Expansion of the European Race of <i>Gremmeniella abietina</i> in Newfoundland, Canada

Since its detection on ornamental pines in St. John's, Newfoundland, Canada, in 1979 (3), the European race causing Scleroderris canker (Gremmeniella abietina (Lagerb.) Morelet) has been detected throughout the Avalon Peninsula at the eastern end of the province. A quarantine was established on the Avalon Peninsula in 1980 to reduce the risk of introducing the disease to the natural red pine (Pinus resinosa Aiton) stands on the remainder of the island. Scots, red, and jack pines were examined at 34 locations in Newfoundland in 1998 and 1999. Infected trees were detected at four locations outside the quarantine zone. In the fall of 1998, the disease was found in plantations at three locations outside the quarantine zone: on Scots pine (P. sylvestris L.) at Bonavista and Catalina (≈135 km north-northeast of the quarantine) and on jack pine (P. banksiana Lamb.) and Scots pine at Sunnyside on Trinity Bay (≈45 km northwest of the quarantine). In 1999, the disease was detected at a fourth location on planted Scots pine in Come By Chance, near the Sunnyside location. Cultures of the pathogen were recovered from branch samples collected at each location and submitted for race determination at the Laurentian Forestry Centre, Sainte-Foy, QB. All isolates were determined based on the polymerase chain reaction diagnostic technique (1) to be the European race of G. abietina. This is a significant range extension from that reported by Laflamme et al. (2). The infected trees originated from the former Back River tree nursery at Salmonier Line that provided planting stock for a provincial reforestation program between 1937 and 1952. Evidence suggests that this nursery was the source of infected stock for plantations at nine locations within the Avalon Peninsula quarantine zone and the four new locations detected during the 1998 and 1999 surveys. This is similar to the pattern described for other nurseries in eastern Canada and the United States (2). The presence of the European race of G. abietina outside of the Avalon Peninsula increases the risk that the disease will become established in the rare natural red pine stands on the rest of the island of Newfoundland. References: (1) R. C. Hamelin et al. Appl. Environ. Microbiol. 59:1752, 1993. (2) G. Laflamme et al. For. Chron. 74:561, 1998. (3) P. Singh et al. Plant Dis. 64:1117, 1980.

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