UNDIAGNOSED DISEASE, APPLE - USA: (MICHIGAN, NEW YORK)

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A ProMED-mail post

ProMED-mail is a program of the
International Society for Infectious Diseases


Date: Sat 5 Jun 2010
Source: Chicago Tribune, Associated Press (AP)/Traverse City
Record-Eagle report [edited]



An unidentified blight is being blamed for the deaths of apple trees
in northern Michigan and researchers are working to determine what is
to blame. The disease has killed apple trees of 4 McIntosh varieties
grown from dwarf rootstock. Nikki Rothwell, Northwest Michigan
Horticultural Research Station, said the problem also is being
reported in western Michigan and in New York state. "We're seeing tons
of decline," she said.

"We have quite a few dying on us," said a grower in Williamsburg. The
disease has affected about 20 percent of his McIntosh crop, or about 3
percent of his total harvest. He worries that it might spread to other
trees. A grower in Northport said he has seen "scattered" attacks. He
said researchers took a chunk of one of his dead trees and are
investigating possible causes. "Some part of the orchard will have 7
or 8 trees in a row with it, and in other parts it's just one tree."
He said the disease is worrisome because McIntosh are popular regional
varieties.

Trees from dwarf rootstocks grow smaller, it's easier to harvest them
and the smaller size allows trees to be planted closer together.
Michigan and New York are among the top apple producing states.

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Communicated by:
ProMED-mail


[The problem above is reported to be associated with specific dwarfing
rootstocks used for specific apple varieties. This could imply one or
several graft transmissible disease agents such as viruses, viroids,
or phytoplasmas. More than 20 diseases of apple have been shown or are
suspected to be caused by a member of these groups of pathogens, but
molecular methods are needed for reliable diagnosis. Monitoring of
affected orchards would also be important since rate and patterns of
spread can provide clues as to the type of pathogen involved.

Maps
USA:

Michigan:
and

New York state:
and


Pictures
Photos of apple diseases via:

McIntosh apples:

Size of dwarf compared with standard apple trees:


Links
Information and resources for apple diseases:
,
, and

Virus diseases of apple:

List of major pathogens and disease of apple:

McIntosh apple variety:
and

Apple rootstocks:
. -
Mod.DHA]

[see also:
Scab disease, apple - India: (JK) alert 20100430.1397
2009
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Black rot, apple - Germany: northward spread 20090914.3230
Scab disease, apple - Australia: (WA) 20090519.1880
2008
----
Scab disease, apple - India: (HP) 20080829.2706
Marssonina blotch, apple - India: (HP) 20080813.2501
Scab disease, apple - Australia: (WA), eradication 20080514.1621
2007
----
Fireblight, pear, apple, quince - Morocco (Meknes): 1st report 2006
20070321.0990
2006
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Apple proliferation phytoplasma - Germany (Sachsen) 20060217.0524
2005
----
Fruit rot, stored apples - Chile: 1st report 20051202.3473
Necrotic leaf spot, apple - Turkey (Isparta) 20051020.3056
Canker and twig dieback, apple, pear - USA (WA) 20051015.3001
Apple mosaic - Turkey (Anatolia) 20050904.2616
Apple scab, races - Spain 20050819.2433
Apple core rot - India (Himachal Pradesh) 20050808.2313
Apple scab - India (Himachal Pradesh): 1st report 20050612.1645
Fire blight, apple, pear - Slovakia 20050107.0038
Apple sessile leaf phytoplasma - Lithuania 20050104.0012
2004
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Sphaeropsis sp., postharvest rot, apple - USA (WA) 20040217.0515
2003
----
Fire blight, apple, pear - Slovak Republic 20030808.1952
Fireblight, apple, pear - Slovenia 20030729.1863
Marssonina leaf blotch, apple - Italy 20030724.1804
2002
----
Botryosphaeria, apple, first report - Bolivia 20020507.4125
2001
----
Fire blight, apple, pear - Switzerland 20011206.2964
Fire blight, apple, pear - Slovenia 20011205.2946
2000
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Fire blight, apples - USA (Michigan) 20000624.1041
Fire blight, apples - Spain 20000321.0401
1998
----
Apple proliferation phytoplasma - Netherlands 19980706.1265]
........................................dha/mj/jw
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