The field incidence of pea root rots in southwestern Ontario averaged 26%. The root rot complex severely curtailed green pea yield. The etiology of this complex was resolved by an extensive field survey and numerous isolations. A total of 782 fungal isolations were obtained from 465 samples collected from 33 pea fields. The isolations yielded Fusarium solani f. sp. pisi, F. oxysporum f. sp. pisi, Aphanomyces euteiches and Pythium spp. in 7:4:1:1 frequency. The ratio of races 1 and 2 in the F.oxysporum isolates was 7:4. The disease severity caused by F. solani (root rot), F. oxysporum (wilt), Pythium and Aphanomyces averaged 3.2, 8.7, 2.6 and 4.0, respectively, on a 0-9 scale. Based on this information, a disease damage index (DDI) was developed to rank the relative importance of these four root rots. the DDI of a root rot equals the total amount of root rots (26.5%) x the frequency of occurrence of each fungus x the severity of disease caused by each fungus. The DDIs for F. solani, F. oxysporum, Pythium spp. and A. euteiches, were 45, 71, 5 and 8, respectively. Therefore,  usarium wilt is the most damaging disease followed by Fusarium root rot. While Pythium and Aphanomyces root rot are of minor importance. Based on the etiological and biological findings, an integrated control program has been developed. The program includes: (a) development of a new seed treatment formulation; (b) trial and selection of disease resistant cultivars; (c) formulation of suitable herbicide combinations; (d) development of a soil indexing procedure; (e) improvement of tillage practices; (f) adoption of interseason green manure crops and (g) modification of soil pH. The success of this integrated disease control program has brought pea root rot under control.