Impact of agronomic practices and environment on diseases of wheat and lentil in southeastern Saskatchewan

Abstract

. 2000. Impact of agronomic practices and environment on diseases of wheat and lentil in southeastern Saskatchewan. Can. J. Plant Sci 80: 917-927. To determine the effect of tillage and rotation on plant diseases, their severity and prevalence were monitored on spring wheat, lentil, and field pea grown in rotation with zero and conventional tillage at Indian Head, SK, from 1992 to 1995. Root disease severity of wheat was less under zero tillage than conventional tillage, but leaf spot severity was unchanged. Incidence of the causal agents from roots was variable, such that Fusarium spp. were higher under zero tillage than conventional and Bipolaris sorokiniana was lower. Pyrenophora triticirepentis was the only foliar pathogen more prevalent under zero tillage than conventional. Rotation did not affect the pathogens causing root disease. However, the rotation of canaryseed-sunola-wheat-lentil had higher disease severity and levels of Septoria tritci on wheat compared with wheat-canola-wheat-lentil or wheat-pea-wheat-lentil. Neither crop rotation nor tillage practice had a measurable impact on lentil diseases, but epidemics of Ascochyta lentis and Botrytis cinerea were most severe in treatments with the densest plant stands. Multivariate analyses explored trends of tillage, rotation, and environment over years demonstrating that regardless of tillage or crop rotation practices, the annual environment was the most important factor limiting the severity of disease and the prevalence of causal agents in the complex. Les affections racinaires du blé étaient moins graves en régime SD qu'en régime TC, mais on ne notait pas de différences comparables pour les taches foliaires. La fréquences des pathogènes prélevés sur les racines était variable, celle des Fusarium spp., par exemple, était plus forte et celle de Bipolaris sorokiniana plus basse en régime SD. Pyrenophora tritici-repentis était le seul pathogène foliaire plus abondant en régime SD. Le type de rotation des cultures n'avait pas d'effet sur les pathogènes racinaires, bien que la rotation alpiste des Canaries-sunola-blé-lentille manifestait un niveau plus élevé de gravité et d'étendue des infections à Septoria tritci sur le blé que les rotations blé-canola-blé-lentille ou blé-pois-blé-lentille. Ni la rotation ni le régime de travail du sol n'avait d'effet mesurable sur les maladies de la lentille, mais les épidémies d'Ascochyta lentis et de Botrytis cinerea étaient le plus graves dans les cultures présentant une plus forte densité de peuplement. Les analyses multivariées de l'évolution des pratiques du travail du sol, des rotations et des conditions du milieu au cours des années ont permis de constater que ces dernières constituent le facteur limite le plus important de la gravité des maladies et l'abondance relative de tel ou tel pathogène dans les cultures.

The impact of crop rotation and N fertilizer on common root rot of spring wheat in the Brown soil zone of western Canada

“…These findings agree with those reported by Bailey et al (2000) for the more humid southeastern region of Saskatchewan. Our observation that disease severity was highest in 2001 agrees with reports that common root rot is favoured by high temperatures (Wiese 1987).…”

“…in winter wheat roots, although Conner et al (1996) showed that flax had to be grown for at least 2 yr to reduce common root rot in subsequent spring wheat crops. In contrast, Bailey et al (2000) found in a study conducted in southeast Saskatchewan that rotations with noncereal crops did not affect root rot severity in spring wheat or the pathogens isolated from affected roots.…”

“…However, these two fungi have been reported to affect wheat plant growth (Bhalla et al 1984), with M. bolleyi shown to suppress seedling emergence of cereal and noncereal crops (Black and Brown 1986). Both fungi were also commonly isolated in other studies of underground tissue (either roots or subcrown internodes) of spring and winter wheat (Sturz and Bernier 1989;Bailey et al 2000;Fernandez and Jefferson 2004).…”

Influence of subsoiling on direct-seeded cereals in southeastern Idaho

“…In another Canadian study, no consistent differences in common root rot ratings were found when wheat was grown under conventional tillage and minimum tillage (Conner et al 1987). Bailey et al (2000Bailey et al ( , 2001 found that no tillage was associated with reduced populations of B. sorokiniana and increased incidence of Fusarium spp. in roots.…”

“…in roots. Most of the Fusarium spp., such as F. equiseti and F. acuminatum, identified in their plots are considered to be weak pathogens or saprophytes (Bailey et al 2000). Fewer than 20% of the species identified were serious pathogens of cereals, such as F. culmorum (Bailey et al 2000).…”