Evaluation of various parts of the paw paw tree, Asimina triloba (Annonaceae), as commercial sources of the pesticidal annonaceous acetogenins.

Various plant parts of the paw paw tree (Asimina triloba Dunal, Annonaceae) were extracted and partitioned to concentrate the mixture of acetogenins into a standardized pesticidal extract (F005). A bioassay with brine shrimp larvae (Artemia salina Leach) was used to determine the relative potencies of the various extracts. The small twigs (0-0.5 cm diameter) yielded the most potent extract (LC50 = 0.04 ppm); the stem wood (LC50 = 4.9 ppm) and leaves (LC50 = 53.7 ppm) yielded the poorest activities. The unripe fruits, seeds, root wood, root bark, and stem bark were notably potent and, generally, yielded > 2% of their dry weight as F005. The smaller diameter stems were more potent than the larger stems. We conclude that, by pollarding the trees, the entire twigs and small branches of paw paw could be processed to produce a potent acetogenin mixture; this biomass could be made available in quantities needed for commercialization of the pesticidal product and could be renewable through regrowth from the parent trunk and larger branches.     

Patterns in the within-tree distribution of the emerald ash borer Agrilus planipennis (Fairmaire) in young, green-ash plantations of south-western Ontario, Canada

1 The emerald ash borer Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is a serious exotic pest of ash trees (Fraxinus spp.) in North America, and is responsible for the deaths of millions of trees in Ontario and Michigan. One of the greatest challenges facing the successful management of the pest is the ability to accurately detect its presence in a tree. 2 Observations were made on A. planipennis larval feeding galleries found within 65 young, green‐ash trees cut from plantations in Essex County, Ontario, Canada. The within‐tree distributions of feeding galleries were described in relation to height‐above‐ground, stem diameter, bark thickness and stem aspect. 3 Galleries were not distributed randomly or evenly; minimum boundaries of stem diameter and bark thickness and a maximum boundary of height‐above‐ground were detected. Indications of maximum boundaries for stem diameter and bark thickness were also observed. Galleries were found most often on the south‐west side of the tree. 4 Using the technique of upper boundary regression, we were able to identify significant quadratic relationships between A. planipennis gallery density and stem diameter and bark thickness, as well as a significant negative linear relationship between gallery density and height‐above‐ground. 5 Agrilus planipennis gallery density in newly‐infested trees was lower than in previously‐infested trees, and was observed to peak at smaller stem diameters and bark thicknesses than in previously‐infested trees. 6 Survey teams would increase their probability of detecting new A. planipennis infestations by initiating searches for exit holes and feeding galleries in trunk sections and branches of approximately 7 cm in diameter.     

Respirationsintensität in Stäinmen, Zweigen und Blältern von Laubbäumen im tropischen Regenwald und in temperierten Wäldern

Respiratory Activity in Stem, Branches and Leaves of Evergreen Trees in Tropical Rain Forest and of Deciduous Trees in Temperate Climate.— Reduced to the same temperature, the respiratory activity of different parts of tropical rain forest trees and of corresponding parts of temperate deciduous trees is approximately the same. In particular, the leaf-blades of Danish deciduous trees and of tropical rain forest trees from the lowland of Côte d'Ivoire (57° north. lat.) have nearly the same respiratory activity at 20°C: the blades of the extreme shade leaves about 0.1 mg CO₂, those of the extreme sun leaves about 0.8 mg CO₂ per 50 cm² (one side only) per hour at 20°C. This is in accordance with the fact that the blades of shade leaves, respectively Sim leaves, of the tropical rain forest trees are built in the same way as the blades of deciduous trees in our temperate climate. The respiratory activity shows that they have the same “concentration” of living cells, the same “concentration” of active plasma. The respiratory activity of trunk and branches depends mainly on three factors: diameter of the stem-section or branch-section, nutritional condition, and temperature. The respiratory activity of trunk and branches of hardwoods in temperate climate is also dependent on the season. The estimations on stems and branches from the temperature trees were made In July–August. There was in most cases a remarkable agreement in respiratory activity between temperate and tropical hardwoods: Branches with a diameter of about 0.5–2 cm have a respiration of about 70–100 mg CO₂ per kg fresh weight per hour at 20°C. Trunk sections with a diameter over 20 cm have a respiratory activity of about 3–5 mg CO₂, per kg fresh weight per hour at 20°C. In the older parts of a stem most of the cells are dead. The agreement in respiratory activity probably means that the “concentration” of living cells in the older parts of the stem of tropical and temperate hardwoods is the same.     

