Posts Tagged ‘sun’

On to Apples

Our troubles are not limited to peaches.  The baby apple has 3 immature green apples on it, and one of them has suddenly developed a big brown spot!

Can’t be cavalier about this, after what happened to the peach tree!  So, we picked the little apple and determined to figure out what ails it.

The spot is just a basic brown spot, about the size of a nickel (the entire apple is smaller than a little lime).

It’s never easy!  Here are two pictures from different websites (both from institutions of higher education) showing brown spots on green apples.  Our apple looks like both of these.  So we must decide which it is.

Black rot (photo credit:  nysaes.cornell.edu)

Sun scald (photo credit:  science.oregonstate.edu)

One (at least, this one) is inclined to decide this is sun scald (or sunburn) because that’s a simple problem, not something that other trees can “catch.”  Not pathogenic, something people can relate to without going “ick, germs.”

But actually, I think sun scald is the most likely for a real reason:  black rot is mostly a problem in warm, humid areas of the southern U.S. (our area, in the Central Valley of California, is certainly warm, but also very dry), and is accompanied by a characteristic “frog-eye” pattern of leaf damage, which I don’t see.  Sun scald (or sunburn) is a problem that can occur anywhere geographically, when it’s hot out with clear skies.  This describes our place most of the summer.  The fruit on the southwest side of the tree is most often affected (although these trees are skinny babies and thus talking about side of the tree is kind of silly, it was indeed the most southwestern of our 3 apples that got the spot). And light-skinned varieties, like this one, are most frequently the victims.

Apple sunburn occurs most frequently when you have gone from a few days of cloudy weather to a sudden clear and hot spell.  We did have some clouds a week or so ago, so maybe…

Best way to control this, I am finding from the printed sources I’ve located, is to prune the tree correctly so it grows into a configuration that naturally shades the fruit from the sun.  More reason to learn how to prune well!

Dan

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