Location: New England Plant, Soil and Water Research Laboratory
2021 Annual Report
Objectives
Objective 1: Develop sustainable cropping systems that include effective management practices to improve soil health, crop productivity, and economic viability, and reduce soil borne diseases for food production systems of the Northeast.
Sub-objective 1.1. Develop and implement sustainable cropping systems consisting of effective management practices that maintain or improve soil health, productivity and market quality, reduce soilborne diseases, and enhance profitability for potato-based production systems.
Sub-objective 1.2. Develop and evaluate crop and soil health management practices for conventional and organic vegetable production systems to improve crop productivity, economic viability, and reduce impacts on the environment.
Approach
Our approach to building sustainable cropping systems for improving crop productivity and enhancing economic viability for food production systems in the Northeast is through the development of improved biological and cultural management practices and incorporating these into integrated cropping systems. There are many practices and amendments that have been previously identified, in ours and others research, as providing beneficial responses for these production systems. However, much research is still needed to determine the best ways to utilize and implement these practices in production agriculture. In our previous research, through long-term cropping systems studies, we determined the areas that are the most crucial constraints to productivity in potato production systems, as well as some factors that were less important. Critical constraints were water availability, soil health, and disease pressure, whereas previously studied criteria such as fertility and soil physical properties were not critical factors. Further research indicated that a specific 3-yr cropping system containing a disease-suppressive rotation crop and a small grain could maintain low disease while achieving high yield, and be profitable. In addition, a system with organic amendments added periodically could substantially increase yield and productivity. This proposed research is building directly on this previous research, further developing and refining management practices that have shown the greatest potential for reducing soilborne diseases, enhancing soil health, and improving crop yields in a sustainable manner. Management practices of particular importance include the use of disease-suppressive rotation crops, cover crops, green manures, and organic amendments. Focus will be placed on developing practical cropping systems that can be readily implemented and provide useful benefits to growers. Special emphasis will be placed on the biological processes involved and the role of soil microbial communities in developing disease-suppressive, yield-enhancing cropping systems.
Progress Report
This project consists of a series of research studies using crop and soil management practices to improve crop productivity, economic viability, and reduce diseases to build and develop more productive and sustainable cropping systems for conventional and organic food production systems in the Northeast. In this year of the project, ongoing field experiments were continued in Presque Isle and St. Albans, Maine. In our potato cropping systems research at Presque Isle, Maine, in addition to continuing to monitor enhanced cropping systems incorporating reduced tillage, cover crops, organic amendments, and disease-suppression rotation crops for improvements in crop productivity, disease suppression, and economics, cropping systems were recently modified to include an additional potato variety with improved characteristics, as well as new cover cropping treatments, for applicability and comparisons with existing systems. Field preparation, soil sampling, and planting for the 2021 field season were accomplished in May-June 2021. In our organic vegetable trials in St. Albans, Maine, soil amendment treatments and cover crop comparisons have been implemented with green bean, squash, and sweet pepper vegetable crops (planted May 2021) to determine improved management practices for organic vegetables. Characterization, analyses, and assessment of the soil microbiome in relation to numerous factors is also a feature of the project for potato and vegetable cropping systems. Data collected from 2019 and 2020 have been analyzed and demonstrate the benefits of incorporating soil health management practices into improved cropping systems. Results are being disseminated to stakeholders, and other researchers are being used to determine future directions for the research. Overall, this research provides information needed to improve crop production and sustainability for potato and organic vegetable production, leading to improved agricultural viability and rural economic vitality in the Northeast.
Beneficial soil and crop management practices, such as longer rotations, cover crops and green manures, organic amendments, and reduced tillage, may improve soil and crop health when incorporated into cropping systems, but full effects may take several years to develop. ARS researchers in Orono, Maine examined different 3-yr potato cropping systems focused on specific management goals of soil conservation (SC), soil improvement (SI), and disease-suppression (DS) compared to a 2-yr standard rotation (SQ) and a non-rotation control (PP) after 12-15 years of production for their effects on soil properties, soilborne diseases, crop production, and the soil microbiome. The SI system (with history of compost amendments) improved soil properties water-holding capacity, organic matter and nutrient contents, aggregate stability, and cation exchange capacity, relative to all other systems, as well as higher tuber yields (by 26%) and higher microbial activity (by 44%) relative to the standard system. The DS system, which included a disease-suppressive green manure rotation crop also improved yield (by 16%), had higher organic mattercontent, and increased microbial activity relative to SQ, as well as reducing soilborne diseases (black scurf and common scab) by 10-30%. The nonrotation PP system resulted in notable degradation of soil properties and yield over time. These results demonstrate that soil health management practices can be effectively incorporated into viable potato cropping systems to improve soil and crop health as well as enhance long-term sustainability and productivity.
Accomplishments
1. Genetic diversity of pathogens causing blackleg and soft rot of potato. A major blackleg and soft rot outbreak, a severe and damaging potato disease caused by Dickeya and Pectobacterium spp., has resulted in substantial economic losses to potato production in the eastern half of the U.S. in recent years. In collaboration with the University of Maine and potato researchers from across the U.S., ARS scientists from Orono, Maine, determined the genetic diversity of the strains involved in the outbreak compared to other known strains from throughout the world. The vast majority of isolates associated with the recent disease outbreak were all of the same clonal genotype of D. dianthicola, but were uniquely different from other previously observed strains, suggesting a recently derived variant spread from a single source. Other genotypes and several Pectobacterium spp. also were associated and interacted with disease development and were distributed throughout the region, indicating complex interactions and multiple pathogens responsible for the outbreak. Improved detection and diagnostic tools were also developed to characterize these pathogens. These advances in understanding the pathogens involved in this disease complex can provide the basis for improved detection and control practices.
Review Publications
Ge, T., Johnson, S.B., Larkin, R.P., Hao, J. 2021. Interaction between Dickeya dianthicola and Pectobacterium parmentieri in potato infection under field conditions. Microorganisms. 9: 316. https://doi.org/10.3390/microorganisms9020316.
Ge, T., Jiang, H., Tan, E.H., Johnson, S.B., Larkin, R.P., Charkowski, A.O., Secor, G., Hao, J. 2021. Pangenomic analysis of Dickeya dianthicola strains reveals the outbreak of blackleg and soft rot of potatoes in USA. Plant Disease. https://doi.org/10.1094/PDIS-03-21-0587-RE.
Larkin, R.P., Honeycutt, C.W., Griffin, T.S., Olanya, O.M., He, Z., Halloran, J.M. 2021. Potato growth and yield characteristics under different cropping system management strategies in northeastern U.S. Agronomy Journal. https://doi.org/10.3390/agronomy11010165.
Ge, T., Jiang, H., Johnson, S.B., Larkin, R.P., Charkowski, A.O., Secor, G., Hao, J. 2020. Genotyping Dickeya dianthicola causing potato blackleg and soft rot associated with inoculum geography in Northeastern America. Plant Disease. https://doi.org/10.1094/pdis-10-20-2138-re.
