Treesearch

Dwarfmistletoes (Arceuthobium spp.), considered the most important disease problem in California forests, cause extensive damage to coniferous timber species throughout the West. Reduction of the damage depends on adequate knowledge of the biology and pathology of these parasites. Much needed information is lacking, and many points of dispute remain concerning the behavior of dwarfmistletoes. Information about the parasites on true firs (Abies spp.) is particularly meager, for most studies of dwarfmistletoes have been made on other timber species. Forest disease surveys conducted by the...

Thermal radiation measurements in Project Flambeau fires involved a limited number of conventional radiometers located outside the fire periphery. A simple, cheap, easily-fabricated, light-weight, self-contained, rugged dosimeter was desired to withstand a hot fire environment, including a specific energy input of 5,000 cal cm -2, and to record the fraction of this energy which was absorbed as thermal radiation from the fire. A few meters were assembled frorn materials on hand and placed on towers available within the test site. This paper reports details on the original meter design,...

Hand baiting for rodent control and sowing patch cuttings in December 1965 produced 880 to 2,540 pine seedlings per acre by July 1966. A tractor-drawn drag used to cover seeds in some areas significantly improved germination in one trial. Costs per hundred seedlings per acre for dragged compartments were $1.08 and $1.33; for other compartments: $0.43, $1.14, and $1.88.

Tree hazard control efforts on recreation sites are subject to budget and administrative restrictions. To make the most effective use of available control funds, priorities should be assigned to various classes of tree defects and a budget set up. With the method provided, local priorities are based on cost effectiveness. Some guide lines and a worksheet for planning a local budget are suggested.

A new parallax wedge (range: 1.5 to 2 inches) has been designed for use with large-scaled 70-mm. aerial photographs. The narrow separation of the wedge allows the user to measure small parallax separations that are characteristic of large-scale photographs.

Dry logging slash has been successfully kept dry for later burning by spraying it with asphalt and wax emulsions. The same treatments were tried on green slash. Tests made by applying SS-1 grade asphalt emulsion and a lumber wax on green slash showed that these protective coatings prevented the slash from drying satisfactorily.

Success--defined as oviposition or tree-killing--was obtained by attracting western pine beetles to groups of pines with natural attractants and by en-massed forced attacks on individual trees combined with either physical or biological stress. Preliminary results show considerable agreement with laboratory tests of vapor toxicity.

An estimate was made of the sound wood logging residue remaining after three different experimental cuttings on the Redwood Experimental Forest, north coastal California. The statistics on volume, size, and soundness classes are indicators of what to expect where similar volumes are harvested. The information can be useful to those planning use of logging residues, particularly in developing logging techniques and in deciding on machinery and what to do about initial processing.

In a preliminary study, two chemosterilants-tepa and hempa-were tested for their effects on the fertility of adult bark beetles (Ips confusus [LeConte). Hempa was Ineffective. Tepa proved 97 percent effective in reducing egg hatch, when applied at 10 µg./10 mg. body weight to both parents. The possibility of using a chemosterilant and the male sex pheromone jointly to attract and sexually sterilize insect populations in the field shows promise.