Pyrus calleryana

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Barb taught me how to id Virburnum tinus; now I have to learn to distinguish between Plums and Pears...

Hi

In a video a plant biologist said that some young Callery Pear leaves have three lobes. You can see three lobes on one of the lower leaves in the photo.

For the data:
Do you think this was planted deliberately, or sown by seed dispersal, or grown from a sucker?

Thanks
Kate

Kate
This is known to be a highly invasive species spread by birds. The street trees in the adjacent street are the source of the problem, created by ACT government promoting this species for urban use.
Barbara

Thanks Barbara

Yes I am very concerned about this species. We have wasted 27 years since it was first identified as a risk of becoming a serious environmental invasive weed in Australia https://weeds.org.au/wp-content/uploads/2020/04/potential.pdf
NATIONAL WEEDS PROGRAM POTENTIAL ENVIRONMENTAL WEEDS IN AUSTRALIA CANDIDATE SPECIES FOR PREVENTATIVE CONTROL By S Csurhes and R. Edwards

Our system doesn't declare plants to be noxious weeds until they impact agriculture, which will be far too late with this tree. If it gets any further it will be beyond the abilities and resources of landcare and bushcare volunteers to manage, beyond farmers, and probably beyond most councils and professional bush regenerators.

Very few people seem to be aware of how serious this weed will be, but I noticed that the Canberra group in Naturemapr are onto it. Nothing I am writing will be new to you, but I will write some here anyway.

I am gathering all the data I can find on naturalisations, and am collating a document of information which I will distribute to groups across Australia as ammunition to push to have this species banned before it is too late.

Ten years ago I managed to get a council in Sydney to stop planting Callery Pears as street trees and to take out the ones they had just been planting, but four other councils didn't respond, despite photgraphic evidence of their street trees suckering and it being explained that is one avenue of the fertilisation. Then I was busy with other things and have time now to try to stop it.

A weed ecologist in our NSW DPI has been trying to do something to stop them being planted since 2012, but without success, despite evidence that even then they were escaping around Grafton.

It is a popular plant and a money spinner for the horticulture industry who have been promoting it vigorously here since it started being banned in USA. So stopping its sale will need a lot of momentum, and even more to have the trees removed as people won't want to destroy their driveway avenues.

Each fertilised tree can produce thousands of seeds, which are almost 100% viable, and the majority of which remain viable for more than ten years. They produce chemicals which suppress the germination and growth of native trees in America and probably here, grow in thickets of large trees, then forests of those thickets, have spikes which go through shoes and even through tractor tyres. The impact on our wildlife and ecosystems will be catastrophic unless it is stopped.

We have the example of the temperate states in the US to show us, because they are about 20 years ahead of us in their widespread planting.

This is quite a good video of a researcher in Ohio https://www.google.com/search?q=USA+Callery+Pear+weed+problem&oq=USA+Callery+Pear+weed+problem&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIHCAEQIRigATIHCAIQIRigAdIBCjE2Nzc0ajBqMTWoAgiwAgHxBbHKWglC1puF&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:a447528b,vid:jUYvQvVtV6I,st:0

I would appreciate working with your group when I have put the document together, if you are interested.
Kate


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Katy I would be interested
abread111 perhaps a small para for newsletter; so good to hear that we are not the lonely fighters...

@Katy You can send the para for the newsletter to me at apm56@optusnet.com.au if you wouldn't mind. Thanks Alison

AlisonMilton sorry that was a misunderstanding:
I suggested to abread111 a para for the Friends of Mt Majura ParkCare group newsletter...
cc Katy

The Callery pears that the ACT Government plant on public land are raised in the Government nursery and so are the Callery pears that are included in a Government program to give free plants to domestic gardeners. The International Arboretum has a Callery pear "forest" one of the first that was planted. I remember vividly a speaker at a national weed forum in Canberra less then 2 decades ago who started his talk with the question why this highly invasive species was planted - I felt embarrassed on behalf of the Canberra community, the Goverment, and the many experts here in Canberra.

There are a few others who seem aware.

Victorian government 2018
https://www.ari.vic.gov.au/__data/assets/pdf_file/0027/125919/ARI-Technical-Report-287-Advisory-list-of-environmental-weeds-in-Victoria.pdf
Callery pear trees are listed in the Victorian Environment, Water, Land and Planning Dept's 2018 Advisory List of Environmental Weeds in Victoria Technical Report as highly invasive and very high risk as an environmental weed:

Landcare in Bungendore
https://www.treesforclimate.com.au/pyruscalleryana
Bungendore Landcare site says:
Pyrus calleryanas
Ornamental pear Pyrus Caleryana. Weed risk: Medium to high… Pyrus calleryana has become a weedy species in the USA and has some potential to become weedy in south-eastern Australia, especially in permanently damp locations… if growing with another cultivar or pear species, cross-pollination can lead to fruit production when insects can move between plants.
The small fruits are inedible to humans but attractive to birds, which eat and distribute the seeds across the landscape. Seeds that germinate develop into wild-type plants with poor form and thorns. They can form thickets and have broader ecological tolerances, allowing them to inhabit new regions… Suckering from rootstock can occur in stressed plants.

And an arborist in Adelaide
An Adelaide website: https://adelaidearborists.com.au/blog/trees-to-avoid-planting-in-your-garden-and-why-part2/
Trees to Avoid and Why Part 2
Callery Pear – This is a lovely tree that beautiful white flowers in spring and purple leaves in autumn. The problem is its branches are inertly very weak so it’s no good in windy areas or where there is snow. The Callery Pear and its cousin the “Bradford” are also considered invasive.

It takes a while to sieve through all the horticulture industry hype on the net, but there may be a few more Australian sites expressing concern, or at least wariness.

It is a strange phenomenon that despite what is happening in US, the authorities here choose to ignore it, and even ignore their own professionals like the weed ecologist in DPI.

Some horticulturalists think they solved the problem of the weak branching - the types they recommend now are less susceptible to this problem - hooray! let's plant them in the streets. In MIS 25 under Design Characteristics they list:
Aristocrat callery pear. Green
leaves turning red and orange
in autumn. Greyish-brown
bark. White flowers in spring.
Horizontal branches with wide
angles that are less likely to
split.

Capital callery pear. Narrow
fastigiated form. Green leaves
turning reddish-purple in
autumn. White flowers in
spring. Can be used as an
alternative to Lombardy
Poplar. Better branching
structure.

Cleveland select callery pear.
Green leaves turning red and
orange in autumn. Greyishbrown
bark. White flowers in
spring. Better branching
structure and less susceptible
to wind damage than other
Pyrus cultivars.

And all those cultivars are sufficiently genetically different from each other to be able to fertilise each other! Apparently there are more than 40 cultivars.