Phytophthora ramorum in Norway
In Norway, Phytophthora ramorum (EPPO Alert List) was isolated in November 2002 from Rhododendron catawbiense with wilting branches in a nursery in Bergen. After this first detection, an official survey was carried out in 2003 on various ornamental plants. Out of 21 samples collected from 10 locations, 2 samples were found infected by P.;ramorum. These infected samples had been taken from imported rhododendron plants (see EPPO RS 2003/133). In 2004, 133 samples from 53 locations were tested and P. ramorum was found in 29 locations. It was detected in 57 samples of rhododendron, 1 of Pieris japonica and 1 of Kalmia. In 2005, at the beginning of the year, 142 samples were tested (including plants from 45 import shipments) and 19 were found positive (including 6 from 5 imported lots). In addition, 370 samples from 74 nurseries and garden centres were analysed and 97 samples from 43 locations were found positive (all corresponded to rhododendron plants). 10 of these 43 locations had already been found positive in 2004. In 2005, P. ramorum was also detected on well established Viburnum fragans and rhododendron shrubs in a private garden in Bergen, as well as on rhododendrons in 4 public gardens in Bergen and 2 in Stavanger. It is noted that the production of rhododendrons in Norwegian nurseries is limited and that most of the plants are imported (from March to May) from other European countries. It is therefore difficult to determine if these repeated findings are resulting from re-introductions or from eradication failures from one year to another.
The situation of Phytophthora ramorum in Norway can be described as follows: Present, found in nurseries mainly on rhododendrons, isolated findings in gardens, under eradication.
Sources
Herrero ML, Toppe B, Klemsdal SS, Stensvand A (2006) First report of Phytophthora ramorum in ornamental plants in Norway. Plant Disease 90(11), p 1458.