Assessing risk of False Blossom Disease and vector introduction and establishment to Washington and Oregon Cranberry Producing Regions

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Commodities

• Fruits: berries (cranberries)

Practices

• Pest Management: disease vectors, field monitoring/scouting, prevention

Preventing the introduction and establishment of an invasive species is more cost-efficient and environmentally sustainable than attempts to manage it later. The phytoplasma called False Blossom Disease threatens cranberries on the East Coast and in Wisconsin. This disease results in stunted flowering that causes permanent yield loss in these perennial plants, which must then be removed. False Blossom Disease (FBD) can be spread either through nursery cuttings, like those used to replant or ‘renovate’ a cranberry bog, or via an insect vector, the Blunt Nose Leafhopper. Currently, there are no recorded cases of FBD on the West Coast (United States and Canada) but it is uncertain if the insect vector already exists here.

We propose an intensive sampling program of the major cranberry growing regions in Washington and Oregon to scout for the vector. If found, or if bogs contain symptoms of FBD, then we will use a nested PCR design to test for FBD.

During sampling, we will work with growers in Washington and Oregon to educate them on the disease and its identification as well as to provide growers with guidance on how to prevent this disease-pest system from spreading to the West Coast, by attempting to change renovation practices whereby growers purchase untested vines from Wisconsin and New Jersey. To evaluate our program, we have designed a pre- and post-test on knowledge of false blossom disease, a pre-/post-survey and a pre-/post-focus group on behaviors and attitudes towards renovation practices and prevention of spread of this disease.

Research Objective 1. Characterize and determine relative abundance of leafhoppers, including the blunt-nose leafhopper, in Washington and Oregon cranberry growing regions. For each bog sampled, we will measure leafhoppers from samples to genus noting diversity and abundance. Samples can be kept in 70% ethanol almost indefinitely which will allow us to quantify samples in winter once field work has been completed. Samples will be taken and quantified during 2024 and 2025.

Research Objective 2. Determine if false blossom disease is present in cranberry bogs that have the blunt-nose leafhopper and/or vines with symptoms similar to false blossom with molecular diagnostic assays.  All bogs with BNLH present or with symptoms will be tested for presence/absence of FBD phytoplasma using a nested PCR diagnostic test by the USDA team that has experience with plant pathology testing. Any necessary sampling and testing will be done in field seasons 2024-2026 depending on when BNLH or FBD symptoms are found.

Educational Objective 1. Improve grower knowledge of False Blossom Disease, its symptoms, its potential economic effects to the region, and where it is currently found (including updated research from the survey of West Coast bogs). We will use a pre/post-test, which Kraft frequently uses to assess knowledge gain to capture this output. The pre-test will be handed out in 2024 at the start of the project while the post-test will be taken in winter 2025-2026 at the culmination of the project.

Educational Objective 2. Design a survey tool and host informal focus groups in each region during their regular annual meetings to discuss the threat of FBD and determine behavior and attitudes at the start and end of the program. The survey will specifically focus on questions regarding behavior and attitudes as written in collaboration with a social scientist on another project and will capture measurable change in behaviors and attitudes when used twice as a pre/post-survey. We will give growers the survey in winter 2023-2024 before this project would start and again in spring/summer 2026 when the project wraps up.