SEASONAL OCCURRENCE OF XYLEM EMBOLISM IN SUGAR MAPLE (ACER SACCHARUM)

Xylem embolism, the reduction of water flow by air-filled vessels, was measured in a stand of 5- to 8-year-old sugar maple (Acer saccharum Marsh.) saplings growing in a nursery bed in northwestern Vermont. Embolism was quantified as percentage loss in hydraulic conductivity of trunk and branch segments relative to maximum values obtained by removing air from vessels by repeated high pressure (173 kPa) perfusions. Ten segments per tree were cut from 6 trees for each of 11 measurement periods spaced at roughly monthly intervals from May 1986 to June 1987. During the 1986 growing season, embolism increased significantly from 11 to 31% in the larger branches and trunk (segment diameter #8805;0.5 cm), but remained at about 10% in twigs (segment diameter <0.5 cm). This was unexpected because the greatest water stess and thus potential for embolism occurs in twigs. During the winter, embolism increased throughout the trees and the trend with diameter was reversed; by February, small twigs were 84% embolized vs. 69% for larger branches and trunk. Dye perfusions showed that winter embolism in trunks was localized on the south side; this may have resulted from water loss by sublimation or evaporation in the absence of water uptake. Beginning in late March, embolism decreased throughout the trees to approximately 20% in June. This decrease was associated with positive xylem pressure of at least 16 kPa which may have originated in the roots, because weather conditions at the time were unfavorable for the generation of stem pressures characteristic of Acer species in early spring.     

The relationship between bark peeling rate and the distribution and mortality of two epiphyte species

Tree bark characteristics influence epiphyte establishment and survival and consequently the way in which epiphytes are distributed on trees. Tree species with peeling bark have been reported as poor epiphyte hosts. We analyzed the distribution and seedling mortality of two Tillandsia species (Bromeliaceae) in relation to rate of bark peeling of Bursera fagaroides (Burseraceae). The highest peeling rate (0.12% per day) took place on the trunk and the lowest rate on twigs (0.04% per day; branches ≤2 cm in diameter). The highest proportion of Tillandsia plants appeared on twigs. The distributions of juvenile and adult plants on twigs were higher than those expected based on the distribution of first-year seedlings, suggesting that on twigs, survival could be greater than on trunks and branches, canopy areas where peeling is faster. On the trunk and branches, in contrast, the proportion of juveniles and adults were similar to or less than that expected for first-year seedlings. The main cause of mortality was peeling and the area of minor overall mortality was the trunk, suggesting that this area should be favored as the main distribution area for the Tillandsia species but is not. Our results show that the peeling rate of B. fagaroides depends on branch size and suggest that the Tillandsia distribution depends not only on peeling rate but also on seed dispersion. We suggest that to colonize B. fagaroides epiphytes would either have adaptations to counteract the peeling rate or should occur in the areas of lowest peeling rate located in the exterior crown of trees.     

