The Coming Plague of Pears

sam_mdDecember 15, 2013

This post is in response to the ethics thread. In Oct 1999 Prince George's County MD Ext Agent Bob Stewart published this article about flowering pears which has been copied countless times:
The Coming Plague of Pears
While driving the Capital Beltway around Washington, D.C. this past April I began noticing a large number of white flowering trees in the areas just off the road. For the following three weeks I continued to see these same white flowering trees everywhere. They weren't dogwoods. They weren't wild cherries or shadblow Amelanchier. Finally, driving along route 450 in Bowie, my curiosity got the better of me and I pulled off the road and had a closer look at one of these trees. It was a pear. Not the common edible pear, Pyrus communis but the ornamental pear, Pyrus calleryana. It was obvious from where these trees were growing they weren't planned plantings. These trees were coming up wild and in tremendous numbers. In the spot in Bowie, I counted over one hundred trees in a stretch of neglected ground about 100 feet long and 50 feet wide. They were so thick that in places the individual young trees grew only a foot or two apart. We seem to have a new horticultural plague on our hands in Maryland, a plague of pears.
In 1918, the USDA was searching in China for improved root-stock plants for our commercial pear varieties. More than 100 pounds of Pyrus calleryana seed was brought back and sown at the USDA Plant Introduction Station in Glen Dale, Maryland. A vigorous, non-spiny seedling found among the normally spiny Pyrus calleryana seedlings was selected out and given the name Bradford. The Bradford Pear was quite a tree. It was fast growing, had dark, shiny leaves and had a wonderfully formal shape. It grew easily and was adaptable to a wide range of site conditions. It wasn't troubled by bug or disease, and it was loved universally by the nursery world, landscaper, and homeowner. In 1982, the National Landscape Association voted it the second most popular tree in America, just behind the flowering crabapple. Oh yes, there was another nice thing about the Bradford pear, since most trees were identical clones, propagated by grafting, it didn't self-pollinate and didn't produce fruit.
The Cinderella story of the Bradford pear ended once it was discovered that these trees begin to fall apart when they reach an age of about twenty years, right at the pinnacle of their landscape glory. The very narrow crotch angles of the erect and plentiful branches are weak, and a gusty thunderstorm or a coating of wet snow or ice will bring the branches crashing down. In an attempt to make a better Bradford there appeared a sucession of new callery pear cultivars. These had improved, or at least different branching patterns with at least less chance of the branch breaking problem. Now the Bradford was not alone. There were other callery pears in the landscape to keep it company. There was the Aristocrat pear, and the Chanticleer pear, and the Redspire pear. There was also something else.....cross pollination among the callery pears. Suddenly Bradford and the other pears began to produce fruit. True, the fruit was small, an inch or less in diameter, but some of the trees produced very large quantities of this small fruit. In some way, and I suspect it may be the birds, the seed within the fruit is being desseminated far and wide and new hybrid callery pears are popping up in every vacant lot and along every roadside throughout the area.
Whether or not a plethora of wild, ornamental pears is a plague depends on who eventually cleans up the ground on which they are raising up like new sown grass. Mowing over an overgrown patch of weeds is one thing; removing hundreds of four and five inch caliber trees is quite another. I live down the road a piece in Southern Maryland, and the other day I was picking up trash along the county road right-of-way in front of our house. Standing straight and tall out of the long grass and ragweed plants were two broomstick sized callery pear seedlings. The invasion is on.

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viburnumvalley(z5/6 KY)

Good work. I hope some of the histrionics of the Ethics post calm down upon reading that.

Here is another link with good research foundation and facts.

Here is a link that might be useful: History of Ornamental Callery Pear in US

    Bookmark   December 15, 2013 at 8:56PM
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toronado3800 Zone 6 StLouis(6)

Speaking of self pollinating... At work and in the abandoned commercial districts and neighborhoods left over from the crash and airport buyouts, the rootstock of the Bradfords have a good amount of suckers. I assume these will eventually flower.

Will the suckers pollinate the Bradfords?

