Performing Department
(N/A)
Non Technical Summary
The increasing demand for organic foods in the US is creating an opportunity for conventional vegetable growers to transition to organic production. However, pests and diseases are major barriers for transitioning growers since chemical pesticides are no longer options for pest management on transitioning and organic farms. Root-knot nematodes (RKN; Meloidogyne spp.) are among the critical yield-limiting pests of conventional and organic vegetable production in the US and around the world. When RKN populations reach damaging levels in fields, effective management approaches become imperative. However, as RKN continues to spread under the changing climate and emerging virulent RKN populations overcome host resistance, lack of effective methods for managing RKN post a significant barrier during transition to organic vegetable farming. This project focuses on research and extension activities to explore suppressive soils as a resource for growers to manage RKN in organic vegetable farming by (1) identifying suppressive soils against RKN at organic vegetable farms in Indiana and Kentucky and assessing the impacts of soil management practices on suppression via closely working with growers; (2) investigating microbial communities of representative suppressive soils to identify groups of microbes associated with RKN-suppressiveness. The microbes identified may serve as bioindicators of RKN suppressiveness of soils; (3) developing grower-friendly procedures to create RKN-suppressive soils by scaling up the identified suppressive soils or through de novo methods; (4) developing a new method for managing RKN in organic vegetable farming by transplantation with suppressive soils; (5) creating a knowledge-generating and sharing platform as a hub to guide growers for effective RKN management. With the collaborations between Purdue University, University of Kentucky, growers, conservation groups, organic industry, and other stakeholders, the multidisciplinary team aims to provide vital assistance to transitioning and organic vegetable growers with effective RKN management strategies and practices to facilitate smooth transition and successful organic vegetable production.
Animal Health Component
40%
Research Effort Categories
Basic
30%
Applied
40%
Developmental
30%
Goals / Objectives
The long-term goal of the project is to manage root-knot nematodes (RKN) by optimizing soil management in transitioning and organic vegetable farming. This project will conduct both research and extension activities to discover suppressive soils against RKN and explore suppressive soils as a resource for growers to manage RKN in organic vegetable production. Specific objectives include: 1. Exploring suppressive soils against RKN at organic vegetable farms and assessing the impacts of soil management practices on suppression; 2. Investigating microbial communities of suppressive soils to identify groups of microbes associated with RKN-suppressiveness; 3. Creating RKN-suppressive soils by scaling up the identified suppressive soils and through de novo methods; 4. Developing a new method for managing RKN in organic vegetable production by transplanting with suppressive soils; and 5. Creating a knowledge-generating and sharing platform among organic vegetable growers and the scientific community.
Project Methods
Objective 1: Exploring suppressive soils against RKN at organic vegetable farms and assessing the impacts of soil management practices on suppression. We aim to collect soil samples on ~ 100 organic and transitioning vegetable farms, including open fields and high tunnels, in Indiana and Kentucky, approximately 50 farms in each state to identify soils with natural suppression against RKN in Year 1. In Years 2 and 3, representative farms with suppressive soils identified in Year 1 will be followed up to monitor the changes in soil suppression efficacy against RKN. The presence of RKN species and population density will also be checked and documented for each soil sample collected. We will collect and analyze soil properties and farm management information. We aim to identify soil properties and/or management practices that are significantly correlated with soil suppressiveness to RKN. The plant-parasitic nematode report and results of soil suppressiveness against RKN will be shared to each participating grower. Objective 2: We aim to identify core groups of microbes associated with RKN suppressive soils. These core microbe groups will be used as indicators of soil suppressiveness on RKN during this project. We will select 18 representative suppressive soils identified in Obj. 1 based on efficacy on RKN suppression, soil texture, and years the soils have been in organic management. Similar criteria except for RKN suppressiveness will be used to select 6 conducive soils as controls for microbiome analysis. For each soil or nematode sample, DNA will be extracted and 16S and ITS-amplicon metagenomic sequencing will be carried out o to study bacterial and fungal communities, respectively. Alpha and Beta diversity analyses, and comparative analyses, including differential abundance and core microbiome