Mysterious pathogenic apple killer !
April 21, 2019 09:27AM
What are they talking about here in the 2nd paragraph ?

[www.economist.com]

"Indeed, this is already happening in America, where a mysterious pathogen is killing apple trees..."

No mention of the killer (perhaps because it's that mysterious) but the author is certain that genetic tinkering is the answer to all of our c02 driven woes...

Josh Klatt
Ohio River Valley
Zone 6b
Re: Mysterious pathogenic apple killer !
April 21, 2019 04:01PM
Its pay-walled so I didn't read the whole article, but most likely they are referring to Sudden Apple Decline (SAD), also known as Rapid Apple Decline (RAD). SAD/RAD of course is not a single pathogen, but a complex of issues including a number of pathogens. I've heard this referred to as a disease or pathogen elsewhere, but the fact is that researchers don't understand everything that's involved or all the various interactions. I personally suspect that it is a combination of i) climate change, ii) more virulent common diseases, iii) appearance of relatively uncommon diseases, iv) overuse of herbicides, primarily Roundup and/or pre-emergents, v) resurgence of viruses (plus the appearance of at least one new one (luteovirus), vi) overuse of synthetic fertilizers.

Climate change plays a role by increasing survival, mobility, and insurgence of global pests, more variable weather throughout the year including milder winters, hotter drier summers.

Relatively uncommon apple diseases can include common forest pathogens such as schizophyllum that can infect trees stressed by climate change, insect attacks, secondary pathogens (such as those associated with black stem borer. As well, common soil disease (but not serious normally for apples) such as rhizoctonia, verticillium, fusarium, etc. Not to mention pathogens like the newly emerged Marsonnina leaf blotch.

Effect on root growth, soil microbiome, and general tree health is already well documented.

All common apple viruses plus luteovirus are becoming of greater to concern to pathologists. In addition to their general effect on apple trees, they also can affect graft union compatibility, resulting in reduced vitality, increased susceptibility to pathogens and insect pests, increased plant stress, and general malaise.

Synthetic fertilizers are salts. Salts kill things, disrupts soil microbiome, and encourage an imbalance is plant growth and development.

Anyway, there's more to this story obviously and researchers are picking up on more issues, but many still talk about it as a single organisms or factor. It's not .

Mike Biltonen, Know Your Roots
Zone 5b in New York
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