Project : USDA ARS

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Research Project: Optimizing and Stabilizing Economic and Ecological Sustainability of Pacific Northwest Seed Cropping Systems Under Current and Future Climate Conditions

Location: Forage Seed and Cereal Research Unit

2024 Annual Report

Objectives
Objective 1: Identify and evaluate economical methods for sustainable pest management practices in seed crop systems that improve crop productivity, seed health, and seed lot quality by controlling historical and emerging pests. - Sub-objective 1A: Develop optimized survey and molecular detection methods for Anguina seed gall nematodes infecting ARG and OG seeds. - Sub-objective 1B: Investigate the spatiotemporal composition and environmental predictors of the aphid– YDV virus-vector system in perennial grasses grown for seed production. - Sub-objective 1C: Integrate cultural, chemical, and biological control strategies to reduce YDV disease severity and protect yield potential in grass seed production. - Sub-objective 1.D: Improve grass seed production and seed lot quality by examining cultural harvesting practices and companion cropping to minimize weed contamination. - Sub-objective 1E: Improve knowledge of arthropod pest population dynamics and integrated pest management in grass and legume seed production. Objective 2: Evaluate the effects of soil amendments, tile drainage, and conservation residue management on soil health, C sequestration potential, and biodiversity to improve/enhance ecosystem services, productivity, sustainability, and resilience to climate change. - Sub-objective 2A: Quantify and model soil C stocks on seed production systems differing in subsurface drainage, residue management, and tillage practices. - Sub-objective 2B: Using Balansa clover, evaluate how five termination methods and three termination times affect the availability of N and GHG fluxes. - Sub-objective 2C: Measure the synergistic interactions between basalt dust, biochar, and arbuscular mycorrhizal fungi (AMF) that sequester and transform atmospheric CO2 to bicarbonate in grass seed production systems. - Sub-objective 2D: Evaluate the effects of baling and flailing straw residue on weed ecology and efficacy of pre-emergent herbicide applications in grass seed production systems. Objective 3: Develop knowledge, technologies, and decision support tools that enable growers to optimize seed production for economic and ecological sustainability and resilience to weather extremes. - Sub-objective 3A: Develop WV Soil Organic C decision support tool. - Sub-objective 3B: Expand existing resources to increase the geographical and functional range of the PNW Biochar Atlas. - Sub-objective 3C: Develop decision support tools to forecast and improve monitoring of economic pests in seed crop production systems. - Sub-objective 3D: Develop an environmental-based model to predict ABG seed germinability in grass seed production systems.

Approach
The long-term aim of this project is to address high priority needs of Oregon and Pacific Northwest (PNW) seed growers by adapting and developing management practices that improve crop productivity, advance ecosystem and economic resilience, and provision ecosystem services. This aim will be met by investigating systems-level questions that fall into two broad objectives and their related subobjectives. In Objective 1, we focus on improving crop production, seed health, and seed lot quality by lessening the overall impact of pests. The research for this objective is conducted in laboratory, greenhouse, and field experiments focused on improving detection and management of priority pests, evaluating reduced pesticide application strategies, and developing pesticide resistance management plans. In Objective 2, research is focused on understanding the effects of management practices on soil health, carbon (C) sequestration potential, and biodiversity to enhance ecosystem services, productivity, sustainability, and resilience to extreme weather. This objective is met with laboratory, greenhouse, and field experiments that examine the influence of management practices and soil amendments (tile drainage, residue management, tillage, cover cropping, biochar, and basalt dust) on biogeochemical cycling and microbial population dynamics. The aim of Objective 3 is to synthesize the knowledge acquired and published in peer-reviewed journals in Objectives 1 and 2 to develop innovative decision support tools, storyboards, and other materials that clearly guide farmers towards the science-based practices that achieve balance between ecosystem and economic sustainability. The tools from this objective include web-based tool kits, models, and agronomic measures used to control pests and weeds, and to apply soil amendments. In general, these approaches aim to identify key interactions between genetics, environment, and management that simultaneously reduce farm inputs and improve ecosystem services by identifying and quantifying tradeoffs.

