Apple Proliferation Phytoplasma No Longer Suspected in Canadian Apple Orchards

Apple Proliferation Phytoplasma No Longer Suspected in Canadian Apple Orchards

WASHINGTON, October 23, 2013—In early April, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service announced that the Canadian Food Inspection Agency (CFIA) had detected apple proliferation phytoplasma (APP) in a Nova Scotia apple orchard—marking the first APP detection in North America. Four orchards were placed under quarantine. Between May and October 2013, CFIA surveyed the orchards for symptoms of APP and samples were collected and tested. No symptoms of APP were found and the laboratory test results were negative for APP and other phytoplasmas. All four orchards are being released from quarantine. The trees that demonstrated the suspect symptoms were all ‘Pacific Gala’ and were exported to Canada from a certified U.S. nursery in 2008. The nursery that exported the trees, as well as the nursery that developed the rootstock, were also tested extensively and all tests were negative for APP. CFIA never imposed any restrictions on the importation of apple trees from the United States.

APP, or ‘Ca. P. mali’, is considered to be a quarantine pest in both Canada and the United States. It is present throughout Europe, where it is considered to be one of the most critical diseases of apple trees.  Symptoms of APP include:

• shoots around axillary buds, which create a broom-like appearance at the end of affected branches
• leaf rosetting
• enlarged leaf stipules
• reduced growth and smaller, less sweet fruit