Distribution and survival of overwintering adults of the Dutch elm disease vector, Hylurgopinus rufipes (Coleoptera: Scolytidae), in American elm trees in Manitoba

Abstract 1 The native elm bark beetle, Hylurgopinus rufipes, is the principal vector of Dutch elm disease in Manitoba, Saskatchewan and North Dakota, and disease management measures include applying residual insecticides to the lower part of elm tree trunks where the adult beetles overwinter. 2 In American elm trees in southern Manitoba, we counted entrance holes produced by beetles then felled and dissected trees to determine numbers of tunnels and numbers and survival of overwintering beetles. 3 Densities of entrance holes, tunnels and beetles followed a logistic relationship with tree trunk diameter; densities were near zero at diameters < 10 cm and reached a site‐specific asymptote at diameters > 20 cm. 4 Asymptotic densities of holes, tunnels and beetles in samples from 55 to 190 cm above the ground were, respectively, 22%, 22% and 0.7% of those within 25 cm of the ground. 5 Within the height range 0–190 cm, the proportion of living beetles declined steeply with increasing height. 6 Average density of holes at height 0–25 cm estimated from a sample of several trees of diameter ≥15 cm could be used to predict the asymptotic maximum density of overwintering beetles in the site; predictions of beetle densities for individual trees were not reliable.     

四种类型栓皮栎栲胶含量

为了阐明不同类型(薄皮深裂、薄皮浅裂、厚皮深裂、厚皮浅裂)栓皮栎各器官栲胶含量,系统采集了秦岭南坡商州区4种类型的栓皮栎不同径级植株根、主干木材、叶片、枝条和树皮样品,用紫外光分光光度法(UV Spectrophotometry)测定了4种类型栓皮栎不同器官栲胶含量,分析了林木生长与栲胶含量的关系。结果表明,(1)4种类型栓皮栎的根、主干木材、叶片、枝条和树皮单宁含量平均值分别为2.64%—3.02%、1.74%—2.02%、6.63%—7.21%、4.69%—5.10%、8.87%—9.46%,叶片、枝条和树皮均可以作为栲胶生产主要原材料。(2)不同类型各器官单宁含量存在极显著差异(P0.01),4种类型的树皮、叶片、枝条单宁含量均表现为:厚皮深裂型厚皮浅裂型薄皮深裂型薄皮浅裂型;根部和主干木材在4种类型间单宁含量表现为:薄皮深裂型薄皮浅裂型厚皮深裂型厚皮浅裂型;厚皮深裂类型的栓皮栎是提取栲胶的最佳类型。(3)4种类型栓皮栎各器官单宁含量与胸径呈显著正相关,各器官单宁含量随着栓皮栎胸径增大而增多,并最终趋于稳定,在第Ⅳ径级(胸径20.1—25cm)时,栲胶含量均值最大。因此,栲胶生产可以高效利用第Ⅳ径级及其以上径级的栓皮栎,并对第Ⅳ径级以下栓皮栎进行定向培育和重点保护。     

The vertical gradient of bark pH of twigs and macrolichens in a Picea abies canopy not affected by acid rain

Abstract:The pH of 192 thin, even-aged twigs from 4 height levels of 12 randomly selected trees within a boreal Picea abies canopy naturally exposed to rainfall with a high pH (>5·2) was measured. The largest variation in bark pH was due to the height above the ground. However, a highly significant horizontal variation between trees was also found, apparently due to small-scale soil variations. The biomass of alectorioid lichens increased with increasing height above the ground to at least 12 m, a height interval with fairly constant pH values. The uppermost twigs had an unusually high pH and an abnormal species composition for P. abies, with dominance of the foliose Melanelia exasperatula. The canopy hosted several cyanobacterial lichens, but these were scattered and had low biomass, restricted to lower branches of the trees with the highest bark pH.     

Fusarium solani association with branch and trunk cankers on citrus weakened by cold weather in Florida

Injury or inoculation of apparently healthy citrus trunk bark and wood with Fusarium solani immediately prior to and after the December 1983 freeze resulted in cankers similar to natural branch and trunk cankers which formed on trees following the freeze. Fusarium solani was consistently isolated from active lesions of natural and induced cankered bark. Phytophora spp. were not isolated from cankered tissue. Earliest cankers appeared as a water-soaked area under the bark around the point of inoculation, later F. solani sporodochia formed on the bark surface. Older cankers became dry and cracked but produced no gum. Canker size ranged from 10–90 cm vertical diameter in spring 1984 inoculations but were only several cm diameter following late summer inoculations. Active cankers developed again after inoculation following the January 1985 freeze. Similar cankers were produced on Hamlin sweet orange stems inoculated with F. solani.     

