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Sudden oak death, caused byPhytophthora ramorum, is widely established in mesic forests of coastal central and northern California. In 2000, we placed 18 plots in two Marin County sites to monitor dis- ease progression in coast live oaks (Quercus agrifolia), California black oaks (Q. kelloggii), and tanoaks (Lithocarpus densiflorus), the species that are most consistently killed by the pathogen in these areas. Through early 2008, the numbers of newly infected trees increased for all species. The infection rate for trees that were asymptomatic in 2000 was 5.0%y "1 for coast live oaks, 4.1%y "1 for black oaks and

Sudden oak death, caused by Phytophthora ramorum (Werres, de Cock & Man in’t Veld), has killed thousands of oaks (Quercus spp.) in coastal California forests since the mid-1990s. Bark and ambrosia beetles that normally colonize dead or severely weakened trees selectively tunnel into the bleeding cankers that are the first visible symptoms to appear on infected coast live oaks, Q. agrifolia (Nee). The role of these beetles is of interest because once beetles attacked infected trees, median survival was found to decline, from seven to less than three years (McPherson and others 2005). Beetle attacks consistently precede the emergence of sporophores of Hypoxylon thouarsianum (Leveille) Lloyd, a decay fungus that structurally weakens infected trees. The dense clusters of ambrosia beetle tunnels can extend greater than 15 cm into the sapwood, impairing water conduction and potentially introducing opportunistic organisms. This research has three principal goals: 1. Quantify beetle responses to P. ramorum-infected coast live oaks; 2. Identify the factors that influence beetle attacks on these trees; 3. Evaluate the short and long term effects of beetles on colonized trees. This study was conducted in protected land of the Marin County Open Space District. In July 2002, we mechanically inoculated 80 mature coast live oaks with P. ramorum and wounded another 40 without inoculation as controls for beetle responses to wounds. To prevent beetle attacks on trees, we sprayed half of each group to a height of 2.5 m with permethrin, an insecticide with relatively low toxicity to non-target organisms. Insecticide was applied following inoculation, then twice per year, in February and August, prior to the principal beetle flights. Sticky traps were hung on the insecticide-treated trees to monitor insect landing and beetles were collected from these traps periodically through 2003. Eighty percent of inoculated trees developed bleeding symptoms. Within 18 months after inoculation, trees exhibited the sequence of symptom progression observed in natural forest infections: bleeding, bleeding plus beetle attacks; and bleeding plus beetle attacks plus emergence of H. thouarsianum sporophores. Canker size, defined by bleeding surface area, had a mean value of 0.19 m 2 (standard error = 0.03), with a range from 0.008 m 2 to 1.13 m 2

Sudden oak death (SOD), caused by Phytophthora ramorum, is killing oaks and tanoaks in the Coast Ranges of California, from Monterey County to Humboldt County. In March 2000, 20 disease progression plots were established in Marin County, California, to characterize the progress of disease symptoms, and to determine the fidelity of the association of three or more bark and ambrosia beetle species (Coleoptera: Scolytidae) with diseased oaks and tanoaks. Symptoms of sudden oak death and signs of associated organisms were recorded from coast live oaks (Quercus agrifolia), California black oaks (Q. kelloggii), valley oaks (Q. lobata), and tanoaks (Lithocarpus densiflorus), four times per year, from March 2000 through March 2003. Symptoms and signs in Q. agrifolia progressed from bleeding, to infestation by scolytid beetles, to the development of fruiting structures of the fungus Hypoxylon thouarsianum. Mortality of symptomatic trees increased from 2000 to 2003 as follows: Q. agrifolia (n = 668), 5.8‐17.4%; Q. kelloggii (n = 53), 3.8‐9.4%; and L. densiflorus (n = 164), 8.3‐22.2%. All 31 Q. lobata remained asymptomatic. From 2000 to 2003, bleeding trees were 25.0‐23.6% of living Q. agrifolia, 15.5‐25.0% of Q. kelloggii, and 39.0‐62.4% of L. densiflorus. Scolytid beetles colonized more than 95% of the living symptomatic Q. agrifolia that subsequently died. Same-symptom cohorts were followed from March 2000 through March 2003. In the asymptomatic Q. agrifolia cohort, 12.0% developed bleeding by 2003. For the bleeding only cohort, 22.7% of Q. agrifolia died, but 73.5% of the beetle-colonized bleeding cohort died. Bleeding developed in 40.9% of the initially asymptomatic L. densiflorus cohort. By 2003, 24.6% of the initially bleeding L. densiflorus cohort had died. Both Weibull and Cox Proportional Hazards regression were

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.

“Sudden oak death” refers to a complex set of symptoms that has already culminated in the death of tens of thousands of California oak trees. Now confirmed in seven coastal counties, SOD attacks California tanoak, coast live oak and California black oak. Although several fungal species and the western oak bark beetle and ambrosia beetles have been associated with the syndrome, we now have solid evidence that a newly discovered Phytophthora species is the primary causal agent. This Phytophthora species was recently isolated in rhododendron as well; it may be the same species that was isolated, but not described, on rhododendrons in Germany in 1993. The discovery of SOD on rhododendron has serious implications. The disease may well be present at the ecosystem scale, and its appearance on an ornamental plant suggests the possibility of wider dissemination. A team of UC scientists has developed an integrated approach to managing this disease, including practices to enhance tree health. Early disease detection and targeted chemical treatment may also hold some promise for disease management. In addition, we have developed a molecular probe that will enable rapid identification of SOD from any infected part of the plant. Ultimately, the fate of the oak species affected by SOD will be determined by the levels of disease resistance present in natural populations of these trees.

