Pear tree Fireblight research so you dont have to


#1

I’m constantly looking for fireblight research information for pears and coming up without adequate information so I wanted to share what I’ve found. Please add to it if you can especially if you have grown varieties not mentioned that are resistant or if you know some mentioned are not. The three main types of pears we can grow are european / french (not fire blight resistant), Oriental hybrids like Kieffer, douglas, orient etc. which are crossed with sand pear and are resistant to fireblight , Asian Pears (like Korean Giant,chojuro etc. mixed rating on fireblight suseptability). I’m not sure all of the pears which are Fireblight resistant because there are around 5,000 types of pears.

Many pear rootstocks are very resistant to fireblight. To name a few of those resistant rootstocks OHxF333,OHxF40,OHxF87,OHxF97 are the most common. Those Old Home x Farmingdale rootstocks were specifically bred for the purpose of fireblight resistance. There are other rootsocks used for a variety of reasons such as Hawthorn,Betulifolia, Winter Nelis, Pyrus calleryana aka callery, Pyrus ussuriensis aka harbin pear. New varieties of rootstocks such as Pyrodwarf,Pyro 2-33 are quickly becoming available and have some promising features. So where to buy rootstocks? sierragoldtrees.com,copenhavenfarms.com, cumminsnursery.com, burntridgenursery.com, willamettenurseries.com, lawyernursery.com to name a few. Stay away from any pyrus communis or quince in my understanding as they are not fireblight resistant. I would like to discuss rootstocks more but lets just say generally people buy them for price, scion compatibility, soil, drought, dampness, and disease tolerance, and age the rootstock influences fruit bearing. So pyro rootstocks might be bought because they bear in a couple of years but cost $4 each if
bought 100 at a time. Betulifolia aka bet rootstock is highly compatible with asian pears cost $1 each but sucker like crazy.

Some nurseries appear to specialize in fireblight resistant pear trees for wildlife use such as http://www.wildlifegroup.com/shop-for-pear-trees. Fireblight is a bacteria called Erwinia amylovora. I treat Fireblight using several methods but none of which are great 1.) Spray with copper 2.) Spray with 50/50 white vinegar and water solution 3.) Spray with Antibiotics 4.) If all else fails amputate the branch or remove the tree 5.) Plant resistant pear trees. Some varieties of pears are more resistant than others as mentioned above which are mostly european crossed with sand pears. Some have no flavor or a gritty texture and others are very good. Kieffer and pineapple still get fireblight but I’ve never heard of them dying from it so they really are resistant. Pears such as the ledbetter on the wildlifegroup.com website are reported to not get fireblight at all. The wild callery in this area do not have a spot of fireblight. The problem is pears such as my bartlett are not really resistant it just blooms early and dodges fireblight because of its bloom time. That’s true of seckel as well so if fireblight hits it it will hit it hard. Below is a list of the reported fireblight resistant trees some of which are and others which are not in my area.

Magness
Maxine
Moonglow
Maxine
Warren
Orient
Kieffer
Ayres
Nova
Pineapple
Turnbull
Clara Frijs
Garber
LeConte
Monterrey
Honeysweet
Harrow Delight
20th Century
Shinsesik1
Seckel
Douglas
Duchess
Blake’s Pride
Hood
Monterrey
Potomac
Shenandoah
Ure


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#2

The list of rootstocks and pears resistant to Fireblight is long and I have not been through all of it. I’m not 100% sure all qualities have been noted because private and government information does not always match, here is a list provided by ars http://www.ars.usda.gov/SP2UserFiles/Place/20721500/catalogs/pyreurop.html


#3

Great post. Fireblight can be difficult to manage without resistant varieties. The good news is that there are several high quality pears with resistance. My current grafts are from Orient, Moonglow, Seckel, Kieffer, Ayers, Hood, and Olympic. Bill


#4

I’ve been lucky so far; I’ve had a few tiny strikes but nothing that needed anything beyond minor pruning.

I have a hunch that a lot of the fireblight susceptibility issue depends on the timing of a number of different factors coinciding just so. Time of bloom and weather conditions at bloom are two of the more obvious. What I am suggesting is that a cultivar may be resistant in one part of the country but not in another. Given the possibility of a changing climate today’s hero could be tomorrow’s goat, and vice versa.

If my hunch -and that’s all it is- has any merit to it than we have to view any history we study with reservation, which makes everything harder!


#5

If anyone has more info on the Asian pears please let us know. I have heard the more FB resistant Asians are chojuro, kikuzi, kinsui,seuri, shinko, shinsui, singo, tsu li. I have heard like Bartlett and seckel Korean giant has a bloom time that may prevent it from getting FB.

A non Asian pear that is reportedly fb resistant i know little about is golden spice.


#6

I appreciate you sharing your research. I hope to learn from your field trials as well. Finding 50 varieties of pears that do well in this climate will be no small task. I’m looking forward to borrowing some pear scion from from my friend Clark in a few years who put in all the work :stuck_out_tongue_closed_eyes:


#8

Usually someone asks about the sand pear that Peter Kieffer used to make the Kieffer pear cross and it was pyrus pyrifolia and the other parent was likely Bartlett . Bartlett is also known as Williams.