我国特有植物银杉的资源、分布及其环境

我国银杉自1955年发现以来,陆续发现了它的新分布,至今已知在四省、区7个分布区的30多个分布点上,自然生长着银杉3200余株。它们是:广西花坪林区(越城岭南部)6个点有银杉1040抹,其中高5米以上的68株,1～5米的49株,1米以下的923株,最高21.1米,最大胸径83厘米;广西大瑶山4个点有银杉143株,其中高10米以上的94株,1～3米的3株,1米以下的46株,最高30米,最大胸径79.2厘米;湖南罗汉洞(越城岭北部)2个点有银杉58株,5米以上的有45株,最高18米,最大胸径43厘米;湖南罗霄山脉八面山有银杉707株,高1米以上的334株,最高24米,最大胸径46厘米;四川南川金佛山(大娄山东段北部)6个点有银杉527株,其中成年树400余株,最高17米,最大胸径50厘米;百枝山有银杉52株,最高8米,最大胸径27厘米;贵州道真沙河林区(大娄山东段南部)3处12个点有银杉729株,其中高5米以上的105株,2～5米的209株,1～2米的111株,1米以下的304株,最高18.8米,最大胸径48厘米;贵州桐梓白菁有银杉10株,高4～5米的2株,1～3米的6株,1米以下的2株。 银杉分布区范围自北纬24°5′～29°13′14″,东经107°10′～113°40′。其垂直分布自海拔940～1840米,金佛山银杉分布最高,为1600～1840米;罗汉洞银杉分布最低,为940～1060米。分布区内,年均温8.2°～17℃,绝对最低温     

16S rDNA Sequence Analysis of Bacterial Isolates from Die-back Affected Sissoo Trees (Dalbergia sissoo Roxb.) in Bangladesh

A new form of disease called ‘die‐back’ has been established in Dalbergia sissoo trees. This disease has reached epidemic proportions in Bangladesh as well as in other countries of South Asia and is characterized by browning of the leaves, signs of wilting, and trunk lesions with gum flow. The trees die within a few months. In order to investigate the causes of this die‐back disease, samples were taken for a first trial in the Rajshahi division at two sites around Sherpur. For the isolation of bacteria, surface‐sterilized plant material (leaves, twigs and trunk bark) from diseased trees was transferred to LB medium and incubated. After isolation of single colonies, various bacteria species could be identified by polymerase chain reaction analysis with two primers specific for highly conserved sequence regions in the bacterial 16S rDNA and by sequencing. First indications for the presence of bacteria with phytopathogenic potential were found.     

Bark consumption of voles in relation to snow cover, population density and grazing impact

The voles Microtus agrestis and Clethrionomys glareolus consume more bark in north than in south Sweden in spite of lower availability in the former area due to snow-pressed ground. Field experiments with genetically homogeneous aspen sticks demonstrated that this pattern reflects differences in animal behaviour and not differences in plant palatability. Within a region consumption in snow-pressed areas was usually less than in subnivean spaces or runways. The amount of bark consumption was generally correlated with population density and amount of grazing impact. Great differences in bark consumption between north Swedish areas with high peak vole populations and south-central Swedish areas with moderate peak numbers imply that nutrition is of different importance at population declines in different regions. The ability of voles to move into snow-pressed areas and locate woody sticks in the snow suggests that control of ground cover will not protect tree seedlings at reforestation.     

