Effects of pest and soil management systems on potato diseases

Abstract

Long-term cropping systems research is important in order to reduce production costs, to control crop pests, and to optimize the sustainability of agro-ecosystems. Soil amendment use, improved disease management practices, and careful cultivar choice are some of the potential components for improving potato production systems. This research was conducted in long-term cropping systems plots in order to evaluate the impact of soil amendments, pest management practices, and cultivar on foliar and soil-borne potato diseases and to assess the relationships of soil and pest management practices to disease levels and soil microbial activity. Fungicide applications for management of foliar diseases varied between the pest management systems (e.g., biological, reduced input, and conventional). Incidence of potato foliar diseases was quantified five times during the cropping season. The impact of soil amendment and pest management practices on soil microbial activity and tuber-borne diseases was also investigated. Low incidences of foliar and selected soil-borne diseases were recorded. Disease levels varied between years, cultivars, pest management, and soil amendments. Significant differences between cultivars were detected for early blight, white mold, and black dot. The cultivar Superior had higher incidence of white mold and black dot, while cv Atlantic had higher early blight incidence. Pest management system significantly affected foliar early blight incidence in 1998, but not in 1997. Pest management system did not affect late blight, white mold, or black dot incidence, or tuber disease incidence in either year. The addition of soil amendments significantly impacted tuber black dot incidences. Microbial activity responded to increasing temperature as the season progressed and was significantly enhanced by the addition of manure and compost soil amendments; however, lower disease incidence was not associated with increased microbial activity. While pest management practices were not major determinants of disease levels in these experiments, the results show that soil amendments can increase incidence of selected tuber diseases and microbial activity in soils.