Hendersonia acicola on pine needles infected by Lophodermella sulcigena

Hendersonia acicola normally infects only needles already infected, in July-August of their first year, by Lophodermella sulcigena. Secondary infection, by H. acicola, occurs at the base of the L. sulcigena lesion either in August-October of the first year (early secondary infection) or after fruiting of L. sulcigena in June-July of the second year (late secondary infection). Early secondary infection prevents fruiting of L. sulcigena. An intercellular matrix forms at the base of the L. sulcigena lesion in response to both early and late secondary infection and rapid tissue disorganisation and disintegration ensues. Secondary infection decreases with increase in height up the tree and often results in needle breakage.     

Histopathology of longleaf pine needles infected by Ploioderma hedgcockii (Dearn.) Darker

The histopathology of Ploioderma hedgcockii on longleaf pine needles was examined. Abnormal host tissue was confined to the visible lesion and to tissues external to the endodermis where collapse of mesophyll cells was the predominant abnormality. Resin ducts exhibited necrosis and dissolution of epithelial cells. l Hyphae, intra- and intercellular, were frequent to profuse in inter-cellular spaces resulting from mesophyll cell collapse. Hyphae were external to the endodermis and appeared limited to the symptomatic tissue by an intercellular matrix at the lesion bound-aries Hysterotheca were subepidermal and appeared seated on the hypodermis. Asci appeared contain foui “two-stage” ascospores. The presence of a toxin was not indicated in the host/pathogen relationship.     

Effect of the Needle-cast Fungus Lophodermella sulcigena on Growth of Corsican Pine

Infection of current-year needles of Corsican pine near Aberdeenby Lophodermella sulcigena (Rostr.) v. Höhn. resulted ina 59 per cent reduction in the volume growth of the stem overa 12-year period; height increment was not affected significantly.     

The status of Crumenula sororia infections in crops of Corsican pine

Nodal cankers caused by C. sororia on Corsican pine were three times as common as internodal cankers. Natural infections reached maximum incidence on the fourth internode from the apex in branches and stems, but on stem internodes only on the ninth internode down. The longitudinal rate of canker spread was approximately 4 times that of the tangential rate. Crops of Corsican pine on N-facing slopes were more severely infected than those on S-facing slopes or flat areas, but in all cases the frequency of infection increased progressively with crop age. Cankers on individual stems showed a highly significant concentration on Northerly and Easterly aspects. Evidence is presented which suggests that the temperature differentials observed on different sectors of tree trunks may influence the duration of water films and hence limit the time period during which spore germination is possible.     

Effects of dessication on post-planting stress in bare-root Corsican pine seedlings

We examined the post-planting consequences of pre-planting exposure stress on two-year-old, bare-root Corsican pine (Pinus nigra Arnold. ssp. laricio var. Corsicana) seedlings. Seedlings were lifted from a nursery and exposed to ambient conditions for periods of up to 192 h before being planted in minirhizotrons. Exposure decreased seedling water potential, CO(2) assimilation rate, leaf conductance and new root elongation, and increased mortality after planting. During exposure, needle total nonstructural carbohydrates (TNC) concentration (expressed on a dry mass basis) decreased by 0.31 mg g(dm) (-1) h(-1); however, needle and root TNC concentrations remained high (> 100 mg g(dm) (-1)) at planting, even in those treatments leading to severe seedling mortality. More than 90% of the seedlings with predawn water potentials lower than -1.3 MPa at planting did not elongate new roots and did not survive, whereas a similar percentage of seedlings with a predawn water potential above this value at planting elongated new roots and survived, suggesting that this value corresponds to a turgor threshold below which new root formation is inhibited. At planting, embolization of xylem conduits in roots and shoots was low for seedlings in all of the exposure treatments.     

Effect of damaged pine needles on growth and development of pine caterpillar larvae

Chinese pine caterpillar (Dendrolimus tabulaeformis) larvae were fed with pine needles of different degrees of damage to evaluate the effects of pine needles on the growth and development of larvae. The results showed that the nutritional index of the larvae declines after feeding on the damaged pine needlings. The lowest amount of food ingested and voided feces, the lowest nutritional index, slowest development, lightest pupae and most mortality were found in those pine caterpillar larvae fed with pine needles which were 50% damaged. The damaged pine needles significantly affected the population dynamics of Chinese pine caterpillars. The nutritional indices of larvae fed with 25% and 75% damaged pine needles were similar. The nutritional index of the dark morphs was higher than that of the tinted morphs, however, their mortality was lower than that of the tinted morphs. This phenomenon was reversed at the later stage of development when the larvae were fed on 50% damaged pine needles. __________ Translated from Journal of Beijing Forestry University, 2005, 27(6): 83–88 [译自: 北京林业大学学报, 2005, 27(6): 83–88]     

Penetration of Cronartium flaccidum into pine needles

The penetration of Cronartium flaccidum into the cotyledons, primary needles and secondary needles of Pinus pinaster and P. nigra var, laricio was investigated. SEM examination showed that the fungus did not form appressoria and that the germ tube penetrated directly into the stomata.     

