North American Fruit Explorers mailing list at ibiblio

[Elizabeth Hilborn <ehilborn@mebtel.net>]

Saw this today about sudden apple decline on my ID listserve.

Original article from:

https://www.growingmagazine.com/education/rapid-apple-decline-psu-remains-mystery/

Other links on topic at end of post.


   PRO/PL> Undiagnosed sudden decline, apple - USA
      (promed@promedmail.org)



Date: Fri, 29 Dec 2017 03:02:35 +0000
From: promed@promedmail.org
Subject: PRO/PL> Undiagnosed sudden decline, apple - USA
To: promed-post@promedmail.org, promed-plant-post@promedmail.org



UNDIAGNOSED SUDDEN DECLINE, APPLE - USA
***************************************
A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases <http://www.isid.org>

Date: Mon 25 Dec 2017
Source: Growing [edited]
<https://www.growingmagazine.com/education/rapid-apple-decline-psu-remains-mystery/>


In the Northeast [of the US], Canada and North Carolina, young dwarf trees in 
high-density orchards are dying [see ProMED-mail post 
http://promedmail.org/post/20100608.1911] with increased frequency.
The Pennsylvania Department of Agriculture, Cornell University, University of 
North Carolina and others have teamed up to solve the mystery of Rapid (or 
Sudden) Apple Decline (RAD or SAD).

There seems to be some connection to M9 rootstock, although other rootstocks 
also can be impacted. Fuji, Gala and Golden Delicious cultivars appear most 
susceptible. This might indicate some cultivar-rootstock combination 
triggering RAD. Observations do not point to any specific pathogen, abiotic 
factors may play a role, [but] there is no obvious common denominator among 
the impacted trees.

Trees, even those full of fruit, quickly die from RAD. The graft union shows 
necrosis [which] continues up the bark. Severe bark shedding near the graft 
union [and] cankers are also seen. Within 2 to 3 weeks, leaves turn yellow 
and the tree dies. There are few signals that anything is wrong prior to the 
sudden emergence of symptoms. Trees collapse completely, despite the wood 
being solid and the roots healthy. In any given block, trees with RAD are 
scattered with no pattern, [and] some trees can remain healthy.

Because stress is believed to be a factor in RAD, growers are advised to 
eliminate as many stressors as possible. Alternative rootstocks to
M9 could afford protection. Other [factors] may be playing some role in the 
syndrome and viruses or [other] pathogens - known or as yet unidentified - 
may also be contributing.

[Byline: Tamara Scully]

--
Communicated by:
ProMED-mail
<promed@promedmail.org>

[This undiagnosed disease or disorder in apple orchards was previously 
reported from Michigan and New York (ProMED-mail post 
http://promedmail.org/post/20100608.1911). It now appears to be much more 
widely distributed but unfortunately not much progress seems to have been 
made in the search for a cause.

Association with specific dwarfing rootstocks and apple varieties may imply 
graft transmissible agents such as viruses, viroids or phytoplasmas. 
Molecular methods are needed for their detection, but no information is 
provided in the report above whether a systematic molecular search for any 
pathogens has already been undertaken. As mentioned above, SAD may also 
represent a syndrome including a number of different factors, which would 
make the task of identifying a cause much more complex.

Generally, to identify a biotic or abiotic cause for a disease or disorder of 
unknown aetiology, a defined process must be followed:
description of specific symptoms in individual plants; patterns of their 
distribution in space and time; evidence for or against transmission of 
symptoms and spread of the condition; Koch's rules (i.e. to re-isolate an 
infectious pathogen after culture and transmission, or equivalent process for 
non-culturable pathogens) to test for causation by a biotic agent; molecular 
studies to identify a known or characterise a novel potential infectious 
agent. Especially in slow growing hosts, such as trees, this process may take 
many years and it would be complicated considerably if a previously unknown 
pathogen were to be involved.