#9

I have Blake’s Pride, Harrow Sweet, 20th Century, Korean Giant and Hosui.

Only 20th C got blossom blight. The blossoms on that branch got wiped out by blight that wet spring. The branches was not affected.

Otherwise, nothing got blight. The trees are from 3-8 years old.

Pear blister mite is another story :slight_smile:


#10

The link below is an excellent list of Fireblight resistant pears. If doing research scions may be available http://www.ars.usda.gov/SP2UserFiles/Place/20721500/catalogs/pyrblres.html


#11

Nice find Clark. Is there a way to order pear scion from the usda?


#12

My Bartlett had fire bought this year and last. I haven’t seen it referred to as FB resistant though.

Like Marknmt said, I suspect one of the biggest factors is where you live. Seckel is supposedly resistant, but the last two years I’ve seen FB on the Seckels at the local nurseries. It didn’t inspire a lot of confidence.

Anyone else in coastal California have as many issues with FB as we seem to have in the Bay Area? Even in the parking lot where I work there was an especially bad strike on some ornamental pears. Several of them died.


#13

You should read up on this page http://www.ars.usda.gov/Services/Services.htm?docid=11896 because if it’s for research or education they will send out scion wood free of charge. They also offer very useful information. In my case I’m going to try to analyze 50 or so varieties and try to determine a marketable pear for this area. I need to determine not just fire blight resistance but bloom time, taste, rootstock compatibility, bearing age per scion etc. and unfortunately the information is unavailable for this area. No one here grows pears professionally. The pears that are grown here are not marketable or fire blight resistant. Once I’ve determined what I can grow I will compare numerous rootstocks and compare yield per rootstock, average pear size and other information. Root stock is said to influence pear size according to some sources. I’ve been teaching my neighbors to graft in the process of analyzing pear varieties that could be used as a crop in this area.


#14

Bartlett like seckel is actually not fire blight resistant in any way other that bloom time. Since FB is spread when a point of entry is exposed it can be spread by bloom. As bees move from a tree without FB to a tree with FB if weather is conducive to the spread of FB the bee will carry that infection to the uninfected tree. Bloom time is a primary factor of research for me in Kansas because it is the primary source of fire blight http://blogs.cornell.edu/plantpathhvl/apple-diseases/fire-blight/. As mentioned in the article from Cornell FB only affects pear tissue that is growing. So when people say Pyrus communis L. pears like seckel and Bartlett are resistant keep in mind they are only talking about the bloom time so if in your area weather is conducive to FB when those varieties bloom they will absolutely get FB if the bacteria is present.

There are always exceptions to every rule but for our purposes now lets assume Pyrus communis L. is susceptible to FB. Note on this link http://www.ars.usda.gov/SP2UserFiles/Place/20721500/catalogs/pyrblres.html the varieties specifically that are called Pyrus hybrid. What is a hybrid your likely asking? In many but not all cases of FB resistant pears it is Pyrus communis crossed with Pyrus pyrifolia . Pyrus pyrifolia is the sand pear that gives the sandy texture to kieffer and other pears that are hybrids. The sand pear information can be seen here https://plants.ces.ncsu.edu/plants/all/pyrus-pyrifolia/. Pyrus pyrifolia is for the most part Fire blight resistant but again remember there are exceptions.

I would recommend reading up on pear rootstocks http://county.wsu.edu/chelan-douglas/agriculture/treefruit/Pages/Pear_Rootstock_Research_Project.aspx . Recall earlier I said there are always exceptions to rules and Pyrus communis has a couple. Rootstocks were developed with Pyrus communis L aka “old home” and " Farmingdale" http://www.ars-grin.gov/cor/cool/pyr.oldhome.html. The rootstocks ohxf get their name from that cross.


#15

Clark,

I have two Bartletts. One is a Max. Red Bartlett and one just a regular Bartlett. A few years ago the Red Bartlett got fireblight and took out about a third of the tree. This year the regular Bartlett got fireblight bad enough that it’s pretty much dead.


#16

Thanks Olpea for the information. Fireblight seems particulary bad lately here in Kansas due to weather and cicada damage. Ive made a conentrated effort to start growing more hybrids like douglas and less early blooming varities like bartlett and seckel. Let me know if you need scions and i can send you some.


#17

Want a nearly 100% fireblight, disease resistant pear ? Maybe if your looking for something to make into perry or looking for a pollinator thewild pear may fit your needs for fireblight resistance. If you live in zone 6-9 see this link www.nativnurseries.com/p-51-wild-deer-pear-pyrus-communis.aspx . looking for fireblight resistant hardy pear rootstock that can grow in zone 5 or colder? I bought some wild pears a year or so ago and they have so far shown no signs of any disease or insect damage http://oikostreecrops.com/products/edible-fruits/wild-pears/.


