[NAFEX] Not Gummosis on Peaches

Don Yellman don.yellman at webformation.com
Thu Apr 27 10:41:40 EDT 2006


Shirley:

Gummosis is a general classification for fungal diseases that attack the trunk and limbs of peach trees, although bacterial infections (canker) are usually more common on stone fruits.

The little blobs of pectin on your peaches are signs of visits from the oriental fruit moth.  This insect is widespread throughout the eastern U.S., but there are some places, particularly where there are many untended stone fruit trees around, where it is particularly prevalent.  You can minimize the OFM hatch on your own territory with dormant spraying and a rigorous orchard hygiene program, but you can't stop flying insects from coming in from elsewhere.  In my orchard, I have to spray peaches at least four times after petal fall with Imidan to get the little peaches up to the size for final thinning and bagging in ziplock sandwich bags.  If it were not for the ziplocks, I would be spraying chemicals all season long, since the OFM can have 5 generations where I live.  Fungicides like sulphur or serenade have no effect on this insect, and products like Surround would be of only marginal help.  Early damage from plum curculio is also common on peaches, but is not normally t
he problem posed by the OFM.

Growing peaches "organically" in much of the eastern U.S. is almost a contradiction in terms.  The OFM is such an intractable and persistent insect that even a full-blown chemical spray program is barely sufficient in many locations.  I don't like chemicals or spraying either, since it is a lot of work and expense I would rather avoid.  But, being of a practical mindset, I do it because I want ripe peaches at the end of the season.  If it is suspicion of pesticide residues that incline you to strict organic practices, consider that by the end of the season after a few early sprays in April and May, followed by bagging, they are inconsequential.  After a few days on the tree, or a rain, even the insects are unaffected by spray residues, and they are far more sensitive to these targeted chemicals than you or I.

Don Yellman, Great Falls, VA  



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