This post was edited by toronado3800 on Sun, Dec 15, 13 at 22:29

    Bookmark   December 15, 2013 at 10:28PM
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viburnumvalley(z5/6 KY)

Yes, the suckering understock is genetically different from Bradford and any other clone grafted to it - thus making a perfectly fine pollination partner.

    Bookmark   December 15, 2013 at 11:05PM
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arktrees(6b NW Arkansas)

I've specifically avoided reading the ethics thread, as I knew when I saw it "Nothing good would come from that!"

Arktrees

    Bookmark   December 16, 2013 at 1:36PM
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hairmetal4ever(Z7 MD)

Callery Pears are basically the primary roadside tree around here - formerly treeless roadside land is now covered in them, along with some kudzu & only a scattering of native pioneer species like Juniperus virginiana and Red Maple.

    Bookmark   December 16, 2013 at 2:13PM
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j0nd03

At least around here, the rootstock commonly suckers regardless of whether or not the clonal scion is still alive which makes it basically self pollinating/fertile. The suckering is prob due to drought stress but whatever. It still can self pollinate if the rootstock suckers and flowers on its own.

Lack of pollinators is not really an issue now that the trees are literally as common as grass under power lines. The seed dispersed from perched birds en masse

    Bookmark   December 16, 2013 at 3:53PM
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alexander3_gw(6 Pennsylvania)

I took these pictures a couple years ago in the fall, all the red saplings are pear trees. This field is mowed once or twice a year, but you can imagine the pear forest it could become!

    Bookmark   December 18, 2013 at 10:58PM
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cousinfloyd

Great photo, alexander. Thanks for sharing.

    Bookmark   December 19, 2013 at 9:06AM
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bjb817

I would never plant a Bradford or related variety due to it being a poor long term investment and way overplanted in our area. That said, that amazes me how invasive they are in the mid Atlantic states. While I have seen them set fruit around here, I've yet to notice them popping up in greenbelts, roadsides etc... Maybe yet is they key word... I'm in Austin, TX.

    Bookmark   December 19, 2013 at 9:49AM
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j0nd03

Alexander, we have similar vistas as that picture down here in Arkansas as well unfortunately...

    Bookmark   December 19, 2013 at 11:30AM
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cousinfloyd

Callery pears do grow all over my place, similar to what's in the photo, just not nearly as thick. I do think it's nice to have root stocks already established with no work or cost to me all around my farm for any pear or Asian pear I'd like to have. And they mainly seem to be invasive in the pasture, where, like Alexander said, they get mowed and grazed enough not to ever cause me any trouble. (I know they're invasive in more significant ways in other kinds of places.) It's especially nice for all the areas where hoses can't reach and I can't practically water: it works a whole lot better to graft onto an established root stock than to plant a tree that I can't water. If a want another edible pear tree, I just find a callery seedling to let grow for a year (without mowing) and graft onto it the following year.

    Bookmark   December 19, 2013 at 1:22PM
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whaas_5a(5A SE WI)

Would the opinion be different if the plants didn't have a form that was so suspeptible to damage?

Luckily their spread is limited to open areas from what I know. But I can understand the issue with having unwanted seedlings scattered in areas you don't want trees growing....but this is the case for many junky trees, doesn't matter if they are native or invasive.

I struggle with whether you'd want barren roadside or pear trees, if they wouldn't be so suspectible to damage. Plague just seems a bit intense, but I'm sure its zone dependent.

I'm sure there is much more to it but just my off the cuff thoughts.

In my area I have much more of an issue with Populus deltoides. They grow everwhere...which is a problem because they are so big, so fast growing. They sallow all that is near. Oops, and they fall apart MORE so than pear trees. You cut em down, they grow right back over and over and over unless you chisel the trunk and apply round up. Luckily the damn thing doesn't grow all that well in shade. Same goes for Juniperus virginiana but they aren't as aggressive growing, and their vigor really drops off in shade. Throw in buckthorn, Robinia pseudoacacia and Acer negundo...now that a plague that pear doesn't even come close to.

