Corvallis diseased pear trees. No reason to worry!

I have just got a response from Corvallis on the diseased pear trees that they still distribute anyway.

He told me that in such a case of scion being distributed anyway it’s because there’s no risk to other pear trees, diseases that after the initial infection the rapid reproduction of virus cells then cease. Unlike fig trees, berries and stone fruits there are no insects around to spread these common pear and common apple diseases, and these allowed diseases can not be spread any other way besides insects. It would take insects that do not exist (at least in the USA, lets hope that nothing exists outside the USA) to start the rapid reproduction of virus cells again.

“Fruit tree material arriving from out of the country is subject to quarantine, and is cleaned up prior to release.” - Joseph Postman

“there are common “latent” viruses in most older fruit trees.” - Joseph Postman

“We don’t restrict distribution of material from the Germplasm Repository that is infected with common domestic viruses, but we do try to alert recipients when we know that viruses are present.” - Joseph Postman

“Historic varieties are almost all infected with one or more viruses, but in apples and pears they rarely produce symptoms” - Joseph Postman

@clarkinks the quarantine that you spoke of is over because it was a false alarm:

“Oregon imposed a quarantine on movement of certain plant materials because there were some positive tests for the bacteria Xylella fastidiosa from several pear trees in our collection in late 2015. Those tests turned out to be false positives and we have resumed distribution of scionwood.” - Joseph Postman

Yeah, they are sharing everywhere except for Oregon because state law requires 2 years of negative results following a positive.

(negative being good, positive bad, in this case :slight_smile: )


Corvallis lifted the quarantine as we were aware because we received scion wood. A presumed virus such as stonypit you get from an individual is something easily spread with a grafting knife in my opinion but I’ve never tried it. Corvallis is a source for scion wood for my farm because I think they are extremely reliable and credible. If they say there is nothing to be concerned about there is not. Many pear trees such as Doctor Deportes are virus infected which is not ideal but rather tolerable. I do grow that one as you may be aware. See this link Why are pear scions and rootstocks so hard to get this year? Quarantine is not just Corvallis

I agree they seem very knowledgeable as well as trustworthy and there is no need to spend time and money ridding of diseases that will do no harm, just the same I would clean the pruners after pruning because if I understand what Joseph Postman and the Internet says right, any virus can be spread by virus contaminated pruners and the initial infection is severe until the virus cells cease.

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Yes I know, I read that right before I started this thread.

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