Effect of thinning on the development of compression wood in stems of Corsican pine

This study considered the effects of thinning on the development of compression wood in stems of 35-year-old stand of Corsican pine (Pinus nigra L.). Part of the stand had been thinned at 5-yearly intervals and part left unthinned. Twenty trees each from the thinned and unthinned stands were randomly selected and felled. Measurements were made on tree height, stem diameter, stem slenderness and canopy depth. Wood samples were removed from the central part of the main log and cross-sectional measurements made on ring width, basic density and compression wood content. Cross-sectional area of compression wood was found to be three time higher in stems from the unthinned trees in comparison with those from the thinned trees. No significant differences in mean radial ring width or basic density were found between treatments. Correlations indicated that, with increasing in stem diameter, compression wood content increased in the unthinned trees, while a decline in compression was observed in the thinned trees. Tree height was also positively correlated with compression wood content in unthinned trees, while no equivalent relationship was observed in thinned trees. Observations from this study, while not conclusive, suggest that phototropic stimulus may be producing stem inclinations in the unthinned stand as trees compete for space in the canopy, whereas crown competition has been largely eliminated in the thinned stand; and that this is responsible for compression wood levels recorded in this study.     

Survival to prescribed fire of plantation-grown Corsican black pine in northern Portugal

Context

The current fire regime threatens black pine (Pinus nigra Arn.) persistence in the Mediterranean Basin, which recommends larger-scale fuel treatments. Prescribed burning is an option for stand protection but its use in young stands (which are particularly at risk) is hindered by the scarce knowledge on post-fire tree survival.

Aims

The objectives were to characterize bark thickness as a fire-resistance trait in P. nigra and to describe how post-fire tree survival responds to tree size and fire effects in a 16-year-old plantation.

Methods

Bark thickness was related to diameter at breast height and height in the stem. Metrics describing tree size and stem and crown damage were measured 1?year after prescribed burning in 259 trees. Tree survival was modeled with logistic regression and Classification and Regression Tree analysis.

Results

Bark thickness increased linearly with diameter at breast height (dbh) and decreased with height in the stem. Tree survival was primarily a function of crown injury. Stem damage was an influent factor in small trees.

Conclusion

Due to thinner bark and lower tolerance to crown damage, young P. nigra trees are less fire-resistant than other Mediterranean pines, e.g., Pinus pinaster. Prescribed fire should not be attempted if dbh <10?cm. Mechanical clearing is the treatment of choice in young stands with a significant shrub layer.     

油松针叶枯黄原因调查研究

调查结果表明，承德避署山庄及其周边地区的油松针叶大量枯黄，侧枝枯死或整树枯死是由于松大蚜的严重危害所致。     

The effects of ultraviolet-B radiation on photosynthesis of different aged needles in field-grown loblolly pine

We examined the effect of supplemental UV-B radiation (290-320 nm) on photosynthetic characteristics of different aged needles of 3-year-old, field-grown loblolly pine (Pinus taeda L.). Needles in four age classes were examined: I, most recently fully expanded, year 3; II, first flush, year 3; III, final flush, year 2; and IV, oldest needles still present, year 2. Enhanced UV-B radiation caused a statistically significant decrease (6%) in the ratio of variable to maximum fluorescence (F(v)/F(m)) following dark adaptation only in needles from the youngest age class, suggesting transient damage to photosynthesis. However, no effects of enhanced UV-B radiation on other instantaneous measures of photosynthesis, including maximum photosynthesis, apparent quantum yield and dark respiration, were seen for needles of any age. Foliar nitrogen concentration was unaffected by UV-B treatment. However, the (13)C/(12)C carbon isotope ratios (delta(13)C-a time integrated measure of photosynthetic function) of needles in age classes II and IV were 3% (P < 0.01) and 2% (P < 0.05) more negative, respectively, in treated plants than in control plants. Exposure to enhanced UV-B radiation caused a 20% decrease in total biomass and a 4% (P < 0.05), 25% (P < 0.01), and 9% (P < 0.01) decrease in needle length of needles in age classes I, II, and IV, respectively. The observed decreases in delta(13)C, and F(v)/F(m) of the needles in the youngest needle age class suggest subtle damage to photosynthesis, although overall growth reductions were probably a result of decreased total leaf surface rather than decreased photosynthetic capacity. Needles of age class IV had lower light- and CO(2)-saturated maximum photosynthetic rates (39%), lower dark respiration (34%), lower light saturation points (37%), lower foliar nitrogen concentration (28%), and lower delta(13)C (14%) values than needles of age class I. Apparent quantum yield and F(v)/F(m) did not change with needle age. The observed changes in photosynthesis and foliage chemical composition with needle age are consistent with previous studies of coniferous trees and may represent adaptations of older needles to shaded conditions within the canopy.     