analysis to identify the groups of bacteria and/or fungi that are specifically present or highly associated with the suppressive soil samples. We will study the dynamic changes of microbiome in suppressive soils in Year-2 and 3 to confirm the association of core microbes identified with RKN suppressiveness. Objective 3: We propose to create RKN-suppressive soils by scaling up the identified suppressive soils (Obj. 3.1) and through de novo methods (Obj. 3.2). Obj. 3.1: based on the preliminary data, our hypothesis is that by mixing identified suppressive soils from organic farms with the widely available conducive soils on organic farms and nurturing the microbial growth in the mix, the mixed soil can develop suppressiveness and increase in volumes of suppressive soils. We will test the effects of factors, including soil mix ratio, moisture, temperature, incubation timing and organic matter amendments, on scale-up of RKN suppressive soils. Obj. 3.2: We aim to learn from organic vegetable growers who have successfully built suppressive soils against RKN and translate their knowledge to optimized protocols, which will help more transitioning and organic growers to manage RKN. We will learn from farmers and apply results generated from Obj. 1 to develop 2-3 protocols representing typical organic vegetable farming scenarios (open-field vegetable production, monoculture high tunnel tomato production and four-season high tunnel production, etc.). We will follow the protocols and test the effectiveness of converting conductive soils to suppressive soils. The experiment will be conducted at Purdue SWPAC organic field, organic or transitional vegetable farms with RKN-conductive soils in Indiana. The two procedures, scaling-up and de no creation, will provide transitioning and organic vegetable growers ways to develop suppressive soils to manage RKN and potentially other plant-parasitic nematodes on their farms. Objective 4: We propose to develop and validate a new method for managing RKN in organic vegetable production by transplanting with suppressive soils. The vertical distributions of RKN in soil were mainly found in the top 30-cm soils in fields during growing seasons. Our hypothesis is that providing a protective zone to vegetable plant roots in this depth by transplanting with suppressive soils can reduce RKN infection of roots and therefore yield losses. In addition, plant roots grown laterally out of the protective zones may be protected by the beneficial rhizomicrobes originally in the suppressive soils which can propagate along developing roots to the outside of the suppressive soil zone. We will test the hypotheses by conducting experiments in greenhouse at Purdue University to optimize the transplanting method and further conducting on-farm trials in Kentucky to validate the efficacies of the methods on reducing RKN infection and alleviating yield losses. We expect that the optimized vegetable seedling transplanting with suppressive soil can provide effective protection of vegetable plants from RKN infections. Objective 5: Creating a knowledge-generating and sharing platform among organic vegetable growers and the scientific community. This project aims to enhance the understanding and utilization of natural suppressive soils in the management of RKN. Organic vegetable growers play pivotal roles in advancing this knowledge and will be encouraged to join the Extension members of the team to facilitate the dissemination of project findings to a broader audience. The project outcomes will be communicated to the broader farming community through various Extension platforms, including field days, presentations at farmers' conferences, articles in Extension newsletters and popular media. Additionally, we will produce videos and audio content and contribute to both existing and newly developed farmers' webinars and podcasts. The Purdue Nematology Lab website (https://ag.purdue.edu/department/btny/labs/zhang/index.html) will serve as the central information hub for this project, providing timely updates on project activities and disseminating new findings.Evaluation Plan: Research performance of the project will be evaluated by publishing research findings as peer-reviewed journal articles, extension publications and informative articles on websites. The number of times that the information is accessed or downloaded, and citations of journal articles will be monitored. For Obj.1, we will monitor the number of growers interacted and soil samples collected, and suppressive soils against RKN identified during the project. Obj. 2, we will monitor the number of suppressive soils included in the soil microbiome analysis, and the diversity and core microbes identified in representative suppressive soils. Obj. 3, the success rates of creating suppressive soils by scale-up and de novo methods will be closely monitored, and optimizations will be made when necessary. Obj. 4, efficacies of RKN management by vegetable transplanting with suppressive soils will be monitored. We will actively involve growers and stakeholders in the four research objectives to build connections which are important for the extension activities we will conduct.