Joan Swenson: Fruit trees won't live forever
| Tuesday, Aug 12 2008 02:14 PM
Last Updated Friday, Mar 27 2009 06:08 PM
A couple of years ago I was set to remove our Flavor Queen pluot because one large scaffold had died and throughout the tree it looked as if large branches had sprung leaks from which large, slow-moving flows of thick brown sap oozed.
I had begun considering a new tree to replace the old workhorse. The tree looked unwell, but my husband, who loves his trees dearly, wanted to keep it.
But the time has come and later this year, the Flavor Queen pluot that has given us at least 10 years of sweet, golden-green plum-apricots, will be cut down.
We’ve got borers, possibly prune limb or American plum borers, from what I’ve read and pictures I’ve seen of trees with similar damage. These borers leave holes, reddish orange frass (sawdust), and pockets of gum as the tree tries to drown the attacking borers.
Interestingly, borers don’t live permanently in fruit trees. The holes in the bark of the tree are exit holes as the adult borers chewed their way out of my poor pluot and flew off. For the borers to return to lay eggs again, conditions would have to be favorable for the pests.
The best way to keep deciduous fruit trees healthy is by keeping them watered. The larger the tree, the more water it will need. Perhaps in the hottest part of summer we let the tree become water-stressed and that attracted the opportunistic borers.
We might have tried treating for the borers beginning when we first noticed the frass and gum, but did not. In fact, dormant sprays applied during the winter are fairly ineffective against borers. And systemic insecticides will not work because they are carried in the xylem — the transporter of water up through the tree — and borers feed in the phloem, where the sugars are.
So we lived with the damage until it was too much. We kept the tree watered and we fertilized. My husband loved this tree and its fruit, so I had it pruned to remove the worst damage and it limped along for a couple of more seasons.
But we had only a few of the delicious pluots this summer.
Here’s the thing: deciduous fruit trees won’t live forever. In fact, most survive in our area for about 15 years and then begin declining. Peaches are going to have a shorter life span than, say, my monstrously healthy apricot tree.
My pluot is checking out about on schedule. We will miss it, even so.
MASTER GARDENER
John Karlik’s Master Gardener I and IV classes begin soon.
Hundreds of people have taken Karlik’s classes since he began teaching them in 1985. The University of California Cooperative Extension horticulture adviser teaches gardening skills using a scientific viewpoint as well as a sense of humor and offers practical, pragmatic tips on gardening that can save money and resources.
Master Gardener I will be offered from 5:30 to 8:30 p.m. Tuesdays beginning Aug. 26. The class runs 16 weeks.
Topics will include soil science, plant design, landscape design principles, and pest management with an emphasis on integrated pest management. Sessions on vegetable crops, deciduous fruits and citrus will be part of the course.
Master Gardener IV meets from 5:30 to 8:30 p.m. Thursdays beginning Aug. 28. It is also a 16-week class. Topics from previous MG classes will be expanded upon as will landscape design and subjects relating to the environment.
Both classes will meet at the UC office, 1031 S. Mount Vernon Ave. Registration for each class is $70. Call the extension office at 868-6200 to reserve a spot in the class or contact Karlik at jfkarlik@ucdavis.edu. Registration will be handled the first night of each class.
