[CANUFNET] Black knot problems in Edmonton

[pwynnyczuk at richmondhill.ca]

Quick note,
Many years ago I attended a meeting at a large reputable nursery  in 
Ontario,  and they indicated that part of the problem of black knot 
persistence  is the root stock.
I'm not an expert on growing,  this should be validated elsewhere,  but I 
sensed where the root stock is not Black Knot resistant and the top graft 
is, in some cases over time the root stock dominates leading to the 
reduction in resistance to the disease, infection from other sources 
occurs and the disease continues to spread.
As I understand most varieties are grafted, therefore growing industry 
quality control is the issue,

In Richmond Hill over the last 25 years, we experienced rapid population 
growth, and therefore tree plantings to match. We had  experimented with a 
couple of  Cherry varieties on a few streets.  Prunus padus (Developer 
Consultant suggestion back in the 1980's, 1 street planted and 
subsequently replaced with other species), and  Schubert Choke Cherry. 
We follow the appropriate control measures annually or semi annually but 
are finding  we  are  slowly replacing our Cherry trees once they reach a 
level of disease impact.  Criteria, basically disfigured, or structural 
issues.

Some residents are already sensitized by the almost annual Tent 
caterpillar event and subsequent  larvae with their webs, crawling on the 
driveways, and cocoon attachments they make on the exterior of their 
homes. 

Based on the above we are migrating other flowering species or alternative 
species over time.


Regards,
Peter Wynnyczuk

Urban Forestry Supervisor
Town of Richmond Hill
Parks, Recreation and Culture Department
Telephone:  905 780-2930
Fax:  905 884-0935
Internet: pwynnyczuk at richmondhill.ca




From:
Jim Donnelly <jdonnelly at cityofgp.com>
To:
"Canadian Urban Forest Network" <canufnet at list.web.net>
Date:
02/11/2010 10:11 AM
Subject:
Re: [CANUFNET] Black knot problems in Edmonton
Sent by:
canufnet-bounces at list.web.net



We have run a black knot program the last 10 years when southern Alberta 
started to have major issues. 
 
1.       We inspect all public cherries in early May (before leaf) and 
again in August (for new infections)
2.       If a plant is found we perform a concentric survey inspection of 
both public and private parcel cherries and hand out information leaflets 
to home owners
3.       We inspect all nursery stock we buy and what the local 
greenhouses/vendors buy in May
4.       When an infected tree is found we find out where the tree was 
bought (so far with the exception of a few Canadian Tire trees most have 
been from respectable nurseries)
5.       Amur still get black knot here
6.       We deal with the diseased wood the same as noxious weed seed 
heads. Landfill it and ask for ?immediate cover?
7.       Black Knot hasn?t been nasty enough here yet to trial any 
biological controls and most trees are found before more than a few 
braches need to be removed so tree mortality is at 1 or 2 per year.
8.       These measures have kept BK under control so far however the 
number of cases has doubled each of the last 3 years so what really has to 
happen is better regulation in the nursery trade. Hopefully the Nursery 
Certification Program continues to gather momentum.
 
 
Jim Donnelly
Integrated Pest Management Coordinator
Parks Operations
City of Grande Prairie, AB.
Tel:  780-513-5226
Fax: 780-532-7588
Cell: 780-814-3763 
jdonnelly at cityofgp.com 
 
From: canufnet-bounces at list.web.net [mailto:canufnet-bounces at list.web.net] 
On Behalf Of Trevor Thistle
Sent: February 10, 2010 1:42 PM
To: 'canufnet at list.web.net'
Cc: Kim Bendle; Costigan; Marshall Mithrush; Travis Kennedy; Rogers; 
Prutton; Megan; Dan Chouinard; Mark Wartenbe; Bonnie Fermanuik; Norm; 
Suzana Bodnar; Doug; John Helder; Bev Minsky; Guy Nighbor
Subject: [CANUFNET] Black knot problems in Edmonton
 
To Whom It May Concern:
 
For the past few years the City of Edmonton has been experiencing an 
outbreak of black knot (Apiosporina morbosa). Edmonton?s urban forestry 
unit, River Valley Forestry and Environmental Services (RVFES) has been 
responding by pruning out the visible fruiting bodies, and by removing 
trees that are beyond saving. However, if we continue these practices we 
will eventually end up removing thousands of our valuable ornamental trees 
of the genus Prunus. So, we are asking other municipalities about their 
experience with this fungal pathogen and what steps they have taken to 
battle black knot. RVFES would greatly appreciate if you could aid us in 
our fight against black knot by taking the time to answer the following 
questions.
 
·         Does your region have problems with black knot? If so do you 
have a campaign or strategy for combating it? If yes, how do you 
communicate your strategy to the public, and what do you do to encourage 
citizens to take care of black knot on their own trees?
·         If your municipality does treat for black knot, what treatments 
were and were not successful?
·         How serious is black knot mortality in your municipality?
·         Aside from Amur cherry, do you know of any black knot resistant 
varieties? Have you had success with any of these varieties?
·         How does your municipality dispose of infected material?
·         Has your municipality tried or had any success with the 
biological control agent, Trichothecium roseum (fungal parasite)?
 
 
Thank you for you time, 
 
Trevor Thistle B.Sc. (Forestry)
Urban Forester & ISA Certified Arborist
The City of Edmonton, Asset Management and Public Works
River Valley Forestry and Environmental Services
Email: trevor.thistle at edmonton.ca
Ph: (780) 944-7833
Fax: (780) 496-4978
 
 
 
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