#18

Have you heard of the 65/65 rule? If not it means 65° F and 65% humidity = perfect fireblight conditions. Recall experts know fireblight only attacks actively growing pear trees. Make sure to not prune during times when the pear is growing. If i must prune i quickly cover the wound with indoor paint or tanglefoot during fb season. Some people spray the tree with streptomyacin during those 65/65 conditions if the tree is particularly susceptible. Below is a partial list of Fireblight resistant varieties from the website http://www.ars-grin.gov/cor/catalogs/pyrblres.html. Even with the extremely resistant varieties my recommendation would be to do most of your pruning in the dormant season before FB becomes active. That also means graft a little earlier. I wanted to post an easier to read partial list as the information can be very difficult to obtain.
PI 541179 Duchesse Bronzee - COR - Pyrus communis
PI 541188 Farmingdale - COR - Pyrus communis
PI 541217 Lincoln - COR - Pyrus communis
PI 541231 Maxine - COR - Pyrus communis
PI 541306 Dabney - COR - Pyrus communis
PI 541336 Duchesse d’Angouleme Bronzee
PI 657922 Blake’s Pride
PI 541160 Cayuga - COR - Pyrus hybr.
PI 541311 Hood - COR - Pyrus hybr.
PI 541707 Cincincis- COR - Pyrus hybr.
PI 541708 Dixie- COR - Pyrus hybr.
PI 541709 Estella- COR - Pyrus hybr.
PI 541711 Garber- COR - Pyrus hybr.
PI 541712 Good Christian- COR - Pyrus hybr.
PI 541715 Richard Peters- COR - Pyrus hybr.
PI 541727 Sodak- COR - Pyrus hybr.
PI 541903 Monterrey- COR - Pyrus hybr.
PI 541954 Orient- COR - Pyrus hybr.
PI 617548 Spalding- COR - Pyrus hybr.
PI 617561 Pineapple- COR - Pyrus hybr.
PI 541208 Hoskins Pyrus communis
PI 541259 Saint Andre Pyrus communis
PI 541264 Snyder Pyrus communis
PI 541269 Sucre Verte Pyrus communis
PI 541280 Warner Pyrus communis
PI 541299 Magness Pyrus communis
PI 541315 Moonglow Pyrus communis
PI 541320 Honeysweet Pyrus communis
PI 541322 Luscious Pyrus communis
PI 541343 Mac Pyrus communis
PI 541345 Mericourt Pyrus communis
PI 541347 Moe Pyrus communis
PI 541350 Southworth Pyrus communis
PI 541388 El Dorado Pyrus communis
PI 541431 Harrow Delight Pyrus communis
PI 541448 Warren Pyrus communis
PI 541506 Tyson Pyrus communis
PI 617549 Morgan Pyrus communis
PI 617573 Carrick Pyrus communis
PI 617594 Potomac Pyrus communis
PI 541710 Eureka Pyrus hybr.
PI 617601 Tenn Pyrus hybr.
PI 541908 Okolo Pyrus pyrifolia
PI 654919 Singo Pyrus pyrifolia
PI 541998 Pai Li Pyrus ussuriensis
PI 541120 Ayer Pyrus communis
PI 541183 Early Harvest Pyrus communis
PI 541280 Warner Pyrus communis
PI 541431 Harrow Delight Pyrus communis
PI 541442 Atlantic Queen Pyrus communis
PI 541547 Golden Spice Pyrus communis
PI 617554 Bantam Pyrus communis
PI 541714 Kieffer Pyrus hybr.
PI 541722 Ayers Pyrus hybr.
PI 541723 Douglas Pyrus hybr.
PI 617642 Turnball Giant Pyrus hybr.
PI 641280 Ledbetter Pear Pyrus sp
PI 541303 Duchesse d’Angouleme Pyrus communis
I strongly suspect clara frijs is fire blight resistant because I have grown it in a highly susceptible spot with no signs of fire blight. I’m still testing my theory and wont know until it bears fruit for sure. By the way this link has some ripening times for some of these FB resistant pears that may be useful http://www.wildlifegrowers.com/QDMA_Pear_article.pdf


Stub cuts to encourage fruit bud development
#19

Fireblight resistance in pears does not neccesarily correlate to bad quality. Note pears such as magness, Ayers, duchess, harrow delight, Douglas, moonglow and many others consistently are reported as having a nice flavor.


#20

Wanted to mention matching disease resistance of pear varieties to actual diseases is important. This is why I feel test crops are critical. Scab, black rot and many other disease can be far worse threats in some areas than fireblight. In wet areas fungal diseases should not be disregarded. We focus on fireblight in this topic because its a main problem. Black rot as an example can easily jump from grapes to apples and pears which can be worse for an organic grower than fireblight. Black rot is active in this area at times. Clara frijs in my tests so far has been a winner for me. I’m not celebrating until I eat my first pear. Fireblight in the south and in this area is a terrible disease and by far the worse. Typically FB strikes during first fruit.


#21

Regarding asian pears, Shinko is extremely resistant to fireblight. I’ve had a tree for about 8 years and its never been hit. Even the Williams Pride apple next to it has had some hits. Shinko’s fruit is less rich in flavor than other asian pears, however, and the tree needs to be heavily thinned, as it is extremely productive.