When this is on a Golden Delicious at this time of year after a summer like this, it’s likely that it’s necrotic leaf blotch. No pathogen has been associated with it, so we blame it on bad horticulture and call it a “physiological disorder”. It’s interesting that zinc and ziram applied in the summer will reduce the problem.
https://articles.extension.org/pages/60614/golden-delicious-necrotic-leaf-blotch-in-apple-trees This is one of a few problems that were relatively common in the Southeast and Mid-Atlantic, but that we didn’t see in New England until recently. We’ve also seen more black rot, bitter rot, and Marssonina leaf blotch. These are all fungal diseases, and I think they and NLB are all related to warmer night temperatures. I also think that we have seen the build-up of inoculum for the fungal problems over the past few seasons, and that it will more important to sanitation, copper and summer fungicides to keep them from building up to more significant levels. Marssonina leaf spot has been a growing problem, and it could be that. We identified last year and this year in a few orchards, and it has been found in eastern NY. Here’s an article from Srdjan Asimovic at the Hudson Valley Lab. https://blogs.cornell.edu/acimoviclab/2018/09/24/marssonina-leaf-blotch-causes-apple-leaf-defoliation-where-cover-sprays-were-stretched-in-summer-2018/ We’ve had a lot of bitter rot and black rot on fruit. Theser are Glomerella leaf spot and frogeye leafspot, respectively, on leaves. From Dave Rosenberger a few years ago, GLS: https://blogs.cornell.edu/fruit/2012/08/31/glomerella-leaf-spot-a-new-disease-affecting-golden-delicious-apples-in-ny/ If you want to nail it down, you need to submit samples to a pathology lab. Dan > On Oct 9, 2018, at 12:35 PM, maurice tougas <appleman.maur...@gmail.com> > wrote: > > Yup seeing same here. No captan or phosphorous . Goldens but I don't recall > seeing on Jonagold. Ill check. > > Mo Tougas > > On Tue, Oct 9, 2018 at 12:26 PM David Kollas <kollasorchar...@gmail.com > <mailto:kollasorchar...@gmail.com>> wrote: > The photo below, taken yesterday in my orchard, shows a Jonagold tree > among other Jonagold trees that > are dropping leaves. Severity varies from few to many leaves showing the > spots and leaf-drop on different trees. > Similar, but less severe symptoms appear in other varieties that have yellow > delicious in their heritage. I suspect > it to be a fungal infection, because the spots appear on green leaves, which > then turn yellow and drop. Frequent > captan plus phosphorous acid sprays have been applied for sooty blotch in > recent weeks because of frequent rains > and and infrequent appearances of the sun. > > I have seen similar, but less severe occurrences of the disorder in > other years, but would like to hear whether > others are seeing it this year, or have knowledge of the causes and > prevention. > > David Kollas > Kollas Orchard > Connecticut, USA > > > _______________________________________________ > apple-crop mailing list > email@example.com <mailto:firstname.lastname@example.org> > http://virtualorchard.net/mailman/listinfo/apple-crop > <http://virtualorchard.net/mailman/listinfo/apple-crop> > > > -- > Maurice Tougas > Tougas Family Farm > Northborough,MA 01532 > 508-450-0844 > <IMG_1030.JPG><IMG_1030.JPG>_______________________________________________ > apple-crop mailing list > email@example.com > http://virtualorchard.net/mailman/listinfo/apple-crop
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