Phytophthora Species
Phytophthora species are the most destructive group of plant pathogens world wide, with Phytophthora cinnamomi having the greatest known impact on native forests and bushland ecosystems in many of the temperate regions of the world.
P. cinnamomi is the primary cause of the disease most commonly recognised as Phytophthora Dieback in native plant systems throughout southern Australia and is the most prominent concern for land managers. P. cinnamomi is a soil borne pathogen infecting the roots and collar of susceptible plant species. It can be detected directly from the soil, infected roots and lesion front at the collar of infected plants.
However, there are many species of Phytophthora, with several other species also being associated with tree declines. Depending on the sample and plant system, it may be important to identify an alternate species of Phytophthora depending on the location, host and probable pathogen species involved.
Sample Analysis
Isolation and Identification of Phytophthora Species
The process of isolating and detecting Phytophthora species from soil and plant material is quite involved and generally takes between 1 and 4 weeks to produce a definitive result depending on the level of information required and the species being isolated.
During our routine diagnostic analysis we isolate Phytophthora cultures whereby they are identified in the first instance based on morphological characteristics under a microscope. Due to the presence of characteristic collaroid hyphae, P. cinnamomi isolates are usually identified based on these primary isolations.
Once identified as a Phytophthora isolate, some species are easier to differentiate microscopically than others due to characteristic structures that are readily induced and observed in culture. However, where these are not present, PCR and DNA sequence analysis provide the fastest means of identifying individual isolates.
Our Approach:
- CPSM Diagnostics will analyse all samples submitted using the most appropriate culture-based isolation techniques for the sample, which may involve soil baiting and/or direct plating onto selective agar.
(6-14 days)* - Isolates with hyphal characteristics consistent with Phytophthora species are sub-cultured onto individual culture-plates, incubated and assessed microscopically.
- The identity of P. cinnamomi can generally be confirmed based on these sub-cultures. All other Phytophthora isolates are identified to genera level based on these sub-cultures.
(2-7 days)* - Where required by the client, isolates can be identified to species level based on DNA sequence analysis for an additional fee.
(7-10 days)*
* Analysis times may vary depending on the time taken for isolates to grow in culture with some species of Phytophthora taking considerably longer than others.