    Bookmark   December 19, 2013 at 2:23PM
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j0nd03

Do any of those NATIVE trees you mentioned have 3" thorns ALL OVER THEM like the callery pears do???

You paid for and planted a clone of one so its pretty clear where you stand on the issue...

The ice storm we just had literally flattened countless pears to the point they look like a wagon wheel with a small 2-3' spoke connecting them to the ground. I have yet to see cottonwood damage and I have several around the house including a 20 footer of my own that had no damage and is completely out in the open. I sure don't think they (cottonwoods) are indestructible by any stretch of the imagination, but they are certainly more structurally sound than the callery pear

    Bookmark   December 19, 2013 at 2:37PM
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whaas_5a(5A SE WI)

Jon, don't worked up, I'm talking about my area only.

I really don't have a passionate opinon about Pyrus as they aren't a problem in my area due to hardiness but that doesn't mean I'm naive to the issues they really cause, ecpseically in areas where the plant is hardy.

Edit: Just for you, I'm going to take pics this weekend of the disatrous damage of just the few next door. They are all from seed from several mature specimens at a higher elevation and are choking out all the Oaks and Picea glauca. They snap on a regular basis from heavy wet snow and become more dense and shrubby. I'd don't mean to pick on the tree if it grows well for you, but they are choking out so many trees around here, that they piss me off to the degree that P.c does for you.

I always get a kick out the liabilities listed by the Uconn

Liabilities

do not plant near sewers, septic tanks, drains or sidewalks
suckers
canker
short-lived
too many to name

This post was edited by whaas on Thu, Dec 19, 13 at 17:40

    Bookmark   December 19, 2013 at 3:15PM
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alabamatreehugger(8)

I cut two wild ones down about 5 years ago, but I haven't found any since then. I think those may have been offspring from my edible pear, because deer like to eat the fruit before going back into the woods.

    Bookmark   December 19, 2013 at 7:55PM
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terrene(5b MA)

We have plenty of Callery pears growing in eastern Mass., they are a common landscape tree. I haven't noticed trees or seedlings in this neighborhood, or seedlings elsewhere, and hope it doesn't become a plague here. Pyrus calleryana is not on the Massachusetts Prohibited Plant list so apparently it has not presented itself as invasive in this state (as yet) and cultivars can still be purchased at nurseries.

There was a Bradford up at my rental house, but it had terrible form and narrow crotches, and was cut down 2 years ago. It's suckering a lot in the grass around the stump.

This post was edited by terrene on Thu, Dec 19, 13 at 20:47

    Bookmark   December 19, 2013 at 8:46PM
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j0nd03

Whaas, that is quite the list of liabilities hahaha

    Bookmark   December 19, 2013 at 9:25PM
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toronado3800 Zone 6 StLouis(6)

The whole invasive thing pushes them down the list for me.

If they were a weedy silver maple like native then so be it if ya plant a quick to split tree because you like it.

Mostly I do not expect folks to go remove their Bradford, just don't plant one and add to the problem.

    Bookmark   December 19, 2013 at 9:50PM
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Allen456(8)

I can't believe no one has mentioned the WORST feature of Bradford Pears.....the scent of their pollen!

    Bookmark   December 20, 2013 at 6:57AM
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hairmetal4ever(Z7 MD)

It does seem that at the edges of their hardiness range (z 5 mostly), the trees will survive went planted, but they don't get much of a foothold escaping from cultivation and becoming invasive.

In Austin (mentioned upthread), I'd bet seeds do sprout, but the heat and dryness in July/August probably kills the young seedlings even though a mature tree would survive the same conditions.

Here in the Mid-Atlantic they seem to just love our climate. Too much.

    Bookmark   December 20, 2013 at 10:05AM
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whaas_5a(5A SE WI)

They are listed as invasive here, I read the report on the species and they talked alot about IL. The seedlings are quite common in most all counties but mature specimens are hard to locate in IL. There are reports that it has escaped from cultivation in Kenosha county (WI) which is the most southerly county closest to lake MI.