Progress Report
This report documents FY 2024 progress for project 2072-21600-001-000D, “Optimizing and Stabilizing Economic and Ecological Sustainability of Pacific Northwest Seed Cropping Systems Under Current and Future Climate Conditions”, which began in September 2023. National and international markets depend on the production of high quality, high yielding grass, forage, and cover crop seeds. The Willamette Valley (WV), located in western Oregon, is renowned for the production of cool-season grass seed and a diverse array of other seeds for forage, food, and cover cropping (CC) applications. Seed producers in the region; however, are facing emerging challenges that decrease productivity, including a diminished arsenal to control pests, pathogens, and weeds; the degradation of soil health; and a changing climate. Recognizing that trade-offs exist between optimization of crop production and ecological sustainability, ARS scientists in Corvallis, Oregon, are quantifying and identifying best management practices that provide high levels of ecosystem services while optimizing economic goals. In 2024, significant progress was made on all three objectives and sub-objectives outlined in the project narrative. Disease management in grass seed crops is challenging due to the perennial nature of the crops, limited labeled pesticides, and strict phytosanitary requirements. Improved detection methods and integrated management strategies are needed to reduce disease. In support of Sub-objective 1A, a regional survey was initiated to optimize detection of Anguina seed gall nematodes in grass seed cropping systems. Early detection of these nematodes provides better assessment of risk of export rejection. A new molecular protocol was developed and validated for Anguina spp. identification. Comparisons of this protocol to manual nematode extraction indicate increased identification capacity with this method. Accurate and timely identification of these nematodes will allow growers to make informed decisions on exporting seed from infested fields. Two years of survey have been conducted at this time, indicating early spring and autumn are the most critical timepoints for capturing seed gall nematode activity in the field. In addition to this survey work, laboratory and greenhouse-based evaluations of potential management strategies are underway. Aphid-transmitted viruses are widespread in the grass seed production system and have been associated with reduced yield potential. In support of Sub-objective 1B, statewide monitoring efforts have investigated the composition and spatiotemporal distribution of the aphid-yellow dwarf virus (YDV) complex in grass seed crops to inform predictive modeling efforts. Diversity of YDVs have been seen throughout the WV as compared to eastern and central Oregon. For Sub-objective 1C, a small plot field trial evaluating perennial ryegrass management factors (insecticide timing, nitrogen rate, and genetic background) has been planted. Year one results indicate increased harvest potential in plants with lower nitrogen inputs and fall or spring insecticidal sprays. This provides growers with cost-effective, integrated management strategies for this pest complex. In support of Sub-objective 1D, three experiments are taking place in Corvallis, Oregon. The first experiment was initiated in September 2023 and consists of forage type tall fescue sown in combination with nine legume companion crops. Preliminary data have provided information on weed suppression, legume disease susceptibility, as well as herbicide safety and efficacy against problematic weeds in western Oregon, which will lead to refining the experiment in future seasons. A second experiment consisting of sowing perennial ryegrass in combination with club wheat began in September 2023 and is ongoing with alternative harvesting treatments scheduled for July 2024. A third experiment consisting of alternative harvesting practices of a second-year stand of tall fescue will also take place in July 2024. Under Sub-objective 1E, statewide monitoring of priority pests in grass seed crops has been conducted to develop or revise current phenological models and investigate environmental risk factors associated with pest outbreaks on commercial farms. Laboratory research has been conducted to revise regionally specific phenology models for noctuid pest species in grass seed crops. Developed phenology models have been shared with stakeholders using an interactive online platform (Sub-objective 3C). Also, in support of Sub-objective 1E, laboratory and field populations of Noctua pronuba (winter cutworm moth) are currently being evaluated to determine the female sex pheromone to be used for the development of a commercial lure to improve monitoring efforts of this international pest. For Objective 2, ARS scientists in Corvallis, Oregon, convened a group of grass seed producers to inform and implement an experimental framework for understanding how management practices and soil properties drive the accumulation of soil carbon (C). Three management practices, tile drainage, residue return, and tillage were selected as potential practices that influence soil C stocks. In support of Sub-objective 2A, fields managed under artificial and natural drainage were selected and sampled. All soil analyses (soil organic C and N, soil pH, bulk density, soil particle size analysis, microbial biomass C and N, particulate organic matter-C and mineral-associated organic-C) have been completed. On going data analysis will determine how these practices influence soil C dynamics. To model changes in soil C that are potentially induced by management practices, ARS scientists in Corvallis, Oregon, received partial training on the DayCent model. Also, in support of Sub-objective 2A, straw decomposition as measured by carbon dioxide release over an 84-day incubation are on-going. Results to date (day 56) indicate greater carbon losses in long-term full straw load fields than baled fields, indicating a priming effect in fields under full straw return. Further biological (e.g., microbial biomass and DNA sequencing) and chemical (pH, soil organic C and nitrogen content) will help explain observed differences in these long-term management strategies and influence on C flow and storage. Greenhouse gas (GHG) emissions have been collected in tile drainage fields during winter (dormant) and spring (growing season). Cumulative carbon dioxide flux was not significantly different between tile management practices, but nitrous oxide flux was greater in untiled fields compared to fields with new or old tile. These data suggest that tiling has the benefit of lower nitrous oxide fluxes, a potent GHG with 273 times the global warming potential as carbon dioxide. Management practices also influence soil nitrogen and GHG emissions. To evaluate the effect of cover crop termination type and timing in support of Sub-objective 2B, cover crop trials were established using Balansa clover as a cover crop of interest. GHG fluxes of carbon dioxide and nitrous oxide and nitrogen release during the decomposition phase (i.e., post termination) are in progress. Under Sub-objective 2D, perennial ryegrass and tall fescue research field plots were established in September 2023. These plots will be harvested in July or August 2024 and pre-emergent herbicide trials will take place in September or October 2023. In support of Objective 3, ARS scientists in Corvallis, Oregon, began collecting foundational field, pest, and biochar data to develop a suite of decision support tools that inform either pest management or biochar application. Scientists collected information regarding management practices across several fields to support the development of a soil health management index in support of Sub-objective 3A. For Sub-objective 3B, ARS scientists in Corvallis, Oregon, collected over 30 commercially-available biochars from biochar producers. These biochars are being evaluated in a cross-location study involving ten ARS laboratories to determine the reliability of current methodologies used to evaluate biochar. Researchers will continue to collect samples over the next year to improve representation of various feedstocks, production conditions, and post-production processing methods within the biochar properties database. Under Sub-objective 3C, a decision support tool (available at: https://oregonpests-usdaars.hub.arcgis.com/pages/pest-forecasts) has been developed to share spatialized pest forecasts using real-time weather. Models and features will continue to be revised and added as research progresses (Sub-objective 1E). In support of Sub-objective 3D, annual bluegrass seed has been collected every 50 growing degree days (GDDs) up to 1,100 GDDs from a first-year stand of tall fescue located in Corvallis, Oregon, in the winters of 2023 and 2024. Preliminary data from 2023 suggest that annual bluegrass seed collected prior to 300 GDDs exhibit a lower level of germinability compared to seeds collected later in the season.

