In my last essay, In Defense of Bradford Pear, I showed the above chart from Australia that correlated fruit size with bird species. Similar charts or descriptions have been found in publications from New Zealand, Spain, Japan and in the US, as well. Based on the correlation of fruit consumption with fruit size, I’ve decided to elaborate on the last essay in order to practically address Callery/Bradford pear invasiveness in the US in the best way I can.
Due to Callery’s fruit size attracting our native songbirds, like American robins, cedar waxwings and gray catbirds, we can’t stop them from eating the little pears and pooping in marginalized areas like fencelines and worn out pastures. To think we can kill enough Callery pear to make a difference is a lesson in futility because 1.) We live in the United States and you can’t go kill a neighbor’s tree in the name of INVASIVES if they don’t want you to and 2.) Each tree produces thousands of fruits. So, with that said, here are my top solutions to sustainably make Callery pear less invasive and more useful.
1.) Citizen Breeding. What makes Callery pear invasive is its ability to produce copious amounts of small fruits, which birds then eat and distribute all over the place. It seems logical, then, to want to try and breed larger fruits into our populations of Callery in order to stop the spread by birds. In order to reduce invasiveness by around 80%, all it takes is getting progeny from the Callery/Bradford trees to produce fruits that are around an inch (25mm) in diameter. How do we do that? Allow them to hybridize with larger fruiting pears so the seeds dispersed by birds will have a higher likelihood of growing larger fruits…thus halting the invasion cycle.
What is needed to hybridize these pears and get them larger? For starters, you’re going to need a collection of pears that bloom at the same time as Callery, which is quite early. Russian/Cold Climate and early Asian pears are likely your best bet for this, so I went through the GRIN database (taxpayer funded genetic repositories) and have made a starter-list (there are a bunch more):
PI 541904- Seuri Li
PI 45845- Yaguang Li
PI 437051- Jubilee (cold hardy)
PI 541925- Kor 2
PI 267863- Pingo Li
PI 134606- Tioma (cold hardy)
PI 278727- La Providence
PI 278731- Sivaganga Estate
PI 307497- Seu Ri
PI 292377- Ranniaia Mleevskaia (cold hardy)
PI 541760- Chieh li x Japanese Golden Russet
PI 278729- Samy’s Estate
PI 541761- Chieh Li x Japanese Golden Russet 2
PI 541905- Szumi
PI 127715- Krylov (cold hardy)
PI 541326- Angelica Di Saonara
PI 324028- B-52 (cold hardy)
PI 541290- Mag 1 (cold hardy)
PI 132103- Shu Li
PI 312509- Tse Li
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You can request free scions online from September 1 to February 1 of every year from GRIN. You can also probably buy many of these cultivars online. From there, I highly recommend you share scions of these for free every winter, as I plan to do, in order to help infuse larger fruiting genetics into Calleryana.
You might notice there are a bunch of Asian pears in that list and you might think: Eliza, those pears are super fireblight susceptible! And you are right, of course, but think of it this way: MANY trees that are listed as fireblight susceptible are actually quite tolerant to FB once they are established and reaching sexual maturity. With Callery being an amazingly fireblight tolerant rootstock, this should help to get your topworked trees past the first 2 years of heightened susceptibility so they can start to fruit. Once these Asian pears intermingle with Callery, there are two possible outcomes:
1.) The hybrid offspring are more fireblight tolerant than the grafted Asian pearent’s tolerance
2.) The hybrid offspring is less tolerant to fireblight than the grafted Asian parent’s tolerance and will probably succumb to the disease and die on its own.
Either are a win-win, really.
Next, you’re gonna need to go into your pear thicket and do some cutting and grafting. There are two scenarios I see often:
1.) Field full of Callery: If you have a thick field of calleryana, I would recommend getting a forestry mulcher in and cut/mulch rows into the existing Callery stand. Then, run the mulcher to cut out trees within the rows left standing so the remaining are at 15 foot spacings. Top the trees you’ve left behind above deer browse ( throw into the alley and run over those, too, with the mulcher) and graft on the early blooming large fruited cultivars.
