Apple Proliferation Phytoplasma (APP): Questions and Answers

What is apple proliferation phytoplasma?

APP (Candidatus Phytoplasma mali ['Ca. P. mali']) is a bacteria-like plant pest of apple trees that affects fruit quality and the overall viability of a tree. This pest is considered to be a quarantine pest by Canada and the United States (U.S).

Has apple proliferation phytoplasma been detected in Canada?

APP has been detected by the Canadian Food Inspection Agency (CFIA) in an apple orchard near Kentville, Nova Scotia. This is the first detection of APP in North America.

How is the CFIA planning to respond to detections of this disease in Canada?

The CFIA has put the affected orchard under quarantine. The CFIA is gathering and analysing information related to this disease and its detection in Canada in order to determine the appropriate regulatory response.

What are the symptoms of apple proliferation phytoplasma?

Symptoms include a broom-like appearance of branches, the development of abnormal leaf clusters (leaf rosetting), and reduced fruit size and sweetness. APP decreases overall tree growth and viability.

What are the host species of apple proliferation phytoplasma?

The main host of APP is apple trees. In Europe, APP has been reported in other economically important species such as oaks, hazelnuts, hawthorns, plums, magnolias, dahlias, roses, and European and Asian pears. The impact of the disease on these secondary hosts remains unclear.

How is apple proliferation phytoplasma spread?

APP is spread through propagation practices such as budding or grafting with infected material. Therefore, long-distance dispersal of APP occurs through the trade and use of infected rootstock, scionwood, or budwood. It is also spread by specific insects, including certain psyllids, froghoppers and by leafhoppers. APP is not transmitted through seed, fruit, or pruning.

Do the insects known to spread apple proliferation phytoplasma occur in Canada?

The froghopper Philaenus spumarius and the leafhopper Fieberiella florii have been reported in British Columbia and Ontario, although their efficiency to spread APP is unclear. There are no other known potential insect vectors of APP in Canada.

Does apple proliferation phytoplasma occur anywhere else in the world?

APP has been reported from many countries in Europe, including in the Balkans and southern Russia, as well as in Turkey and Syria. In Europe, APP is considered one of the most economically critical diseases of apple trees.

What should I do if I think my trees are exhibiting symptoms of apple proliferation phytoplasma?

Should you observe the symptoms of APP as described above, you should contact your local CFIA office or send an email to CFIAMaster@inspection.gc.ca

Are there any known treatments for apple proliferation phytoplasma?

There are currently no known treatments for this phytoplasma.

Does apple proliferation phytoplasma affect the health of humans or animals?

APP is a plant disease that does not affect the health of humans or animals.