The USDA Animal and Plant Health Inspection Service (APHIS) has been notified by the Canadian Food Inspection Agency (CFIA) that they have detected apple proliferation phytoplasma (APP) in an apple orchard near Kentville, Nova Scotia. The affected orchard has been placed under quarantine. This is the first APP detection in North America.
The affected trees are Pacific Gala and were imported into Canada from the U.S. in 2008. It is important to note that no symptoms of APP have been observed in the source nurseries or reported in the U.S. at large, and the source of infestation is unknown at this time. APHIS has provided trace forward information to CFIA, and is currently conducting testing at the source nurseries. At this time, CFIA has not imposed new restrictions on importation of apple trees from the U.S.
APP, or ‘Ca. P. mali‘, is considered to be a quarantine pest in both Canada and the U.S. It is present throughout Europe, where it is considered to be one of the most critical diseases of apple trees. APP is spread through propagation practices with infected material including budding and grafting. Long-distance dispersal of APP occurs through the trade of infected rootstock, scionwood, or budwood. Specific insects, including certain psyllids, froghoppers, and leafhoppers, also spread APP, however it is not transmitted through seed or fruit or pruning.
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.
For more information on APP, contact Craig Southwick at Craig.Southwick@aphis.usda.gov or 970-494-7578.