Plant Health Lab Services

Plant diseases are caused by a diversity of pathogens such as fungi, bacteria, viruses, and nematodes and these pathogens pose a serious threat to sustainable agricultural production systems. Efficient and early diagnosis of disease-causing pathogens is essential for implementation of control strategies to mitigate negative economic impacts. Perennia’s Plant Health Lab was created in 2018 to help local producers through classical and molecular approaches for early disease diagnostics. Perennia’s team of commodity specialists supports our lab and together we provide growers with a holistic approach to managing pathogens. The lab is constantly expanding, so please contact our pathologist and molecular biologist to learn more about our offerings. If you have general questions and comments, please contact us below.

Samples can be dropped off at our Kentville office (28 Aberdeen Street) between the hours of 8:00 – 4:30.
Please review the sample submission guidelines and fill out a sample submission form. If you have any questions, please contact one of our staff.

Our Team

Molecular Biologist

Dr. Kendra McClure

Kendra completed an M.Sc. in horticulture and a Ph.D. in plant breeding and genetics at the University of Guelph. She has worked in the field of agricultural research and extension for over a decade, and runs the Plant Health Lab’s molecular lab.

Contact our Molecular Biologist

Plant Pathologist

Dr. Sajid Rehman

Sajid Rehman completed his M.Sc. and Ph.D. in plant pathology from Wageningen University, The Netherlands. He has more than 10 years of research experience working with different plant pathogens (Fungi, nematodes, bacteria) of diverse crops.

Contact our Pathologist

Plant Disease Diagnostics

Fungi

Fungi and fungi-like organisms inflict huge yield losses globally despite the abundant use of fungicides. Plant pathogenic fungi cause disease symptoms on all plant parts (seed, seedling, leaves, fruits, and root). Symptoms may include spots and blights on leaves, stems, and fruit, rots of tubers, cankers, damping off, seedling and plant diebacks, galls, and wilts. Their early detection in infected plant tissue will ensure taking preventative measures.

Fungal disease diagnosis at the Plant Health lab consists of classical approaches based on visual disease symptoms, hyphal and spore morphology, shape and size of conidia and other fruiting structures. Fungal infections are often systemic, and plant tissue is surface sterilized followed by incubation either on sterile filter paper under humid conditions or incubated on selective media for their successful isolation and identification. In some cases, molecular methods such as PCR and DNA sequencing are used to resolve the causal species.

  • Briefly describe the problem/symptoms on the sample submission form.
  • Sample must be representative of the symptoms observed in the field.
  • Select samples that are still alive with visible symptoms. Dead or dying tissue should not be sampled.
  • Plants should be dug (not pulled) so the entire root system remains intact.
  • Be sure to collect the sample prior to pesticide application. Pesticides may interfere with diagnosis.
  • Wrap the plant/plant parts in a paper towel and enclose it in a plastic bag so that the sample does not dry out. Be sure to shake off any excess soil from the roots or send them in a separate plastic bag.
  • Specimen must be fresh. If a sample cannot be mailed immediately, keep it refrigerated or in a cool area out of sunlight.
  • Pack the sample securely in the Styrofoam/cardboard box and mail it or drop off.
  • If possible, choose the fastest method to mail out the sample. Mail early in the week to avoid weekend delays.
  • If dropping the sample off in-person, please include completed submission form with the sample, notify Dr. Sajid Rehman of intended drop-off time.
  • Shipping samples immediately after sampling is the best option. Otherwise, samples can be stored briefly at 4-10°C until they can be shipped. DO NOT freeze samples or expose them to heat.

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 and strawberry viruses.

Depending on the crop, there are specific sampling instructions. Please contact our molecular biologist for details, but below are some general guidelines:

  1. Collect mature leaves that are free of disease, insects and mechanical damage. Leaves should not be senescing or dropping. Leaves should be dry.
  2. 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.
  3. 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.
  4. Place your samples in labelled resealable plastic bags and keep them cool (out of direct sunlight, in a fridge) until shipped or dropped off at the Plant Health Lab. Samples shouldn’t be refrigerated for more than one night before shipment or delivery. Do not add moisture to the bag, and do not freeze samples.
  5. Label your bags with a unique sample ID written in permanent marker that you can trace back to the sampled plant.
  6. Send samples in a Styrofoam cooler with ice packs. Place a piece of cardboard between the ice pack and the bags of leaves so the leaves do not freeze.
  7. If delivering samples in person, let the Plant Health Lab know in advance when they’ll be dropped off. The Perennia Truro offices do not accept Plant Health Lab samples.
  8. Always include a sample submission form, and read the Plant Health Lab disclaimer statement.
  9. Perennia staff can visit your farm and collect samples on your behalf for an additional fee. This should be arranged at least one week in advance.

Bacteria

The diseases caused by bacteria in horticultural crops impose varying degrees of economic impacts. Many genera of bacteria, Agrobacterium (galls on plants), Ralstonia (wilts), Pseudomonas, Xanthomonas or Pantoea (leaf spot, blight, blast, cankers and wilt), Corynebacterium or Curtobacterium (leaf spot, fruit spot and wilt) and Erwinia or Dickeya (soft rot or wilt) are known plant pathogenic bacteria.