Comparison of methods for protein extraction from pine needles

Extraction of proteins from pine needles for proteomic analysis has long been a challenge for scientists. We compared three different protein extraction methods including sucrose, Tris-HCl and trichloroacetic acid （TCA）/acetone （TCA method） to determine their efficiency in separating pine needle proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS-PAGE） and two-dimensional PAGE （2D-PAGE）. Proteins were then separated by SDS-PAGE. Among three methods the method using sucrose extraction buffer showed the highest efficiency and highest quality in separating proteins. In addition, clearer and more stable strips were detected by SDS-PAGE using sucrose extraction buffer. When the proteins extracted using sucrose extraction buffer were separated by 2D-PAGE, more than 300 protein spots, with isoelectric points （PI） ranging from 4.0 to 7,0 and molecular weights （MW） from 6.5 to 97.4 kD, were observed. This confirmed that the method with sucrose extraction buffer was an efficient and reliable method for extracting proteins from pine needles.     

Planting stress, water status and non-structural carbohydrate concentrations in Corsican pine seedlings

Two-year-old Corsican pine (Pinus nigra ssp. laricio var. Corsicana) seedlings were either well watered or subjected to a moderate drought for one month before being lifted from the nursery bed on October 9 and transplanted. Well-watered, non-transplanted seedlings served as controls. Needle predawn water potential (Psi(wp)), non-structural carbohydrate concentrations and plant development (survival, bud break, shoot elongation) were assessed before and during the first growing season after transplanting. On April 16, just before bud break, Psi(wp) was lower for the well-watered + transplanted and drought-conditioned + transplanted seedlings (Psi(wp) = -1.45 and -1.83 MPa, respectively) than for the controls (Psi(wp) = -0.56). There was a close relationship between the Psi(wp) measured on April 16 and bud break, shoot elongation and plant survival during the following growing period. Above a Psi(wp) of -1.1 MPa, all plants developed normally. Between -1.1 MPa and -1.6 MPa, bud break, and thus shoot elongation, did not occur in all plants. Between -1.6 MPa and -2.1 MPa, the plants were characterized by the absence of shoot growth, but mortality was zero. Below -2.1 MPa, there was a large increase in plant mortality. On April 16, starch concentrations were markedly lower in the roots of transplanted seedlings than in the controls. There was a positive correlation between Psi(wp) and root starch concentration. The Psi(wp) (-2.3 MPa) at which complete starch depletion was observed in the roots corresponded to the Psi(wp) below which plants did not survive. These results suggest that mechanisms specifically linked to altered water status and metabolic processes associated with altered carbohydrate status are involved in transplanting stress; however, it was not possible to disentangle the two effects. Drought conditioning did not lead to a marked increase in soluble carbohydrate concentrations, as reported for other species, and did not increase plant tolerance to transplanting stress.     

An investigation of the influence of harvesting practice on the development of blue-stain in Corsican pine logs

In September 1991, at Thetford, East Anglia and at Inverness,north-east Scotland, a comparison was initiated between blue-staindevelopment in Corsican pine logs from trees felled and processedby harvesting machine and similar logs from trees felled andtrimmed out by chain-saw. Blue-stain was assessed in discs from batches of logs destructivelysampled at 2-week intervals after felling. At the more southerlysite of Thetford, stain was first observed after 4 weeks. Themaximum recorded area was 10 per cent of the wood surface ina sample analysed after 10weeks. In contrast, stain never exceeded,1.1 per cent of the wood surface at Inverness. Amounts of stainwere significantly greater with machine-harvested logs thanwith chainsaw-harvested logs and were correlated with the amountof bark removed or loosened during harvesting. The use of spikedrollers resulted in more stain than did the use of rubber rollers. The fungi isolated from stained wood included Sphaeropsis sapinea,Potebniamyces coniferarum and Ceratocystis coerulescens. Theseare species adapted to the colonization of wood exposed throughdamage to the overlying bark     

Effects of SO2 on photosynthesis and peroxidase activity in Scots pine needles

Short-term exposure to high concentrations of SO₂ caused a temporary decrease in the photosynthetic rate, while both short-term and long-term exposure to low concentrations of SO₂ increased photo-synthesis after the exposure. Low SO₂ concentrations did not cause any change in peroxidase activity. Thus peroxidase activity does not seem a suitable method in monitoring latent injury caused by low SO₂ concentrations.     

Acid phosphatase activity and phosphorus nutrition in Scots pine needles

From March to October, acid phosphatase activity and phosphorus (P) concentration were measured in four needle age classes of the upper and lower crowns of fertilized and unfertilized Scots pine (Pinus sylvestris L.) trees. Negative correlations between acid phosphatase activity and P concentration were observed in current-year needles and in needles in the upper part of the crown, whereas there was a positive correlation between enzyme activity and P concentration in older needles and in needles in the lower part of the crown. In May and October, needles of all ages showed increased acid phosphatase activity. The most sensitive response of acid phosphatase activity to phosphate supply and phosphorus status of the whole tree was seen in current-year needles on the first whorl where a 300% increase in acid phosphatase activity was observed in response to a decrease in foliar P concentration of 1.7-1.8 mg P g(DW) (-1).