Vertical stratification in the spatial distribution of the beech scale insect (Ultracoelostoma assimile) in Nothofagus tree canopies in New Zealand

Abstract. 1. The degree of infestation by New Zealand sooty beech scale insects (Ultracoelostoma assimile, Homoptera: Margarodidae) varies dramatically among adjacent southern beech trees (Nothofagus spp., Fagaceae), but has previously been assumed to be uniformly or randomly distributed within individual host trees. In this study, a full‐census survey was conducted from ground level to canopy level on 14 naturally occurring, canopy‐dominant red beech (Nothofagus fusca) trees (size range 38.7–107.6 cm diameter at breast height) to determine the degree of within‐tree heterogeneity in herbivore density. 2. The within‐tree distribution of the sooty beech scale was vertically stratified and highly heterogeneous, with the greatest densities occurring on bark surfaces in the canopy rather than on the trunk, and on the lower rather than upper sides of the branches. The spatial distribution was strongly negatively correlated with trunk and branch diameter, and increasing bark thickness (as a function of diameter) provides a plausible explanation for differences in the establishment and population density of sooty beech scale insects with trunk and branch size. Furthermore, there was a significant change in the spatial distribution of scale insect populations on trunks and branches of trees of increasing diameter at breast height. This indicates a strong temporal component to the spatial dynamics of the sooty beech scale insect driven by changing host phenology. Future studies on phytophagous insects infesting large host trees need to consider more explicitly changes in population dynamics through space and time. 3. Because of the high degree of within‐tree heterogeneity in population density, the total population size of scale insects on an individual tree could not be predicted from any measure of population density low on the trunk. However, the dry weight biomass of sooty mould fungi growing on the ground beneath infested trees was a remarkably accurate predictor of the total population size of scale insects. The use of sooty mould fungi as a relative measure of population size could be incorporated into studies of other honeydew‐producing hemipterans, since the growth of sooty mould is a distinctive feature synonymous with high concentrations of honeydew production worldwide.     

Extraction of water from Eucalyptus trees for analysis of deuterium and oxygen-18: laboratory and field techniques

This study investigated a methodology for sampling and extracting water from Eucalyptus spp. for analysis of stable isotopes of water. Firstly, water of known isotopic composition was extracted from stems of seedlings of Eucalyptus spp. by azeotropic distillation using three solvents (hexane, toluene and kerosene) in laboratory and glasshouse experiments. Kerosene and toluene gave the most accurate extractions, with a small negative bias (～-2‰ for δ²H and ～-0.4‰ for δ¹⁸O) due to incomplete extraction. This bias was not evident in further experiments, using kerosene, where water was extracted from stems and roots that had been pre-treated in a manner that more closely reflected field conditions. Secondly, variation in δ²H in trees was investigated in the field to determine an accurate and convenient place for sampling. There was no significant difference in δ²H between water extracted from trunk sapwood and whole twigs, even twigs close to leaves, in samples taken from four Eucalyptus spp. at two field sites. The results mean that the most convenient part of the tree can be sampled. Also, there was little difference in δ²H between sapwood and heart-wood samples, although small increases (～ 2‰) in δ²H were observed in bark of trunks and twigs. Tree roots (15–25 mm diameter) had similar δ²H values to the surrounding soil in many cases, especially surface (<0.2 m depth) roots, rather than having δ²H values similar to twigs of the trees. These roots were absorbing water from surrounding soil, but not contributing significant quantities of water to the tree canopy. Thus, the δ²H of root water is not a good indicator of the isotopic composition of water in the upper parts of Eucalyptus trees.     

