plant products in all regions. Evaluating compatibility of new crops in existing agricultural systems is needed. Identifying crops with allelopathic effects toward soilborne pathogens should have a high priority. Crops with known allelopathic reactions, or tailored through plant breeding to express greater levels of allelopathic compounds would allow an active, crop-mediated biological control of some soilborne diseases. The environmental benefits of rotations using perennial forage and hay grasses merit greater scrutiny. Because soil erosion and nutrient runoff is minimal in properly managed pastures, practical and economical systems using perennial forage and hay grasses should be developed. Crop rotation is one component for developing sustainable agricultural systems. Disease control based on several integrated practices provides an inherently stable buffer against losses. As use of chemical controls become limited due to legislation increasing cost, alternative methods will be required for disease control. Crop rotation is a fundamental strategy for managing soilborne diseases.
Technical Abstract: Crop rotation is the practice of growing different crops in sequence on a given field to maintain productivity. When a particular crop is consistently grown on a site, certain weeds and pathogenic microorganisms that can limit production or profitability will frequently increase. Crop rotation minimizes the populations of pathogenic nematodes, fungi, bacteria, and viruses in the soil. Rotations minimize the amount of inoculum in the soil by cultivating appropriate crops which do not serve as host to the target pathogen(s) for an appropriate length of time between susceptible crops. Crops are chosen based upon the inability of the pathogen to reproduce on them. Rotation intervals are determined by attrition of the pathogen in the soil environment. Rotations will effectively manage disease if the rate of inoculum attrition is greater than the rate of inoculum production. Several factors interact to affect the rates of inoculum production and attrition in the soil.