Summary
Effects of three tillage systems, three crop rotations and fungicide applications were evaluated on diseases of barley, wheat, canola, and pea at Melfort, SK., from 1994-1998.
During these years, reduced tillage did not increase crop losses due to disease.
Four-year rotations with higher proportions of broad-leaved crops and more crop diversity (canola, pea, flax, and barley) had higher yields than rotations with fewer broad-leaved crops and less crop diversity (i.e. canola, wheat, barley, barley).
These rotations did not influence the incidence or severity of Septoria leaf blotch of wheat, net blotch of barley, the incidence of Sclerotonia, stem rot, and blackleg of canola, or the severity of Mycosphaerella, blight of pea.
Fungicide application of propiconazole on Harrington barley decreased foliar disease severity and increased yield by 23%, seed weight by 13%, and kernel plumpness by 25%.
Application of azoxystrobin decreased foliar disease and increased pea yield by 29%, and seed weight by 7% for the pea cultivars Express and Highlights.
Foliar disease severity on AC Taber wheat was reduced by application of propiconazole in 2 of 4 years, but the yield response was very inconsistent.
AC Excel canola had inconsistent disease and yield response to application of propiconazole and benomyl, but the level of Sclerotonia stem rot and blackleg was low in all years.
These results indicate that reduced tillage will not result in significantly higher levels of disease that require fungicide input to maintain yield.
Moving from a cereal-based rotation to more diverse, broad-leaved based rotations improves the yields of cereals. However, regardless of tillage or rotations, higher yields may be obtained in barley or pea with fungicide for the control of leaf spot diseases in susceptible cultivars.
