- Agronomic: canola, wheat
- Pest Management: biological control, chemical control, cultural control, integrated pest management
- Production Systems: organic agriculture
The wheat stem sawfly, Fusarium crown rot, and grassy weeds form an interacting multi-trophic pest complex affecting farmers across the Northern Great Plains. Our goal was to develop a framework for modeling and analyzing data within the context of a total-system approach to pest management. We conducted field studies to evaluate the relative importance of crop variety, seeding rate and weed management approach on insect pests, plant pathogens and grassy weeds. While our results indicated complex interactions in the response of these pests to management, our modeling allowed us to pinpoint first principles of a total-systems approach to pest management.
The Northern Great Plains is a leading producer of small grain, pulse and oilseed crops and has strong potential for low-intensity organic agriculture (USDA ERS, 2011). However, the high commodity specialization (i.e. wheat) within conventional agriculture has resulted in vast monocultures and an influx of a specialized pest complex that compromises the robustness, resilience and environmental integration required in sustainable farming systems (Gan et al., 2010; NRC, 2010). In this region, wheat stem sawfly (Cephus cinctus, WSSF hereafter), Fusarium crown rot (Fusarium hereafter) and grassy weeds, represented in this project by Bromus tectorum (downy brome or cheatgrass, cheatgrass hereafter), form an interacting multitrophic pest complex which is a major burden to wheat cropping systems. Lack of viable pesticides for WSSF and Fusarium and the existence of herbicide resistant weed biotypes challenge the chemically-based, single-pest control paradigm. Moreover, each one of these pest groups responds differently to management practices, and contradictions among current single-pest recommendations may, in turn, lead to undesirable consequences (Shennan, 2008).
For dryland agriculture to meet increasing demands for yields, while sustaining the environment’s economic, social and ecological services, it is necessary to achieve a systems-level understanding of the linkages among biophysical processes, human activities and socioeconomic goals (Robertson et al., 2008). To facilitate such understanding, our main goal was to develop a framework for modeling and analyzing data within the context of a total-system approach to pest management (Lewis et al., 1997). To achieve our goal, we formed a multidisciplinary team composed of entomologists, plant pathologists, weed scientists and agronomists. To encompass a range of environmental conditions, we conducted our research in different locations across the Northern Great Plains.
Objective 1. Quantify interactions among wheat stem sawfly, Fusarium and grassy weeds in their joint impact on crop yield and in response to simple control practices, such as seeding density, herbicide management approach and crop variety.
Objective 2. Develop a predictive computer model to assess the relative importance of seeding density, herbicide management approach and crop variety on crop yield and the population dynamics of wheat stem sawfly, Fusarium and grassy weeds.
Objective 3. Develop and deliver an education and extension program to increase producers’ knowledge base on the ecological basis of multi-pest management strategies.