Treeshelters (Tubex® polypropylene tubes, 4 inch diameter, 4 ft tall) inhibited development of redwood tree (Sequoia sempervirens) roots. Unprotected redwood trees without treeshelters gained more root fresh and dry weight. Trees grown in treeshelters produced roots with smaller diameter. These data suggest that the treeshelter environment might temporarily prevent redwood trees from attaining optimal root development and anchorage. Redwood seedlings are not suitable candidates for establishment in treeshelters.

Excision of infected or infested branches from woody plants was recommended as a control tactic more than 150 years ago. The term "eradicative pruning" was first introduced for Dutch elm disease control. Eradicative pruning can eliminate local and regional branch (limb) infection or infestation to prevent further spread of a pathogen or pest in the tree. When combined with other chemical and cultural treatments, eradicative pruning fits well to the concept of Integrated Pest Management (IPM) or Plant Health Care (PHC). Timing of pruning, severity and extent of symptoms, location of pathogen or pest attack, stage of infection or infestation, and contamination of pruning tools all influence the success of eradicative pruning. This report presents a guide for selected disease and pest attacks that can be successfully eradicated from woody plants in California.

Flight of a flatheaded borer (Agrilus burkei) begins in late March or the beginning of April and lasts for 35 to 62 days. After emergence through D-shaped holes in the bark, the adults feed for one week on the foliage; they live about 12 days. The first egg mass is oviposited 7 days after emergence. Hatched larvae penetrate the bark surface directly into the phloem tissues. The larval stage lasts from April to February of the next year. In March a pupa is formed beneath the bark and the new imago emerges. The apparent propensity of A. burkei to attack poorly growing alder trees suggests that white alders, Alnus rhombifolia, should be planted only in landscapes where moisture stress can be avoided or minimized.

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.

As the pressure of people wishing to live in urban forests continues to grow, the fire problem becomes more serious for these residents. The most recent firestorm in the densely populated Oakland-Berkeley Hills in the San Francisco Bay Area killed 25 people and destroyed 3,011 houses. Damage is currently estimated at $1.5 billion. Vegetation management is an important factor for fire speed control and a structure's survival. Effective silvicultural and arboricultural practices can change fire hazardous landscapes into safer ones in which flame intensity can be controlled by firefighters and residents have a chance to escape.

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.

When five sycamore cultivars (Bloodgood, Columbia, Liberty, Yarwood, and Saratoga 86-336-C), grown in 5 gallon containers, were exposed to natural infection by the sycamore anthracnose fungus, Apiognomonia platani, Bloodgood was significantly less affected than Columbia, Yarwood and Liberty. Saratoga 86-336-C was highly susceptible. In contrast, Bloodgood was highly suscepitible to powdery mildew, Microsphaeria penicillata, while Yarwood displayed the highest degree of resistance to the disease.

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.

Scolytus multistriatus attack density, gallery length, and brood production beneath the bark of Ulmus procera branches 2 to 6 cm in diameter increased as branch diameter increased. Beetles did not complete development in 2-cm-diameter branches, and an average of 70 beetles per dm2 emerged from 6-cm-diameter branches. Removal of small-diameter, moribund branches above 2 cm in diameter may be necessary if all potential breeding sites are to be eliminated in Dutch elm disease prevention programs.

Catches ofDendroctonus frontalis andIps avulsus on traps surrounding bolts infested with both sexes of each species in the gallery were not significantly different from catches at bolts infested only with the sex which normally pioneers the host colonization process. In contrast, the presence of the second sex in the gallery significantly reduced catches ofI. grandicollis andI. calligraphus and, additionally, the presence of females in the male galleries ofI. calligraphus significantly reduced the catch ofI. avulsus females as compared with their response to bolts infested with the maleI. calligraphus only.

Six mil clear polyethylene sheeting, resistant to ultraviolet rays, was used as a seal to prevent the colonization of elm firewood by Scolytus multistrlatus, the vector of the Dutch elm disease fungus. In California, elm firewood sealed and aged under polyethylene sheeting for up to three months maintained a similar attractiveness to the bark beetle as did freshly cut firewood, after wood was exposed. When wood was aged for four to six months under sheeting and then exposed, the beetles, not only delayed their attacks but also colonized fewer bolts, and in lower densities, than on freshly cut bolts. When firewood was sealed and aged for seven or more months under sheeting before exposure, it was no longer attractive to S. multistriatus.

Scolytus multistriatus (Marsham) was significantly more attracted to bolts freshly cut from Ulmus procera Salisb., than to U. pumila L. and U. parvifolia Jacq. and unbaited controls in a pure stand of U. procera . Beetle attraction to U. parvifolia was significantly lower than to U. procera and U. pumila and did not differ from that of unbaited controls. In contrast, the response of beetles to bolts of U. procera and U. pumila was not significantly different in a pure stand of U. pumila .

The smaller European elm bark beetle, Scolytus multistriatus, vector of the Dutch elm disease fungus, is attracted to pruned limbs of European and Siberian elm compared to healthy, non-pruned limbs. To minimize the spread of Dutch elm disease it is suggested that pruning of elm limbs be undertaken during the fall and winter when bark beetle activity is reduced or absent.