Maps
USA:
<http://www.mapsofworld.com/usa/usa-state-and-capital-map.html>
Individual states via:
<http://www.mapsofworld.com/usa/states/>

Pictures
SAD symptoms:
<http://www.goodfruit.com/wp-content/uploads/rapidAppleDecline1010442-1-1-620x465.jpg>,
<https://www.agprofessional.com/sites/default/files/image_galleryzoom_1.jpg>,
<http://www.omafra.gov.on.ca/english/crops/hort/news/orchnews/2016/on-1216a6f3.jpg>,
<http://www.goodfruit.com/wp-content/uploads/rapidAppleDecline1010428-2-620x727.jpg>,
<http://www.mpnnow.com/storyimage/NU/20171211/NEWS/171219934/AR/0/AR-171219934.jpg>
and
<http://files.growingproduce.com/growingproduce/wp-content/uploads/2017/08/tree-decline-new-york.jpg>

Links
Additional news stories:
<http://www.freshplaza.com/article/186470/New-York-state-experts-probe-sudden-apple-decline>,
<http://www.mpnnow.com/news/20171211/experts-probe-sudden-apple-decline>,
<https://www.agprofessional.com/article/rapid-apple-decline-hits-trees-northeast>,
<http://www.goodfruit.com/whats-killing-these-trees/> and 
<http://www.lancasterfarming.com/farming/produce/mystery-issue-killing-apple-trees/article_fd8cbacf-57fc-5af8-9a4f-486faca643f6.html>
Information on SAD:
<https://extension.psu.edu/rapid-apple-decline-rad-or-sudden-apple-decline-sad>,
<http://www.omafra.gov.on.ca/english/crops/hort/news/orchnews/2016/on-1216a6.htm>,
<http://www.hort.cornell.edu/expo/proceedings/2017/TreeFruitPestMGMT.AppleTrunkDisorders.Rosenberger.2017.pdf>
and
<http://www.growingproduce.com/fruits/apples-pears/new-york-growers-input-needed-on-tree-decline/>
Information on apple rootstocks, including M9:
<http://www.gardenaction.co.uk/fruit_veg_diary/fruit_veg_mini_project_september_2a_apple.asp>.
- Mod.DHA]

[See Also:
Crown & root rot, apple - USA: (eastern)
http://promedmail.org/post/20170821.5263568
2016
----
Fireblight, apple - Canada: (QC)
http://promedmail.org/post/20160919.4500366
2014
----
Fireblight, apple - Canada: (NS)
http://promedmail.org/post/20140908.2756240
2013
----
Apple proliferation phytoplasma- N America: 1st report, Canada
http://promedmail.org/post/20130415.1646164
2012
----
Fungal diseases, apple - USA: (NY, MI)
http://promedmail.org/post/20120906.1282861
2010
----
Undiagnosed mould & scab, apple - Mexico (QE)
http://promedmail.org/post/20100822.2939
Undiagnosed disease, apple - USA: (MI, NY)
http://promedmail.org/post/20100608.1911
and additional items on apple diseases in the archives] 
.................................................sb/dha/ec/lm

------------------------------

*##########################################################*
************************************************************
ProMED-mail makes every effort to  verify  the reports  that are  posted,  
but  the  accuracy  and  completeness  of  the
information,   and  of  any  statements  or  opinions  based
thereon, are not guaranteed. The reader assumes all risks in
using information posted or archived by  ProMED-mail.   ISID
and  its  associated  service  providers  shall not be  held responsible for 
errors or omissions or  held liable for  any damages incurred as a result of 
use or reliance upon  posted or archived material.
************************************************************
Donate to ProMED-mail. Details available at:
<http://www.isid.org/donate/>
************************************************************
Visit ProMED-mail's web site at <http://www.promedmail.org>.
Send all items for posting to: promed@promedmail.org (NOT to an individual 
moderator).  If you do not give your full name name and affiliation,  it may not be 
posted.  You may unsub- scribe at  
<http://ww4.isid.org/promedmail/subscribe.php>.
For  assistance  from   a   human   being, send mail to:
<postmaster@promedmail.org>.
############################################################
############################################################

List-Unsubscribe: http://ww4.isid.org/promedmail/subscribe.php


End of ProMED Digest, Vol 66, Issue 83
**************************************