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FALL PRUNING MAY NOT BE THE BEST

In the past, this gardener has always maintained that it did not matter what time of year limbs are pruned from trees. At a recent meeting of the Western New York Nursery and Landscape Association, Cornell University's George Hudler indicated that this may not quite be true.

Before someone goes screaming out of his house to stop his arborist from pruning a tree, I must emphasize that the difference in pruning time is very slight and may not be at all. In fact, Hudler said he had no proof of the following, but it made possible sense to him.

It must also be emphasized that the type of pruning discussed here is the removal of entire limbs to thin the crown or raise the height on trees. This does not include the type of pruning that tips branches for the purpose of shaping evergreens. This discussion is limited to the entire removal of unnecessary branches.

Trees wall off or defend against pruning wounds (or any wound) by putting up a barrier to stop decay fungi from entering. This defense happens as a result of chemicals in the tree accumulating at the site of a wound almost instantly.

Or at least they do this when they are not dormant. During the dormant season, however, these walls of chemicals do not form, or at least they do not form very quickly. On the other hand, decay and pathogen fungi can be active any time the temperature is above 32 degrees.

It would seem, then, that October, November, December and January could be the worst months to prune. Saps and resins make this point moot on conifers, because they plug the pruning wounds quite effectively themselves.

Still, a little orange shellac to seal the wounds may help on hardwoods. Remember, these "sealants" are only temporary; they only have to get the tree into late winter. It has been proved in the past that pruning paints are effective only temporarily, if at all.

Before I am hit with an avalanche of disbelief from my friends the arborists, I must say again that the chances of these fungi problems occurring are very slight. And besides, there are plenty of good reasons to prune when the trees have no leaves.

Dormant pruning allows the skeleton of the tree to be seen easily, and individual branches can be traced to their source, which allows removal of competing branches. When the trees are full of leaves, it's often difficult to do so. There is just too much material in the way.

And to be honest, much pruning and removal work is scheduled by tree services during the winter, when other demands on their time (spraying, fertilizing, etc.) cannot possibly be completed. In many cases it's better to get the pruning work done when time permits rather than waiting until time is short and the job never happens.

Moving raspberries

Q -- We have some raspberries in a location that is probably a bit too shady. They have not produced much in the way of fruit, and we would like to move them. When can we do so?

-- T.K., Colden
A -- Raspberries will grow OK in the shade, but they will not produce well. They need full sun if gardeners are expecting them to fruit well.

The best time to move them is in April. Fall would probably be OK, if they are mulched well after moving, but my choice would still be spring. Fruit production will be low or not at all the first year, but by the second season they should begin to show some results.

For answers to your gardening questions, send a self-addressed, stamped envelope to Ken Brown, in care of the Features Department, Buffalo News, P.O. Box 100, Buffalo, N.Y. 14240. Brown is a horticultural consultant specializing in integrated pest management.

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