Its unfortunate that the plant has wrecked havoc in some areas. I planted a Autumn Brilliance 8 years ago and selected it based on superior branching structure. At the time I really didn't know much about invasive species. Today it blooms like no other, very drought tolerant and fantastic red fall color. On the surface some clones are actually great trees.

    Bookmark   December 20, 2013 at 1:09PM
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Embothrium(USDA 8 Sunset 5 WA)

You must be thinking of 'Autumn Blaze'. 'Autumn Brilliance' is a service-berry.

    Bookmark   December 20, 2013 at 2:37PM
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whaas_5a(5A SE WI)

Right on, I actually planted an 'Autumn Brilliance' serviceberry that year as well.

    Bookmark   December 20, 2013 at 2:54PM
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sam_md

For the Pague of Pears to be realized there must be a source of seed right?
I took this pic this morning, this is just one of zillions of such innocent looking trees found in commercial and residential landscaping. Surely trees like this couldn't be the source of the plague? Right? :)

    Bookmark   December 21, 2013 at 1:18PM
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Embothrium(USDA 8 Sunset 5 WA)

Good things come in pears!

    Bookmark   December 21, 2013 at 2:36PM
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whaas_5a(5A SE WI)

Google "Spread and Ecological Impacts of Callery Pear"

Nice visuals in there. I saw the same thing in Indiana overhead with swaths of white when I was flying over this past spring.

    Bookmark   December 21, 2013 at 4:31PM
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Embothrium(USDA 8 Sunset 5 WA)

Apparently my post went overhead also.

This post was edited by bboy on Sun, Dec 22, 13 at 0:59

    Bookmark   December 22, 2013 at 12:43AM
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rusty_blackhaw(6a)

Since we've survived the plagues of Ailanthus and Paulownia ravaging our waste spaces and roadsides, I doubt that ornamental pears gone wild will do us in either.

    Bookmark   December 22, 2013 at 11:20AM
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toronado3800 Zone 6 StLouis(6)

Oh yeah, we will not die from them. Neither will my kid. I doubt in a long reaching time frame humans will be driven to extinction by them for as long as we are planning on guarding that nuclear waste in Yucca mountain or our neighbor's back yard or wherever. It just is not THAT pressing.

For a poor example that touches close to homes, I hear some folks get mad when you plant Bermuda of Zoysia next to their Fescue or Blue Grass yard. Lord forbid my neighbor decides to plant the wrong type of bamboo.

There is the more interesting example of when folks from China or St Louis travel to California they want to see Redwoods instead of Honeysuckle and Bradfords. When I drive through even close to home places like Ohio I expect to see Ohio Buckeye and Black Cherry along the roadsides not Bradfords and Honeysuckle or Paulownia.

But you are right, none of them are going to drive us to extinction and neither is letting me rezone my residential lot to industrial so I can chrome plate in my spare time and out compete the Chinese economically so help a brother out and write my representative!

    Bookmark   December 22, 2013 at 11:31AM
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brandon7 TN_zone(7)

Sometimes the impact of small things can result in huge outcomes later down the road. I can think of many things that are currently in the news that seemed very minor at first but are becoming more and more alarming (loss of honeybees, etc). Many of these things have no single cause, but result from a number of things adding up. Invasive populations are seldomly the only cause of loss of species but are a major contributing factor for many.

    Bookmark   December 22, 2013 at 2:05PM
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Embothrium(USDA 8 Sunset 5 WA)

I've seen the financial cost of invasive plants in North America said to be very high. Just looking at one aspect of this, it costs the farmer money to clear woody weeds out of a field they want to make use of. The profit margin is so low on many crops these days it seems to me that an added expense like this might be enough to make planting a field that has had to be re-cleared of trees and shrubs an unattractive prospect.

At least to the small, independent farmer.

This post was edited by bboy on Sun, Dec 22, 13 at 18:53

    Bookmark   December 22, 2013 at 3:07PM
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hortster(6a, southcentral KS)

bboy: "Good things come in pears!" That didn't go overhead, caught the gist of your altered adage. But the only thing good that I can think of at the moment is dead, cured pear wood for smoking meat...

hortster

    Bookmark   December 22, 2013 at 3:25PM
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kenptn(z6b TN)

Sam: Thanks for posting that image. I was afraid that the billions of European starlings wouldn't have anything to eat this winter and would starve.

