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Sampling and Testing for X-disease and Little Cherry Disease

If you have trees with small, misshapen or poor colored fruit and suspect Little Cherry or X-disease, sample if the disease has not been previously confirmed in the block. For a tutorial on sampling for X-disease and Little Cherry Disease see Scouting and Sampling for Little Cherry Disease.

Material to sample

Submit four five-inch cuttings from the diseased limb(s) including young woody tissue (pencil size previous season wood), leaves and fruit stems.

New information!

  • Woody material should be from the previous season or older because we have found that current season growth can have variable pathogen concentrations.
  • New research shows that leaves may test negative even though the wood they’re attached to is positive, therefore leaves by themselves are not recommended.
  • Pencil sized wood from the previous season and fruit stems are the best tissue to sample.

Note: The information is based on current on-going research.

hands holding small branches with cherries on them

Where to sample:

Trees with symptoms: Sample from symptomatic limbs.

Trees with no symptoms: Sample from each leader.

When to sample:

The week before harvest to mid-August.

Sample condition:

Keep tissue moist and cool (e.g. package with a cold pack). Old or dried tissue is more likely to have false negatives.

Where to send samples:

See labs page

Download sampling fliers:

Scouting flier vf (2021.02.04)   Muestreo de X Fitoplasma y Little Cherry Virus flier WSU OSU (2021.02.04) [pdf]

Recursos en Español

Additional information

X-disease webpage

Little Cherry Virus webpage

Symptoms Gallery

X-disease Vector Gallery

Nursery Prevention of X-disease Phytoplasma and Little Cherry Virus Recommendations

BMPs for tree removal for X-disease and Little Cherry Virus infected trees

Case studies on tree removal for X-disease phytoplasma and Little cherry virus

Alternative weedy hosts for X-disease phytoplasma.


Symptoms of Little Cherry Virus and X-disease Phytoplasma.

Síntomas de Fitoplasma X y Little Cherry Virus.

Symptoms of X-disease Phytoplasma in Stone Fruit.

Síntomas de Fitoplasma X en Frutas de Hueso.


Corina Serban professional photo
Corina Serban
WSU Extension
(509) 574-1595
Tianna DuPont
Tianna DuPont
WSU Extension
(509) 293-8758
Bernardita Sallato professional photo
Bernardita Sallato
WSU Extension
(509) 439-8542
Scott Harper professional photo
Scott Harper
Department of Plant Pathology, Washington State University
(509) 786-9230
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Tobin Northfield
WSU Entomology
(509) 293-8789



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