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Attacks by the oak ambrosia beetle (Monothrum scutellare) accelerated and increased the amount of wood decay in stems of downed coast live oak (Quercus agrifolia) trees. When permethrin insecticide was sprayed on oak bark surface, the ambrosia beetles produced only one-fourth as many galleries in the sapwood as compared to sapwood beneath the unsprayed bark surface. Although decay fungi initiated infection in oak in the absence of beetles, the amount of wood decay was much greater in trees with beetle activity. The ambrosia beetles deeply penetrated the sapwood and constructed extensive galleries that hastened wood decay by decay pathogens. The insecticide inhibited beetle attack and formation of egg galleries and greatly decreased the amount of wood decay.

We tested the efficacy of tree-shelters on selected container-grown trees in the nursery and on redwood seedlings transplanted into the landscape. Treeshelters accelerated shoot growth of southern magnolia, holly oak and deodar cedar, but root growth was reduced during the first growing season as compared to the controls. Sufficient shoot-root development of the trees was achieved only after two growing seasons. One-year-old redwood seedlings successfully established themselves whether grown in treeshelters or not, while receiving 1/7 to 1/14 as much water as they would in a nursery bed grown in one-gallon containers. The seedlings in treeshelters grew significantly taller.

Author(s): Hickman, Gary W; Svihra, Pavel | Abstract: Learn the basics of planting and caring for a new landscape tree.

Bud break, not a calendar date, is the best time to protect sycamore trees against the sycamore scale, Stomacoccus platani, with insecticidal sprays. It is at bud break that the highest density of crawlers appears on twigs.

Treeshelters were used for the nursery production of Cedrus deodara Loud. (deodar cedar), Quercus ilex L. (holly oak), and Magnolia grandiflora L. (southern magnolia) trees growing in 19-liter containers. Air temperature, relative humidity, and CO, concentration were higher inside the treeshelters than outside. Trees grown inside treeshelters were 74% to 174% taller than trees grown without shelters. Trunk caliper of Magnolia and Quercus was not affected, however, for Cedrus trees caliper was larger for trees grown without a shelter. Upon removal of the shelter, Cedrus trees were incapable of supporting their own weight. Lateral branch development was inhibited and leaf senescence was greater with Magnolia trees grown in a shelter. Quercus trees grown in shelters were ready to be transplanted into the landscape. Water use was similar for trees grown with or without shelters. Trees grown in shelters had lower root fresh weights.

Treeshelters are translucent, polypropylene tubes that have been used in England for 10 years to improve the transplantation success and early growth of trees in the landscape. The focus of the presented research will be on the use of treeshelters in producing plants in the container nursery. The results from outdoor nursery and greenhouse, solution culture experiments will be presented. Treeshelters increase the temperature, relative humidity, and carbon dioxide concentration around those plants growing in them. Photosynthetically active radiation (PAR) inside shelters is reduced 40-60% depending on treeshelter color. Plants growing in treeshelters show increases in height and in the ratio between total fresh weight and total dry weight. However, plants growing in treeshelters also show decreases in leaf, stem, and root fresh and dry weights and leaf area. The potential benefits and current challenges surrounding the use of treeshelters will be discussed.