Trunk implanted zinc-bentonite as a source of zinc for apple trees

Summary The feasibility of zinc supply to apples (Malus spp. var. Golden Delicious) by various Zn-bentonite preparations implanted in the trunk was studied. A preliminary experiment included four preparations and was conducted in one plantation in 1980. A larger scale experiment in 1981, tested Zn-bentonite (ZnB) and Zn-bentonite + ZnEDTA (ZnBEA) in four plantations in the south, center and north of Israel. Clay tablets were implanted in holes drilled in the tree trunk in April. The youngest, fully developed leaves on the new growth were sampled periodically and Zn content was determined.ZnB and ZnBEA implanted at the rate of 15 mg Zn/cm trunk circumference significantly increased Zn content above that of the control trees until mid-September. The ZnBEA preparation supported significantly higher leaf concentrations than the ZnB preparation. Peak concentrations in trees treated with the ZnBEA preparation were 75.8, 47.4, 38.4, and 23.7 ppm in the four plantations and occurred in May. The Zn concentration in the youngest leaves decreased during the season but there was evidence that in some cases Zn behaved as a phloem mobile element. Soil, climate and previous zinc treatments affected considerably the Zn concentration found in leaves in the four plantations making it impossible to identify a single critical concentration level.No damage to the trees was observed as a result of the drilling and implantation of the clay tablets. Clay analysis at the end of the season showed that about two-thirds of the Zn added to the trees was used. The amount of Zn supplied per tree in the implantation procedure was 80–90% lower than that supplied in the routine spraying operations.     

Johansson revisited: the spatial structure of epiphyte assemblages

Question: Vertical zonation schemes are widely used in biodiversity studies with vascular epiphytes as a tool to capture spatial distribution patterns, the one most commonly used was proposed by Johansson more than 30 years ago. Does a survey of the epiphytes found on larger trees really yield a representative sample of the local community? Location: Lowland rainforest of the San Lorenzo Crane Plot, Republic of Panama. Methods: A complete census of the vascular epiphytes on all trees > 1 cm DBH in 0.4 ha of undisturbed lowland forest was analysed with both cluster and discriminant analysis to detect groupings of epiphyte species. Results: Six different groups of species were detected, five of them preferring different substrates on larger trees (as defined by (1) the height above ground at the attachment site, (2) the diameter of the substrate and (3) the occurrence on stem vs branches/twigs) and resembling to some extent the original Johansson zones. A sixth group of epiphytes, comprising ca. 10% of all taxa, was almost always found on small diameter stems and branches of trees with small DBH at lower and intermediate heights within the forest. Conclusions: Applying pre‐established zonation schemes may lead to misleading results in biodiversity studies with epiphytes. Important aspects of spatial distribution patterns may be missed, and the determination of relative species abundances may carry a strong quantitative and qualitative bias when analyses rely completely on epiphytic plants found on larger trees.     

猕猴桃溃疡病流行的生态因子及药剂对病菌的抑菌作用

经5年系统研究得出,影响猕猴桃溃疡病发生流行的特点是,海拔750m以上的果园发病重,向阳坡发病重于背阳坡,不同品种发病差异显著,金丰品种易感病,金魁品种高度抗病;树龄越大,病株率越高;不同枝龄比较,一年生枝条病枝死亡率和枝条死亡率最高.6种药剂以加瑞农和硫酸链霉素抑菌效果最好.     

猕猴桃溃疡病流行的生态因子及经剂对病菌的抑菌作用

经5年系统研究得出,影响猕猴桃溃疡病发生流行的特点是,海拔750m以上的果园发病重,向阳坡发病重于背阳坡,不同品种发病差异显著,金丰品种易感病,金魁品种高度抗病;树龄越大,病株率越高;不同枝龄比较,一年生村以条病枝死亡率和枝条死亡率最高.6种药剂以加瑞农和硫酸链霉素抑菌效果最好。     

Biosynthesis of friedelane and quinonemethide triterpenoids is compartmentalized in Maytenus aquifolium and Salacia campestris

Maytenus aquifolium (Celastraceae) and Salacia campestris (Hippocrateaceae) species accumulate friedelane and quinonemethide triterpenoids in their leaves and root bark, respectively. Enzymatic extracts obtained from leaves displayed cyclase activity with conversion of the substrate oxidosqualene to the triterpenes, 3beta-friedelanol and friedelin. In addition, administration of (+/-)5-(3)H mevalonolactone in leaves of M. aquifolium seedlings produced radio labelled friedelin in the leaves, twigs and stems, while the root bark accumulated labelled maytenin and pristimerin. These experiments indicated that the triterpenes once biosynthesized in the leaves are translocated to the root bark and further transformed to the antitumoral quinonemethide triterpenoids.