Phytophthora ramorum - Molecular diagnosis (PCR)
Phytophthora ramorum is a species of plant fungal pathogen Phytophthora genus, order Pythiales, family Pythiaceae, which causes the so - called sudden oak death (SOD). This disease mainly affects oak and other tree species, but can also affect other plant species such as Rhododendron, Viburnum and Pieris, causing leaf symptoms known as ramorum dieback or ramorum blight. This pathogen is especially located in North America, but has also been identified in European countries.
The transmission of this pathogen can occur through zoospores, sporangia and chlamydospores. Furthermore, it can be transmitted by insect vectors act as, infected plants, soil or water from splashing rain and irrigation. On the other hand, the movement of ornamental plants, firewood, and the activity of people can contribute to their spread. Some beetles are found in diseased trees could play a role as potential vectors, however, this aspect is not yet clear.
From a morphological point of view, it is characterized by Phytophthora ramorum produce abundant culture medium chlamydospores of 22-80 microns in diameter, primarily terminals, the hyaline principle that eventually changed to pale brown. The sporangia are also produced abundantly in culture medium and are elongated, with an average length of 40-80 x 20-32 microns, or sometimes pointed rounded base, with simple and narrow papilla.
In infected trees, the first symptoms associated with this disease include wilting of new buds and pale green color of the leaves. After a period of about 2 to 3 weeks, the foliage turns brown, fluid losses are presented in the lower trunk of the tree and vine death. Also, the crust can cracking and oozing resin with a visible discoloration. Then the tree can be attacked by beetles and fungi, causing the death of one year after the initial infection tree and several months after it has been infected by beetles.
The impacts associated with Phytophthora ramorum in forest ecology involve the loss of diversity of plant species and wildlife population changes due to the colonization of new species of plants and trees, changes in the structural characteristics of forests and high mortality in the community of native pollinators due to the residual effects of heavy spraying pesticides to treat symptoms associated with infection by Phytophthora ramorum. In addition, as a result of tree mortality may arise other environmental problems such as an increased risk of fire.
Recommended tests for diagnosis:
The diagnosis is based on molecular diagnostic methods (PCR).
Tests in IVAMI:
- Molecular diagnosis (PCR), to detect DNA of Phytophthora ramorum.
- It infected plant tissue.
Preservation and shipment of sample:
- Refrigerated (preferred) for less than 2 days.
- Frozen: over 2 days.
- Molecular diagnosis (PCR): 24 to 48 hours.
Cost of the test: