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.

Bacterial Pathogen Submission Guidelines

Depending on the crop or the symptom area, there are specific sampling instructions. Please contact our Field Plant Pathologist for details, but below are some general guidelines:

• 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.
• 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.
• 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.
• Please include completed submission form(s) for each sample.
• Please contact the Perennia Plant Health Lab at planthealth@Perennia.ca to notify us of incoming samples

Drop off or Mail to:
Perennia Food & Agriculture
28 Aberdeen Street, Unit 6
Kentville, Nova Scotia B4N 2N1
877-710-5210

Figure 1: Fireblight (Erwinia amylovora) (bacterial) of apple sample submission with diseased and healthy stem and leaf tissue.

Figure 2: Plant sample cutting diagram. Position 1 indicates where a leaf tissue sample should be taken (try and include at least four leaves). Position 2 indicates where a stem tissue sample should be taken (make sure to include both healthy and diseased tissue). Position 3 indicates where a root tissue sample should be taken.