Soil & Tillage Research 72 (2003) 169–180 Suppressing soil-borne diseases with residue management and organic amendments K.L. Bailey a,∗ , G. Lazarovits b a Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, Sask., Canada S7N 0X2 b Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, 1391 Sanford Street, London, Ont., Canada N5V 4T3 Received 25 November 2002; accepted 3 March 2003 Abstract Changes in agricultural practices with time have led to a decline in soil structure and with it, an increase in soil-borne plant diseases. Agricultural practices such as incorporating organic amendments and managing the type and quantity of crop residue, have a direct impact on plant health and crop productivity. Soil management practices involving tillage, rotation, and burning will impact the amount and quality of organic matter that is returned to the soil. These practices influence pathogen viability and distribution, nutrient availability, and the release of biologically active substances from both crop residues and soil microorganisms as illustrated by the model system of Cochliobolus sativus on the development of common root rot in cereals. The application of organic amendments, manures and composts that are rich in nitrogen, may reduce soil-borne diseases by releasing allelochemicals generated during product storage or by subsequent microbial decomposition. The modes of action for disease suppression are elucidated for a number of diseases including verticillium wilt and common scab of potato. Developing disease suppressive soils by introducing organic amendments and crop residue management takes time, but the benefits accumulate across successive years improving soil health and structure. Crown Copyright © 2003 Published by Elsevier Science B.V. All rights reserved. Keywords: Soil-borne diseases; Tillage; Rotation; Residue; High nitrogen amendments; Manure; Compost 1. Introduction For centuries, farmers have consciously and uncon- sciously manipulated the ecology of the soil by the addition or depletion of organic matter. Organic mat- ter is known to affect soil aeration, structure, drainage, moisture holding capacity, nutrient availability, and microbial ecology (Davey, 1996). Incorporating or- ganic amendments and managing crop residues (type and quantity) have a direct impact on plant health and ∗ Corresponding author. Tel.: +1-306-956-7260; fax: +1-306-956-7247. E-mail address: baileyk@agr.gc.ca (K.L. Bailey). crop productivity. Crop rotations consisting of wheat, beans or legumes followed by either a fallow period or a green manure were frequently used in the times of ancient Greece and Rome (Karlen et al., 1994). Ma- nures and by-products of the seafood and livestock industries have been used by growers to maintain pro- ductivity of agricultural soils for millennia (Davey, 1996; Barker et al., 2000; Lazarovits, 2001). How- ever, after World War II, many farming systems in the developed world abandoned the use of crop rotation and animal manures for shortened rotations, monocul- ture cropping, intensive tillage, synthetic fertilizers, and pesticides (Katan, 1996). The living components in soils require carbon as an energy source, but there 0167-1987/03/$ – see front matter. Crown Copyright © 2003 Published by Elsevier Science B.V. All rights reserved. doi:10.1016/S0167-1987(03)00086-2