University of California Pine Study

The purpose of this study was to observe the performance of several exotic pine species and one hybrid. Also, two lots each of Pinus halepensis, brutia, and eldarica were compared for habits of growth, form, and color. Insect activity became an item of major concern and was therefore noted.

The planting was made at the University of California Deciduous Fruit Field Station (DFS), San Jose, in April 1971. It was maintained under the supervision of Tom Kretchum, Superintendent of the Station. The plants had been grown from seed and transplanted into one gallon cans at U.C. Davis.

Prior to planting, the level and deep loam soil was disced, irrigated, and furrowed. The planting was made on the ridges and the furrow were irrigated as needed. No fertilizer was added at any time. Weed oil was used for weed control. The planting started with eight plants per lot and was thinned to half that number in 1975. The plants were rated for injury following the December 1972 freeze and for their recovery eight months later in August. There were no observed effects on the pines at either time. Here are summaries on habit and growth rates:

Pinus rigida Mill. Prostrate the first three years. Became erect in the fourth year and is an attractive single trunk, short needle pine.

Pinus pinaster Ait. Slow growing the first two years after planting; quadrupled in height in the third season; has spreading branches and appears well adapted (healthy, vigorous). Very distinctive tree with red buds and very long and coarse needles.

Pinus nigra Arnold. Slow growing the first three seasons, but doubled its growth in the fourth. Its width nearly equals its height.

Pinus resinosa Ait. Died of unknown causes in the first year.

Pinus jeffreyi X coulteri hybrid. Grew slowly the first three seasons; has long grey-green needles with a P. jeffreyi form.

Pinus halepensis Mill. The two lots did not noticeably differ in form or appearance and were typically P. halepensis. They grew rapidly after the second season.

Pinus brutius Ten. Lot. 69.784 grew in height and appearance very similarly to P. eldarica; grew slowly the first two seasons, then rapidly. Lot 69.372 was a typical P. halepensis.

Pinus eldarica Medwed. Both lots appeared similar in all respects; blue-dark green needle color and a compact habit of growth; ideal for Christmas tree use. They grew more rapidly after the first year than P. halepensis and P. brutia in this study. In comparison with P. halepensis, P. eldarica appears similar except for the darker green needle color and the more compact less rangy habit of growth. P. eldarica appears to be more sensitive to Sequoia pitch moth than P. halepensis.

• © 1979, International Society of Arboriculture. All rights reserved.