Accomplishments
1. Molecular assays provide improved seed gall nematode detection and risk assessment in grass seed crop. Western Oregon is the most important U.S. supplier of annual ryegrass (Lolium multiflorum) and orchardgrass (Dactylis golmerata) seed to the global forage industry, and seed gall nematodes (SGN, Anguina spp.) are a regulated pest in these crops, leading to over one million pounds in seed rejection at international ports in 2019 and 2020. ARS researchers in Corvallis, Oregon, demonstrated the utility of a sensitive molecular assay for the detection of SGN from plant samples, allowing for more testing labs to identify SGN in grass seed fields before shipment overseas, where a single SGN detection can lead to seed lot rejection. ARS researchers have determined the prevalence of SGN in Oregon annual ryegrass and orchardgrass seed production through field surveys using these improved detection methods. They have developed recommended sampling best practices for nematode detection from tiller samples and shared those findings at industry events and through an open access webinar. The ability to rapidly detect SGN throughout the growing season has allowed for further investigation into management strategies targeting susceptible life stages of SGN.

2. Laboratory and field research document pyrethroid resistance in clover seed weevil (Tychius picirostris) populations in Oregon white clover seed crops and provide alternative management strategies. Clover seed weevil can cause significant reductions in yield, resulting in upwards of $800 in economic losses per hectare. For the first time in Oregon, ARS researchers in Corvallis, Oregon, identified high levels of pyrethroid and low to moderate levels of organophosphate insecticide resistance. Synergistic effects were observed with oxidase and esterase inhibitors suggesting potential mechanisms of insecticide resistance development. Field assays determined optimal spray timing for new insecticides to replace pyrethroids, which, in combination with known pyrethroid resistance, will support the regulatory processes to obtain pesticide registrations. New and efficacious insecticides for clover seed weevil are more expensive; this research addressed this by determining the economic thresholds needed to warrant insecticide applications. A survey of the white clover industry (n = 42) revealed that most growers (greater than 65%) intend to stop using pyrethroids for clover seed weevil management as a direct result of this research.

3. A multilocation effort supports the development of a laboratory standard for testing biochar properties. The implementation of Natural Resources Conservation Service Conservation Practice Standard 336 has created an urgent need for standardized protocols that characterize the physical and chemical properties of biochars. In response to this need, ARS scientists in Corvallis, Oregon, organized a multi-location effort to analyze current methodology to determine if the standard procedures are accurate and reproducible. Currently, ARS scientists across ten locations located in four areas are participating in this trial. The results of this work are now being used to develop a harmonized American Society for Testing and Materials (ASTM) laboratory standard that will be adopted by industry groups and implemented in commercial analytical laboratories.

U.S. DEPARTMENT OF AGRICULTURE

Forage Seed and Cereal Research Unit: Corvallis, OR