Project : USDA ARS

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Research Project: Sustainable Production and Pest Management Practices for Nursery, Greenhouse, and Protected Culture Crops

Location: Application Technology Research

2025 Annual Report

Objectives
1: Develop growth models integrating light, temperature, carbon dioxide, and other environmental factors into decision-support software tools to reduce energy costs or increase yield and quality of ornamental and edible crops grown under controlled environment. 2: Develop nutritional and substrate amendment guidelines that improve crop quality and yield or reduce environmental impacts of food and ornamental plants grown in protected horticulture. 3: Develop new hydroponic and container-culture technologies that improve substrate chemical, physical, or biological properties and reduce nutritional, water, and agrichemical inputs. 4: Identify alternative control agents and develop and/or improve methods and strategies for managing pests (insects, other arthropods, and weeds) in horticultural (food and ornamental) crops through improved knowledge of pest biology, ecology, & behavior in order to reduce pesticide usage.

Approach
Ornamental, nursery, and protected culture crops represent about one-fourth of the farm gate value of all specialty crops, and about 15% of the total value of U.S. crop production (USDA NASS Horticultural Crop Census 2014). Production value of nursery and greenhouse crops was estimated at $19 billion in 2013 (USDA NASS Horticultural Crop Census 2014). This project brings together the expertise of USDA-ARS research scientists with cooperators at other universities to focus on ornamental, nursery, and protected culture research. The project is a science-based, outcome-driven, economically motivated program that is already assisting growers in improving the quality of their food and ornamental crops. This project will continue to further our knowledge base in protected culture crops by: 1) integrating light, temperature, carbon dioxide, and other environmental parameters into growth models that enhance decision support in greenhouses and controlled environments, 2) continue developing silicon and other substrate amendments to enhance crop quality and mitigate biotic and abiotic stress, 3) engineering substrates to improve nutrient and water use efficiency, and 4) developing novel management strategies for insects and weeds that integrate knowledge of pest biology with cultural practices and management tools. This project integrates the mission and expertise of the Application Technology Research Unit with other researchers in disciplines critical to the overall success of the project.

Progress Report
This is the final report for this project which terminated in January 2025. See the report for the replacement project, 5082-30500-001-000D., “Climate-smart, Adaptive, and Resilient Production and Pest Management Practices for Nursery, Greenhouse, and Protected Culture Crops” for additional information. Objective 1: Research on plant responses to elevated CO2 and temperature was conducted. It was found that high CO2 and temperature caused some plant species to bend their leaves upward, reducing light capture and overall growth. This phenomenon was more pronounced in species with compound leaves. Photosynthetic response curves for culinary herbs and leafy greens were added to the publicly-available software tool PhotoSim. Improvements were made to the publicly-available software tool Virtual Grower 4 to enhance the accuracy of greenhouse heat balance calculations. Instrumentation was set up to collect multi-year solar spectrum and weather data. Continued improvements were made to the design and prototype of a near-field radiometer used to characterize the spatial distribution of horticultural lighting. Objective 2: Research on silicon fertilization guidelines for protected horticulture crops continued. Increasing the percentage of rice hulls in a soilless substrate increased foliar accumulation of silicon in strawberry plants. Preliminary data indicated that silicon may be beneficial in mitigating chilling injury in some culinary herbs. The impact of the ammonium:nitrate ratio on strawberry stock plant management and daughter plant production was evaluated. The number of stolons (i.e., the aboveground stems that new “daughter plants” form on) and daughter plants increased with higher nitrate levels. Data from studies on carbon source blends and sulfur supplementation impacts on anaerobic soil disinfestation were analyzed. Experiments on the ability of soilborne plant pathogens to recolonize soils treated with anaerobic soil disinfestation were concluded. Objective 3: Research on nitrogen aqueous and gaseous emissions and ornamental crop growth using coarse bark continued. Iron sulfate amended and unamended coarse bark within stratified systems was investigated. Extensive on-farm field trials and controlled studies were conducted to validate the effect of fertilizer placement on crop health and nutrient leaching. Conventional water quantity and quality data were collected at two Ohio nurseries. Nitrogen, phosphorus, and pesticide concentration and subsequent treatment efficacy were completed in 2022. Experiments with hydroponically-grown tomato plants infected with Fusarium oxysporum f.sp. lycopersici were completed to determine if biostimulants could reduce disease severity. Hydroponic tomato trials with supplemental biological control agents and chitin or chitosan biostimulants were completed to determine if the combination of biological control and biostimulants would reduce Fusarium wilt damage. Objective 4: Research was conducted to compare the influence of drought stress vs. flood stress on predisposing ornamental trees to ambrosia beetle infestations. Wood-boring ambrosia beetles are destructive insect pests of horticultural tree crops, especially in the eastern U.S. Flood stress induced the emission of ethanol, attracting the beetles. Field research continued to test a proprietary compound for reducing the attraction and colonization of ambrosia beetles. Feeding by adult red-headed flea beetles causes aesthetic damage and reduces marketability of ornamental plants and reduces yield in cranberry production. Within the past 10 years, ornamental plant nurseries in the eastern U.S. have increasingly reported losses due to damage by red-headed flea beetles. Identification of attractants and visual cues for red-headed flea beetles would provide growers with an efficient monitoring tool to determine whether insecticide treatments are needed to prevent damage. Currently, nursery growers use broad-spectrum insecticides for management purposes, and spend about $700.00 per acre per year on insecticides and labor for managing red-headed flea beetles. Monitoring techniques for red-headed flea beetles were tested, but no suitable devices were found. Research continued to address fungus gnats affecting the production of gourmet oyster mushrooms. Genetic analyses were used to identify the fungus gnats collected at cooperating farms across the U.S. Genetic detection assays were developed for two pathogens causing tomato corky root rot. Research was conducted to evaluate the repellent activity of three plant-based essential oils and a formulation of an entomopathogenic fungus against fungus gnats. The selected plant-based oils exhibited repellence against fungus gnats, but the formulation of entomopathogenic fungus was not repellent.

