[Apple-Crop] Elsinoe fruit and leaf spot on apples

[Two Onion Farm]

Hello,

We have had quite severe problems in the last two years with Elsinoe 
fruit and leaf spot on several of our apple varieties.  I am curious 
whether growers or researchers on this list have had any experience with 
Elsinoe or success controlling it.

We have an organic orchard of scab-resistant varieties in southwest 
Wisconsin.  Elsinoe causes causes occasional minor leaf symptoms on most 
varieties.  A few susceptible varieties (Scarlet O Hara, Pixie Crunch, 
CrimsonCrisp, Sundance) develop widespread foliar infection during 
summer, followed by late summer defoliation which can be quite severe on 
some trees.  Pixie Crunch and Sundance also suffer severe fruit symptoms 
which develop and progress rapidly starting in mid-late August.  On 
these two varieties we've had almost no fruit in the last two years 
which are suitable for fresh market.  Other varieties will rarely have 
an occasional fruit lesion.  Fruit symptoms do not seem to significantly 
affect flavor and do not progress in cold storage after harvest which is 
good.   Early tree defoliation does appear to reduce fruit flavor and 
delay ripening, as well as I presume reducing general tree health.

Some other varieties which we grow which do not suffer severely are: 
Pristine, Priscilla, Redfree, Williams Pride, Sir Prize, Liberty, 
Priscilla, Goldrush, Enterprise, CrimsonGold, Akane, Galarina, Winecrisp.

Not much to read about Elsinoe on the internet but it has been reported 
to be quite severe in some organic European orchards of scab resistant 
varieties including Crimson Topaz and Prima.  I only know about it 
because the Univ. of Wisconsin plant disease diagnostic clinic 
identified it on our fruit.  I have attached pictures of our 
infections.  I've heard from an extension agent in MN that it is quite 
severe in some organic orchards there, where Honeycrisp is mildly 
susceptible and Sweet 16 is highly susceptible

In the last two years when this problem has occurred we have done 
regular sprays of Cueva (sometimes with double nickel) through early 
fall, which seems pretty effective at controlling summer fungal diseases 
and perhaps rusts as well, but not Elsinoe.

I welcome any thoughts or input.

Chris

-- 

Chris & Juli McGuire
Two Onion Farm
www.twoonionfarm.com <http://www.twoonionfarm.com/>
19638 Cottage Inn Road
Belmont, WI 53510
(608) 762-5335 (office)
(608) 726-2550 (cell)
farmer at twoonionfarm.com <mailto:farmer at twoonionfarm.com>

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