Viruses

Plant viruses are obligate parasites that infect host plants and use their cellular machinery to replicate and proliferate. They can gain entry into a plant in many different ways, including vectors (i.e., nematodes, aphids, whiteflies), vegetative propagation and wounding. The symptoms associated with virus infection can vary greatly and can be confused with other common abiotic and biotic stressors. They can affect many different marketable parts of plants (i.e., leaves, flowers, fruit and stems), resulting in reduced yield and quality. Once a plant is infected with a virus, it is infected for life, and depending on how the virus is transmitted, it can spread to neighbouring healthy plants in a field or greenhouse.

Diagnosis of viruses by eye is very challenging due to their variation in symptoms. A laboratory test is the most reliable form of diagnosis, such as an enzyme-linked immunosorbent assay (ELISA) or a polymerase chain reaction (PCR) test. The Plant Health Lab currently offers PCR testing for grapevine, raspberry and strawberry viruses

Plant Virus Submission Guidelines

Depending on the crop, there are specific sampling instructions. Please reference the Plant Health Lab website or contact our molecular biologist at planthealthlab@perennia.ca for details.

Found below are some general guidelines for submitting samples.

• Collect mature leaves that are free of disease, insects and mechanical damage. Leaves should not be senescing or dropping. Leaves should be dry.
• Individual plants can be tested, or leaves can be pooled from a field. For an individual plant, it is recommended that four leaves be sampled from different portions of the plant, and the plant be flagged in the field. If pooling samples, multiple pooled samples from a field should be taken in a systematic pattern to get an idea of virus pressure across the whole field.
• Leaves should be submitted with petioles (leaf stem) intact. This can be achieved by slowly bending the petiole back until it is released from the stem. Avoid touching the ends of petioles to avoid cross-contamination.
• See Fungal/Bacterial Submission Guidelines above for shipping instructions.
• Do not add moisture to the bag, and do not freeze samples.
• If storing/shipping with ice/ice pack, put an insulative barrier (such as a piece of cardboard) between the samples and the ice/ice pack to prevent direct contact. Otherwise, samples can freeze, especially grape tissue.
• Grapevine Virus Sampling Video (opens in a new tab)