D-97-03

Our File
3525-11F1-0/3525-11F1/FN7
3510-3-1B1

I. SUBJECT

This directive conveys the decision to remove Colletotrichum acutatum, as a quarantine pest for Canada.

This directive supersedes the memorandum to Regional Program Managers Plant Health dated January 30, 1991, entitled "Interception of Colletotrichum acutatum on Fresh Blueberries from New Zealand".

II. BACKGROUND

C. acutatum causes berry rot in blueberries and is one of the fungi causing strawberry anthracnose. C. acutatum f. sp. pinea causes terminal crook disease in pine and hemlock seedlings.

Phytosanitary measures have been taken on various occasions by Agriculture and Agri-Food Canada (AAFC) on commodities infected with Colletotrichum acutatum. For example, shipments of fresh fruit entering Canada, e.g. blueberries from New Zealand, found infected with this fungus have been refused entry. Tsuga heterophylla (western hemlock) seedlings found infected in a British Columbia greenhouse in the early 1980s were destroyed.

At the time these phytosanitary measures were taken, there was uncertainty regarding the distribution of C. acutatum in Canada. Since that time, however, the disease has been reported in a number of provinces, including Nova Scotia, New Brunswick, Quebec, Ontario, Manitoba and British Columbia. The disease occurs in many areas of the United States (U.S.), including those areas from which large volumes of strawberry plants are imported annually. Presumably, with the large volumes imported, the fungus has been introduced into Canada many times.

There was also uncertainty regarding the economic significance of the disease to Canada. Since that time, however, pest risk assessments (PRAs) have been conducted which have concluded that C.acutatum causes minimal damage under Canadian climatic conditions. PRAs conducted relative to C. acutatum have included Colletotrichum acutatum Simmonds" dated June, 1990, "Anthracnose diseases of Strawberry", dated June 1990, "Colletotrichum acutatum f. sp. pinea" dated October 23, 1990 and "Blueberry Plants from Australia", updated August 2, 1993.

These PRAs found that hot, humid conditions, similar to conditions in southeastern U.S., are required for favourable development of the disease. Temperatures higher than 24°C and relative humidity greater than 90% are optimal.

C. acutatum causes serious losses to strawberry plants growing under hot, humid conditions. However, losses are generally minimal under the cooler and less humid conditions occurring in Canada. Somewhat more damage could occur on "everbearing" varieties, which are harvested later in the season.

C. acutatum f. sp. pinea usually only causes a temporary stunting from which the seedlings normally recover within the first year, either in the nursery bed or after planting out. Canadian climatic conditions may be unfavourable for establishment of the disease since the fungus failed to establish itself in B.C. in 1981 after 70,000 western hemlock seedlings later found to have originated from infected seedlots, were planted out on Vancouver Island.

It would be impractical and inappropriate to regulate this disease when it has already been reported from several provinces and when it is not expected to cause significant economic damage. C. acutatum is no longer considered a quarantine pest for Canada.

III. LEGISLATIVE AUTHORITY

The Plant Protection Act, S.C. 1990, c 22
The Plant Protection Regulations, SOR/95-212
The Plant Protection Fees Regulations, SOR/95-218

IV. DEREGULATED PEST(S)

Colletotrichum acutatum, Simmonds, including C. acutatum f. sp. pinea Dingley and Gilmour

V. POLICY

Colletotrichum acutatum is no longer considered a quarantine pest for Canada. This is to take effect immediately.

Quarantine action will no longer be taken on commodities found infected with this organism. No commodity will be regulated for this disease.

Dr. J.E. Hollebone
Director
Plant Protection Division

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