Increasing the frequency of canola and pea in rotations

Abstract

Economic constraints can force producers to grow high value crops such as canola and peas more frequently in a rotation than is currently recommended for disease control. A study was initiated: to examine the impact of cultivar selection and pest control technologies on disease management, to determine how this impacts on recommendations for frequency of pea and canola in rotations, and to evaluate the influence of preceding crops on yield and cost of disease control. The study is located at Scott, Saskatchewan in the semi-arid prairie and at Melfort, Saskatchewan in the sub-humid Parkland. Peas and canola are grown continuously to once every two, three or four years in rotations with each other, wheat and flax. The pea cultivar (Highlight) has powdery mildew resistance, and the canola cultivars are a hybrid, with herbicide tolerance and moderate blackleg resistance (Invigor 2153), and a blackleg susceptible, open-pollinated cultivar (Westar). The experiment at each site is designed as a four replicate split-plot factorial; main plots consist of crop rotations and crop cultivars as factors with each phase of each rotation appearing every year. Each main plot is split for fungicide application (Azoxystrobin for blackleg of canola and Mycosphaerella of peas, vinclozolin for sclerotinia of canola). In this first year of the study there was no rotation effect. Fungicides were effective at reducing the severity of mycosphaerella blight of peas at Scott and increasing yields at both locations (12.4% at Scott and 15.8% at Melfort). Blackleg incidence was reduced with fungicide application at Scott but not Melfort. Yield of either cultivar of canola was not increased by fungicide application and differences in yield between Invigor 2153 and Westar were not detected at Scott.