Accomplishments
1. Discovered that Iron sulfate reduces phosphate leaching from container-grown crops. Leaching of nutrients from container- grown crops causes profound environmental problems related to soil and water quality. Leaching of phosphorus is especially problematic, causing toxic algal blooms in many water bodies throughout the U.S. ARS researchers from Wooster, Ohio, found that using iron sulfate, a common soil fertilizer, will absorb and retain phosphorus in the container substrate and prevent its leaching. This simple approach reduced phosphorus leaching 88% to 97% without causing adverse effects on crops. This provides growers with a simple and affordable amendment to their growing media that is easy to incorporate into existing production practices.

2. Seasonal activity of exotic ambrosia beetles dominates that of native species. Ambrosia beetles are destructive wood-boring pests of horticultural trees, especially in the eastern U.S. Infestations can lead to branch dieback and tree death. ARS researchers characterized the seasonal activity of exotic and native ambrosia beetles to help growers schedule preventive management tactics to protect vulnerable trees. Exotic species initiated their dispersal flight earlier in the spring than native species, and they actively dispersed for a longer duration during spring and summer than native species. Across 4 years of trapping, a total of 145,882 ambrosia beetles were captured, of which only 622 were native species. Captures of exotic ambrosia beetles were 341 times greater than native species. The flight activity of a newly introduced species of ambrosia beetle, Ansiandrus maiche, is initiated later in spring than that of other exotic species, which increases the risk of infestation for tree growers. These results provide insight into the invasion success of ambrosia beetles and will aid in predicting and monitoring key species.

3. Discovered that cyanobacterial toxins hinder crop photosynthesis and growth. Many crops grown in fields, nurseries, or greenhouses are irrigated with freshwater from ponds and lakes. These freshwater sources may develop an overabundance of algae during the summer. Some algae produce toxins that make the water unsafe for humans and plants. ARS researchers in Toledo, Ohio, in collaboration with the University of Toledo, discovered that irrigating corn and lettuce plants with water containing high levels of intact algal cells, burst algal cells, or purified toxins all stunted plant growth. Additionally, they determined that stunted plant growth occurred because the toxins targeted the process of photosynthesis. This suggests that the common practice of filtering irrigation water before use in greenhouses and nurseries will not sufficiently remove algal toxins from the water before applying it to a crop. These findings will guide the development of new protocols to treat irrigation water containing harmful algal blooms. The findings will also help researchers identify strategies that can reduce the negative effects of irrigating crops with water containing harmful algal toxins. Collectively, this will benefit farmers and boost the productivity of U.S. farms.

4. Developed spray-induced gene silencing biopesticide. Across all test conditions, the dsRNA-treated plots showed a significant decrease in Disease Severity Index compared to untreated plots throughout the growing season. Additionally, disease progress indicated a substantial reduction in infection rates among treated plants. These findings suggest that sprayable RNA could be an effective strategy for managing white mold, boosting crop yields, and serving as sustainable biopesticide for the growers.

5. Developed mycovirus-based biopesticides for white mold control. Field crops sprayed by the SlaGemV1 viral particle filtrate showed a significantly reduced area under the disease progress curve compared to water control plots (p < 0.03). The data suggests mycovirus is an effective biopesticide that adds to the toolbox of integrated pest management for the growers.

U.S. DEPARTMENT OF AGRICULTURE

Application Technology Research: Wooster, OH