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

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.