Plum Pox Virus in Canada Blake Ferguson Canadian Food Inspection Agency

1. Plum Pox Virus in Canada Blake Ferguson Canadian Food Inspection Agency

2. Plum Pox Virus • Plum Pox Virus (PPV) is a virus that infects plants in the genus Prunus - plums, peaches, apricots etc. • It causes a disease called plum pox or sharka. • Plum Pox is the most serious disease of stone fruits in Europe. • The virus has several strains : D, M, C, W and EA strains.

3. Distribution in the World • First found in Bulgaria around 1917 • Now present in most European countries • widespread in central & eastern Europe • recently reported in Mediterranean countries • sporadic reports in northern Europe • Also in Egypt, India, Syria, Turkey, Argentina & Chile • 1999 - Pennsylvania, USA, strain D • 2000 – Canada, strain D

4. Background • Plum Pox Virus (Sharka) • Decrease yield & fruit quality • Transmitted via aphids or propagation • Transmissibility and host range vary by strain • Severe economic impact

5. Host Range • Hosts are mainly in the genus Prunus • Both fruit stock and ornamental plants may be infected • PPV affects plums, peaches, nectarines, almonds, cherries and apricots • Wild Prunus species are also hosts • Some herbaceous weeds can be infected

6. Stone Fruit Production in Canada Canada’s Commercial Production of PPV-D susceptible stone-fruit • Ontario 77% • British Columbia 21% • Nova Scotia 1.1% • Quebec 0.6%

8. PPV survey in Canada2005

9. (2004) (2003)

10. = 2004 Survey = 2005 Survey = Positive Samples 24 Positives on 19 Properties (2 properties not shown on map) St. Catharines

12. Total Ontario Samples Collected 1,041,442

13. Positive Blocks - Ontario % infested blocks 2000: 246/5121 4.80 % 2001: 211/6125 3.44 % 2002: 215/7474 2.88 % 2003: 235/7911 2.97 % 2004: 302/8158 3.70 % 2005: 168/7293 2.30%

14. Positive Blocks - Ontario

15. Total positive blocks Total positive trees Number of samples collected

16. Aphid transmission of PPV 2004 evidence • Volunteer seedlings found to be infected • Newly planted blocks propagated from PPV-tested budwood have been found to contain infected trees • Research indicates peach to peach transmission rates as high as 22% using 50 Myzus persicae aphids per plant 2005 evidence • 5 residential trees grown from seed were found positive • 103 existing orchard blocks becoming positive after 4-5 years of negative testing.

17. Niagara Repeat Positive Blocks * In at least one subsequent year. **51% of positive blocks are repeat positives in subsequent years.

18. Current challenges • Continuing discovery of newly positive blocks • Availability of tested/certified replacement trees • Clearer data needed on aphid spread of PPV • Resistance of growers to mandatory block removals • Need to consider buffers but • logistical difficulties • industry structure considerations • neighbour effect