    Bookmark   December 22, 2013 at 4:45PM
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calliope(6)

Yep, the good thing comes in pears gave me my first morning chuckle as well. Yesterday saw the tree gang hired by the power company reduce my one and only voluntarily planted bradford pear reduced to logs. They were eyeballing my privacy plantings of trees and shrubs between the front of my house and the road, specifically interested in my variegated sweet gum. I sent the mate out to talk to them and suggest they'd have a lot less trouble with it than the fifteen year old bradford I must have sited there during a brain fart storm. I was relieved when we gave permission to fell it and they accepted. It saved me the time and money to have it done and yeah.........I figured I better not miss that opportunity and jumped on it.

To be quite honest, I may have let it survive had I planted it anywhere else on the property. It had only been there about ten years, put on an astounding spring display and was lovely in every way but the crotch angle I didn't address when I should have. It was an impulse by someone who knows better, so I can understand its lure by others who might not.

    Bookmark   December 29, 2013 at 5:44AM
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BJSmith(7b)

I've heard bradfords being blamed for the increased incidence of fire blight down south. Is this true? My Dad hated the darned things. He always had a large veggie garden, but also nursed along several fruit trees, including a pear tree that we picked out together when first moving into the house some 35 years ago! When they didn't bloom, he didn't fuss too much. When it got sick, I think it about made him sick because he'd put so much effort into the pears the squirrels left for him. One of the last times I came home, he had a BB gun by the door just hoping to catch the squirrels in the act! (Think caddyshack, here!) Anyways, I've about decided to start my own orchard in the front yard. So....anyone got a BB gun? Not just squirrels here...We have DEER!

    Bookmark   June 30, 2014 at 10:45PM
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mosquitogang201

The developer in my neighborhood planted bradford pears at every house. Of those that haven't been cut down or blown over in a storm, all have fire blight. Doesn't seem to kill the trees but does make them look even uglier.

    Bookmark   July 1, 2014 at 10:12AM
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arktrees(6b NW Arkansas)

IMHO, Fireblight is adapting to attack and kill the callery pears (Bradford is one of these). There are simply millions upon millions of a few clones planted, and these are potential hosts. Not to mention the millions more offspring. Being so numerous, creates significant a selection pressure on the pathogen to adapt to attack them. It's a matter of time before these clones are wiped out. Classic host-pathogen dynamic.

Arktrees

    Bookmark   July 1, 2014 at 10:32AM
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BJSmith(7b)

I've been looking for a pollinator for an unknown Asian Pear. The nursery guy has advised that bradfords will pollinate other pears. Isn't that how the fireblight spreads? I'm a bit concerned. I have an unknown, barren seedling that's about 12 ft. tall, narrow in the center. It blooms, but does not produce. SO.....Can anyone tell me if planting another pear closer by will help keep the fireblight off the Orient Pear? Also, what to use for a pollinator as I have no idea what to plant as "Orient Pear" is a generic name for an Asian pear. There is no grower name on the label, nothing to identify the specific variety. HELP!

    Bookmark   July 1, 2014 at 8:03PM
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wisconsitom

Interesting about supposed invasiveness of B. pear in Kenosha county (Wisconsin). I know that city's Forester and he told me at last year's conference that pears are his favorite species to plant! I've got to talk to that boy! OK-I already did-but I better again.

+oM

    Bookmark   February 3, 2015 at 9:35AM
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lucky_p

BJS,
Fireblight was well-established in The South long before 'Bradford' came on the scene. Only iron-clad fireblight-resistant(not immune) cultivars survived.
All my life(nearing 60 years now), I've been seeing rugged old Keiffer pears at farmsteads with multiple FB strikes, going right along with their business of producing heavy crops of fruit; they just shrug it off and keep on going.

    Bookmark   February 3, 2015 at 11:16AM
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