2.) Fenceline/Border with Callery: This is the scenario We’ve been dealing with over the past few years along the farm fenceline. First thing I do is flag the trees I want to keep, which are at 15 foot spacings along the fence. Then we cut out and chip all the non-flagged callery trees using my neighbor’s chipper (I mulch my orchard with callery pear wood chips). While we are cutting out the non-flagged trees, I go ahead and also cut the tops out of the flagged trees. I pick a height that is above deer browse height and also has a lot of clear wood without branches, because that helps with grafting. In April (I’m in zone 7a), I make fresh cuts on the remaining pear trees and topwork all of them to fruiting cultivars. We’ve been doing this for 3 years and 2018’s topworked pears will be producing fruit this year.
This is totally doable and the result? An orchard of pears! You’d have to cut the tree down anyway if you were going to spray it, so why not turn it into a producing pear tree of value? My neighbors even pitched in to help us cut and chip in the name of supporting my vision and also getting rid of the fruiting portion of the Callery trees.
In two years, your top-worked pears will be flowering and the bees will mingle between surrounding landscape Callery/Bradford pears that weren’t able to be cut down and the large-fruited cultivars you have grafted. With callery pears being pollinated with the list of pears above, your chances of getting larger fruit to come up from the fertilized seed will exponentially increase, limiting its invasiveness if the fruit is an inch or larger in diameter.
2.) Use them as rootstocks! Every Callery pear growing is automatically the best pear rootstock around. For all of you people out there who are inundated with deer pressure, graft to the Callery pears to any pear you’d like (or Winter Banana apple) above the deer browse line. Sure, you’ll get lots of leafy re-growth off the trunk for a few years (which the deer or other livestock eat as tender shoots), but its also really easy to remove new growth with your hands or slightly older growth with pruners, and new shoots don’t have thorns. You’ll start to get fruit in 2-3 years.
One of the main reasons why Callery didn’t catch on as a rootstock, aside from root propagation failures and hardiness, is that they don’t produce dessert fruit (fruit meant for out of hand eating). This is the same reason why we’ve lost SO MANY fruit cultivars in the last 100 years. If you weren’t a dessert cultivar chosen by the cooperative extension to be grown in the early 20th century, you were phased out. However, in today’s markets, I believe large fruited Callery pear hybrids really have a chance in fermentation, specifically cider blends and perry (cider made from pears). They are high in sugar (over 16% brix on average for the 200 or so hybridized trees I’ve evaluated), and run the gamut in acidity, tannins, aromatics and unusual characteristics. Since these trees are so disease and pest tolerant, which allows them to grow and produce copious amounts of fruit without the hand of humans or chemicals, they stand to produce the most sustainable fruits and alcohol in humid temperate climates. We need more people working with them in order to make this happen because they aren’t apples and they need their own methods.
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The last essay left me with a bunch of hate mail and loads of baseless claims. In future essays, I’ll be debunking many of these claims in order to try and bring about a full picture. With that said, please send your strong opinions to firstname.lastname@example.org
Of Note: throughout the South and Southern New England, I have been noticing spontaneous hybridization in the “wild” between P. calleryana with P. communis (French) and/or P. pyrifolia (Asian). These trees have much larger fruits, usually golfball sized or larger, and are often loaded with fruits dripping from the trees because Callery genetics are heavy lateral bearers (perhaps an indicator phenotype for these hybrids). No research that I can find has evaluated the genetics of these larger fruited callery-like pears to see what exactly they are crossed with, but I’m happy to help supply specimens if anyone out there takes an interest.
One thought on “How to Make Bradford/Callery Pear Less Invasive.”
Thanks so much for all of your research and for posting this, Eliza! I have a ton of these seedling(many of which are thorny) pears on my property, which is an abandoned farm field. I was contemplating grafting them over to cider pears but wasn’t sure if that would work. Your article has inspired me to try this plan out. Going to order pear scions this winter and I’m going to graft every last one that I can find over into cider and dessert pears. Thanks for the tip!