I am now not so concerned with the aphids that had formerly inhabited my residence but find myself wondering what unseen predator lurking in my home has devoured the aphids and may now be considering a more substantial alternative prey! Coming this fall to a theater near you!

Integrated pest management, commonly called IPM, is very old technology that exploits natural ecological processes. I first learned about it in Mrs. Bricker's first-grade class at Bucknall School in the Saratoga/San Jose area. It was about 1973 or '74, and ecology was all the rage. We didn't exactly study IPM but learned about how ecology works. The oak tree (I believe it was a valley oak, Quercus lobata) produces acorns that are eaten by squirrels, who are eaten by hawks, etc. Any disruption to this process affects everyone involved. For example, removal of the oaks would theoretically diminish the population of squirrels and subsequently diminish the population of hawks. However, in the Santa Clara Valley squirrels proliferated among the fruit orchards but hawks lacked nesting sites. The valley was consequently overrun with squirrels. Where is Evilkat when you need him?

I have obtained some of the most comprehensive yet simple explanations of basic IPM from the West Valley Clean Water Program. I found information concerning natural management of pests in the garden, control of aphids, control of snails and slugs, safe use and disposal of pesticides and ecologically correct lawn management. I would certainly like to discuss these topics in more detail, but until then, more information may be obtained directly from the West Valley Clean Water Program by calling 408.354.5385.


Tree of the Week: Silk tree

To be blunt, the silk tree, Albiz(z)ia julibrissin, has a few problems. I have never been the sort of horticulturist to discuss only the pretty flowery qualities of any subject so will first explain what I don't like about it.

Silk tree, also known as mimosa, is somewhat messy. After the floral litter stops falling in late summer and autumn, the foliar litter begins to fall. The finely textured, bipinnately compound leaves disintegrate into individual leaflets that are too small to rake. ("Bipinnately compound" leaves are divided into leaflets arranged on a central rachis. These leaflets are likewise divided into secondary leaflets in a similar pattern.) When the foliage is gone, seedpods continue to fall. It may be best to allow the mess to accumulate and obscure fractures and undulations of any adjacent concrete displaced by the potentially voracious root systems.

Silk tree is otherwise an absolutely fabulous tree. In fact, it is my sister's favorite species of tree and my grandmother brought one from Oklahoma for her garden in Santa Clara—as if there are not already too many here. Although the roots can be shallow and distended if irrigation is too frequent and soil is dense, good drainage and infrequent but generous irrigation promotes development of deeper and complaisant root systems that might never been noticed at the surface. Regular irrigation is preferred, but minimal irrigation is tolerable.

A silk tree can grow rapidly to 30 feet high and even broader but is usually smaller. The shade provided is not as "dark" as that of other shade trees. The profusion of fluffy pink flowers over the flat-topped canopy is impressive if it can be seen from upper floors or higher areas of the garden. Standard specimens are supported by single trunks and require less space below the canopy, but multi-stemmed specimens display the appealing limb structure.

Horticulturist Tony Tomeo can be contacted at 408-358-2574 or at LGHORTICULTURE@aol.com.