Project Overview
Annual Reports
Commodities
- Vegetables: carrots
Practices
- Crop Production: application rate management, cover crops
- Education and Training: extension, on-farm/ranch research
- Pest Management: cultural control, disease vectors, field monitoring/scouting, integrated pest management, precision herbicide use, weed ecology
Proposal abstract:
Wisconsin carrot fields are threatened annually by the aster leafhopper, which has emerged as the dominant insect pest due to its ability to transmit the aster yellows phytoplasma (AYp). Currently, disease control is achieved through insecticidal sprays that target populations of the aster leafhopper within the susceptible crop. A more comprehensive and sustainable management approach to limit AYp will require a diversified control strategy. AYp persists in the landscape in alternate host plants that may act as the primary inoculum sources where leafhoppers acquire and subsequently spread AYp within and among carrot fields. An improved knowledge of where leafhoppers acquire the pathogen, when they move into susceptible fields, and when they spread the pathogen to crops is critical to understanding and managing the spread of AYp. The outlined research will generate new information about the identity and importance of primary inoculum sources and their role in the spread of disease throughout carrot fields. Specifically, we propose to: 1) accurately identify natural sources of AYp in habitats surrounding carrot fields, and 2) evaluate AYp genetic variability in the carrot agroecosystem to determine if AYp variability relates to to either disease prevalence or infectivity of the pathogen. The results will be used to assess local AYp risk based on the habitat immediately surrounding a carrot field in terms of inoculum potential, virulence and insect phenology. Outcomes from this project will inform growers about the primary sources of AYp in off-crop habitats and will propose methods to determine AYp risk in selected fields. The information produced by this research will improve growers’ abilities to manage off-crop habitat in ways that decrease the accumulation of AYp inoculum the local environment, which will contribute to long-term, sustainable carrot production through reductions in insecticide inputs.
Project objectives from proposal:
This project has two main objectives:
Objective 1: Accurately identify of the primary reservoir hosts of AYp in habitats surrounding carrot fields and determine which have the greatest epidemiological importance as potential inoculum sources.
Objective 2:
I) Compare the genetic structure of the population of AYp isolates collected from reservoir hosts and within affected carrot, and
II) determine if AYp variability relates to either disease prevalence or infectivity (virulence) of the pathogen.
In the short-term, this project will provide data about factors that relate to the distribution and spread of AYp, such as inoculum reservoirs, pathogen variability and leafhopper phenology, in the carrot agroecosytem.
The intermediate-term goals will be to assess local AYp risk based on the habitat immediately surrounding a carrot field. Information on the progress and results of our field trials will be disseminated directly to interested farmers, and through local and regional conferences including the University of Wisconsin, Cooperative Extension and the Wisconsin Potato and Vegetable Growers Association’s (WPVGA) annual Grower Education Conference. We also plan to publish the results of our field trials in a journal dealing with research into sustainable agricultural systems.
In the long-term, the knowledge gained from this project will improve growers’ abilities to manage off-crop habitat in ways that minimize the persistence and decrease the accumulation of AYp inoculum in the local environment. The incorporation of habitat management as an additional control tactic will contribute to the sustainability of carrot production primarily through reductions in pesticide use.