Adapting Integrated Pest Management for Weeds in California Orchards
Integrated pest management is a framework for helping farmers use knowledge of weed biology and agroecology to create pest management programs that are less reliant on pesticides. It is imperative that weed scientists engage with other pest management and agricultural scientists to create integrated management solutions that are specifically attuned to each cropping system context. Chapter 1 expounds on these arguments. In this vein, this dissertation examines integrated pest management as it can be applied to weed biology and weed management ecology in nut orchard cropping systems in Central California. Chapter 2 focuses on the reproductive biology of field bindweed (Convolvulus arvensis L.), a perennial weed species that is pernicious in California cropping systems, especially young orchards. We evaluated time to flowering and biomass in field and potted plant experiments in response to orchard weed management practices that selectively affect aboveground and belowground field bindweed development. We found that management practices that affect field bindweed roots, such as systemic herbicides, can delay flowering reliably by over a week, which can have practical implications for planning repeated weed management actions. Chapters 3 and 4 focus on a series of experiments implementing weed-suppressing cover crops in orchards. We found that multifunctional cover crop mixes emerge more consistently than mixes containing functionally-similar species, and we also found that weed-suppressing cover crops can be successfully managed at a range of management intensities, especially with a timely cover crop planting. Weed scientists have a continued responsibility to develop integrated management programs that advance agroecological sustainability, and these results could increase the efficiency of field bindweed management and boost adoption of multispecies cover crops in orchards.