Phytophthora lateralis detected again in the Netherlands
In 2005, Phytophthora lateralis (EPPO A1 List) was found for the first time in the Netherlands in the province Drenthe on Chamaecyparis lawsoniana. All C. lawsoniana plants in the nursery concerned were destroyed. Subsequent annual surveys on P. lateralis were focussed on this nursery and its vicinity and confirmed the absence of the disease. However, in 2010 P. lateralis was detected again on C. lawsoniana in a nursery located in Almedo (province of Overrijssel). No link could be established between these two findings (the two nurseries are 85 km apart).
In Almedo, the infected plants were found in a plot of 400 m² in which approximately 2000 Chamaecyparis plants were grown. During a field inspection, some plants showing brown discoloration at the stem base and general decline were noticed. The pathogen was isolated on agar medium and PCR testing confirmed the presence of P. lateralis. The possible sources of this infection have been investigated but could not be determined. Imports of Chamaecyparis lawsoniana from outside Europe are prohibited, and there was no evidence that planting material originally produced by another Dutch nursery was the source of infection. Although it could not be excluded that infected soil adjacent to roots of non-host plants might have been a pathway, nothing could confirm this hypothesis.
The infected area (approximately 100 m²) was delimited by collecting and testing additional plant samples. All plants in the infected area, as well as those located within a buffer zone of 2 m radius will be destroyed. Movements of the remaining Chamaecyparis plants will not be allowed until 2011-09-31 (and only after confirmation of the absence of P. lateralis). Precautions will also be taken to avoid the dissemination of spores by human activities (e.g. by cleaning of machinery, equipment and shoes). Annual surveys on P. lateralis will continue in the Netherlands.
The pest status of Phytophthora lateralis in the Netherlands is officially declared as: Transient, under eradication.
Sources
NPPO of the Netherlands (2010-11).