On Monday I had the pleasure of participating as an instructor in a fruit tree-pruning seminar sponsored by the California Arborists Association. A non-profit organization of professional arborists, CAA promotes training, education, and high professional standards of practice in tree care. The fruit tree-pruning seminar was one of many workshops and events on their calendar for 2007.

On what turned out to be a very rainy day, the seminar was held at the historical John Muir House Estate in Martinez. The group of about 40 arborists in attendance included tree service owners, tree workers and two registered consulting arborists. (Yours truly and Ray Morneau, president elect of the Western Chapter of the International Society of Arboriculture.)

In the morning, lead speaker Phil Evans of San Francisco State University Grounds Dept. gave the group an introduction to fruit tree pruning concepts and how they apply to the various kinds of fruit trees grown around the Bay Area, along with some helpful handouts for us to take home. (One in particular may be of interest and available to homeowners through UC Cooperative Extension: “Pruning Fruit Trees,” University of California Leaflet 21171).

In the early afternoon, Brian McGovern, a woodpecker certified arborist from San Jose, shared his experience and advice on the practical side of pruning fruit trees as a business. While many tree care professionals have found that fruit-tree pruning tends to be a money-losing practice, McGovern has successfully combined good pruning practices with good client relationships for a profitable business. For me, his strongest take-home point was about listening and responding to the client.

As the rain continued to pour, my time arrived to lead a group of arborists through the fruit tree groves, in search of trees to prune. In rain gear and mud-caked boots, lugging our pruning tools, we took a close look at a number of the fruit and nut trees, young and old, scattered around the old Muir Estate. Making the best of it in the wet conditions and the awkward light of a rainy day, we did a little pruning and a lot of talking about tree care. It was fun to share some knowledge and experience and to see the enthusiasm and curiosity in the group.

Without going into the details for specific tree varieties, here are some of the stronger points made in the seminar, which apply to fruit trees in general.

• Read the tree. When preparing to prune a tree evaluate the overall vitality and structure. (Ironically, one of the big old apple trees one leader used as an example of spur production and pruning options turned out to be dead!) There are clues in the growth increments — shoot length from previous years of growth - root collar, branch angles, and branch distribution that can help you decide what to do, including the removal of a dead or dying tree.

• Think into the future. Young trees need to generate branch structure, even while they are producing their first crops of fruit. Imagine the future branches of your young tree growing into the space around and above it, and guide it there by thoughtful pruning. Older trees need to replace aging, unproductive fruiting branches without interrupting fruit production. Select and retain inner, lower, small branches for development as fruiting branches in the future, and be prepared to remove older branches and fruiting spurs when they decline.

• Sanitation pays off. Tree diseases have less opportunity to spread when diseased stems and fruits are removed promptly. This includes removing them from the tree and from the ground under the canopy. Pruning tools can spread disease. Sanitize them regularly with Lysol, a bleach solution or rubbing alcohol, especially while working in a heavily diseased tree.

• Beauty and fruit production can go together. Some of the commercial agricultural fruit tree-pruning practices are very severe and unsightly. Fruit trees in the landscape can be pruned for appealing structure and still produce copious fruit.

And here are a few of the more specific tips shared by the speakers:

• Water sprouts — vigorous vertical inner branches— tend to grow back when removed during the dormant season. Instead, let them leaf out, and then remove them in spring.

• To improve structure, use string to pull small branches into desired positions. Leave the string in place for only one year.

• Use the “broomstick rule” in deciding the future height of your fruit tree. If you can’t reach it with a broomstick, you probably won’t pick the fruit.

• Consider saving a favorite old heirloom variety tree by planting a new tree of the same species near it and then budding or grafting the old tree on to the young tree.

• Summer pruning can be effective in controlling tree size, but don’t over-prune. Retain about a dozen leaves on the stem above a desirable piece of fruit to provide it with sugars.

• Do not allow your fruit trees to become drought stressed in spring while fruit is setting and expanding to its mature size.

Bill Pramuk is an ASCA registered consulting arborist. Please send questions to bpramuk@pacbell.net)