Apple and apricot decline in Ontario


Griffiths, J., Lofano, A., Ellouze, W., Wang, A. (2019) Apple and apricot decline in Ontario. Plant Canada 2019, July 7-10. University of Guelph, Guelph, Ontario, Canada.


In Ontario, commercial fruit producers grow more than 450000 tonnes of fruit annually, with a total farm gate of over $225 million. As recently as 2014, an emerging and complex disease has been described that results in the rapid and sudden decline of apple trees (RAD). First reported in the United States, RAD has since been reported in Ontario and BC. The disease affects young (2-8yrs) trees, and is described by trees rapidly and unexpectedly declining over a period of two weeks resulting in death of the tree. Other symptoms can include dead tissue at the graft union that then proceeds up the trunk of the tree, and rapid reddening of the leaves over the two week period. Trees can collapse with a full load of fruit. A similar disease has recently been reported in other fruit trees including apricots, plums, and peaches. This second disease, which we are calling Tree Fruit Decline (TFD) occurs more slowly, over the course of two years, but also affects young trees. Up to 50% of newly planted trees can be affected by these diseases, and up to 10% of an orchard can be lost each year. The cause of these diseases is unknown. Here we report an update on the extent and symptoms of these diseases, as well as recent progress in identifying the cause of these diseases.