North American Fruit Explorers mailing list at ibiblio

[Nathan Torgerson <nathantorgerson@yahoo.com>]

Looking at my Zestar tree, I noticed yellowing leaves with brown spots on 5% of the tree. This took place in about 24 hours. 

Picture: http://www.nafex.org/uploads/is%20this%20necrotic%20leaf%20blotch%20on%20zestar%20apple.jpg 55K...next time I'll use underscores to eliminate the "%20" between each word...sorry about that.

 

It appears to fit the description of nectrotic leaf blotch, as the Twin Cities had one cool overcast week in the 60's followed by 3 hot and humid days (90+ degrees) over the Memorial Day Weekend. I'm not sure if Zestar is a Golden Delicious relative (Official cross is State Fair x MN 1691), which seems to be a prereq for this type of leaf blotch .  Anyone else seen this on Zestars?

 

I'm tempted to just leave the tree alone...I have never sprayed my trees for anything and really don't want to start if possible.  Has anyone dealt with this problem before? Will I lose my crop/tree if I ignore it?

 

Thanks,

Nate Torgerson

Andover, MN zone 4a

 

Description courtesy of Tennessee Extension services (there is also a picture on the site):

http://web.utk.edu/~extepp/fpn/fpn061504.htm

 

Necrotic leaf blotch is actually not a disease, but a physiological disorder. It occurs on Golden Delicious and its sports. The affliction often occurs in waves during the summer. It tends to be more severe when hot, sunny weather follows several days of mild, cloudy weather. Large, irregular-shaped, necrotic (brown) spots appear suddenly on green leaves. Most affected leaves soon turn yellow and fall from the tree. Defoliation can be significant. Although necrotic leaf blotch is not caused by a fungus, severity is decreased by a regular fungicide program.

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