At the Plant Health Lab, our plant pathologists use visual disease symptoms, bacterial streaming, culturing on selective media and DNA sequencing to identify the causal bacterial species.

  • Briefly describe the problem/symptoms on the sample submission form.
  • Sample must be representative of the symptoms observed in the field.
  • Select samples that are still alive with visible symptoms. Dead or dying tissue should not be sampled.
  • Plants should be dug (not pulled) so the entire root system remains intact.
  • Be sure to collect the sample prior to pesticide application. Pesticides may interfere with diagnosis.
  • Wrap the plant/plant parts in a paper towel and enclose it in a plastic bag so that the sample does not dry out. Be sure to shake off any excess soil from the roots or send them in a separate plastic bag.
  • Specimen must be fresh. If a sample cannot be mailed immediately, keep it refrigerated or in a cool area out of sunlight.
  • Pack the sample securely in the Styrofoam/cardboard box and mail it or drop off.
  • If possible, choose the fastest method to mail out the sample. Mail early in the week to avoid weekend delays.
  • If dropping the sample off in-person, please include completed submission form with the sample, notify Dr. Sajid Rehman of intended drop-off time.
  • Shipping samples immediately after sampling is the best option. Otherwise, samples can be stored briefly at 4-10°C until they can be shipped. DO NOT freeze samples or expose them to heat.

Nematodes

Plant parasitic nematodes are soil-inhabiting microscopic worms with a body length of less than 1 mm. They are ubiquitous, found in all climates and every type of soil. Plant parasitic nematodes rank amongst the most difficult pests to diagnose, identify and control due to their presence in soil. Some of the aerial symptoms associated with nematode feeding of roots are chlorosis (yellowing) of foliage, patchy/stunted growth, wilting, leaf rolling and die-back of perennial or woody plants. Below-ground symptoms on the roots may include galling, shortened, stubby or abbreviated roots, excessive root branching, root lesions, tuber necrosis, tuber cracking, forking of carrots, cysts or ‘pearly’ root and altered root architecture.

Proper identification of nematode species diversity and population density are important aspects for their effective management. Perennia’s Plant Health Lab offers soil analysis to determine plant parasitic nematode population density and species diversity. The classical approaches resolve nematode identification to the genus level, but DNA barcoding provides resolution to the species level.

  1. Nematode populations are not evenly distributed in the field, and the number of soil samples from an area will determine the precise estimate of its population diversity and density. It is very important to follow a consistent sampling style and pattern (Figures 1 and 2).
  2. About 20-cores per acre (30 cores per hectare) with the soil probe/auger/gardening tool at a soil depth of 10-20 cm should be collected in a plastic bucket. It is estimated that about 1-2 kg of composite soil samples will be collected and submitted to the lab for estimating nematode population density.
  3. Care should be taken not to take soil samples from too wet and/or dry soil.
  4. Depending on the crop, 25-100 g of composite root sample is sufficient to determine the nematode population density in the roots. The root sample should always accompany soil; otherwise, nematode can desiccate and die.
  5. Nematodes are quite sensitive to environmental conditions. The soil sample should be put into a plastic bag, stored under shade or in an insulated container. A soil sample can be stored for a maximum period of two weeks in a refrigerator.
  6. In the case of annual crops, a soil sample should be taken just before or after harvest. But in the case of perennials, a soil sample should be taken during the growing season when the plant is actively growing. The nematode population tends to drop during fall and early spring.

Figure 1 and 2. Different soil sampling patterns.

Samples can be dropped off at our Kentville office (28 Aberdeen Street) between the hours of 8:00 – 4:30.
Please review the sample submission guidelines and fill out a sample submission form. If you have any questions, please contact one of our staff.

Contact Perennia’s Plant Health Lab

DISCLAIMER AND RELEASE OF LIABILITY

Please be advised that where a sample, provided by the Client, has tested negative for the presence of a virus or a pathogen that this negative test does not prove unequivocally the absence of virus or pathogen. This potential for a False Negative Test is due to seasonal and temporal fluctuation in pathogen levels, the inherent limitations of sampling and testing protocols, and the possibility of pathogen strain variability.  Therefore, Perennia makes no representations or warranties to the Client, that a negative test result from a sample is unequivocally free of infection, and subsequently Perennia shall not be liable for any loss or damage suffered by the Client due to any resulting management decisions the Client makes based on the negative test results. The Client agrees that any and all claims for loss or damage which the Client has or in the future may have against Perennia arising out of or related to the provision of Services, whether such claim is founded in contract or tort, shall be strictly limited to the amount of fees actually paid by the Client to Perennia for the Services. This disclaimer and release of liability shall also be binding upon the Client’s successors, heirs, executors, and administrators.

USE OF INFORMATION

By submitting a sample to Perennia, the Client agrees to the use of the Client’s test results for research purposes only in an anonymous aggregate form. Perennia treats all information collected by the Perennia as confidential subject to meeting the requirements under the law.