Page 310 - PC2019 Program & Proceedings

PLANT CANADA 2019

P193. Screening disinfectants for those effective against Plasmodiophora brassicae resting spores
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1
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Harding, M. ; B. Hill ; G. Daniels ; D. Burke ; R. Howard ; Chatterton, S.
1 Agriculture and Forestry
2
Alberta Agriculture and Forestry
3
RJH Ag Research Solutions Ltd.;
4 Agriculture and Agri-Food Canada
Clubroot is an important disease of canola caused by the protist Plasmodiophora brassicae. The pathogen
produces large amounts of small resting spores that can survive dormant in soil for many years. The
longevity of the resting spores makes management and containment of the disease very challenging. For
example, soil infested with resting spores is easily spread by farm and construction machinery. As a
result, equipment sanitization is an important method for preventing the spread of clubroot to new fields.
In order to understand which disinfectants could inactivate clubroot spores we evaluated disinfectant
efficacy using the Evans blue vital stain procedure. Of the 24 disinfectants tested, seven were able to
inactivate more than 95% of spores within 20 minutes of contact. The top two disinfectants were 2%
sodium hypochlorite and Spray Nine®. Other effective products were Adhere NC, Premise Degreaser and
AES 2500. Finally, ethanol and SaniDate® were also effective, but only at concentrations above 75% and
90% respectively.

Syama Chatterton (syama.chatterton@canada.ca)

P194. Apple and apricot decline in Ontario
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1
Griffiths, J. ; A. Lofano ; O. Ellouz ; A. Wang
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1 Agriculture and Agri-food Canada
2 Agriculture and Agri-Food Canada; University of Western Ontario

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.

Jonathan Griffiths (jonathan.griffiths@canada.ca)

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