Detection and transport of soluble antigens of Erwinia salicis and their role in symptom expression of the Watermark disease

An inproved method for the detection of soluble antigens of Erwinia salicis in leaves of Salix alba by ELISA is described. These antigens play a role in symptom expression of the Watermark disease. The antigen concentration in the leaves fluctuates strongly during the growing season. Presence of E. salicis inside willow trees could be determined without disturbing both host and pathogen.     

Detection of soluble antigens of Erwinia salicis in leaves of Salix alba by Enzyme-linked Immunosorbent Assay

Soluble antigens of Erwinia salicis are transported through the xylem vessels to the leaves of Salix species. These antigens can be detected by the use of the Enzyme-linked Immunosorbent Assay (ELISA) in willow trees in the absence of bacterial cells and are also produced in pure cultures. In this way populations of E. salicis occurring in stem or branches can be traced in the leaves. The possibilities for more general application in the detection of vascular parasites is discussed.     

两种催根药剂对龙眼葡萄插条的催根效果

比较了ABT生根粉2号和爆发性生根剂不同浓度和处理时间对龙眼葡萄插条的催根效果,结果表明:两种药剂对提高龙眼葡萄插条生根作用都较显著,以爆发性生根剂100×10-6处理效果最佳。     

Studies on Drepanopeziza salicis (Tull.) v. Höhnel,perfect state of Gloeosporium salicis West.

The development of the apothecium of Drepanopeziza salicis– the perfect state of Gloeosporium salicis– following the appearance of the microconidia has been described. The formation of both microconidia, which possibly have a spermatial function of mature ascospores and the incubation period of the ascospore-infection have been related to climatic conditions.     

我国主要栲属植物的地理分布

根据文献资料和标本馆记录及实地考察,对壳斗科栲属(Castanopsis)植物中的苦槠(C.sclerophylla)、甜槠(C.eyrei)栲树(C.fargesii)、南岭栲(C.fordii)、钩栲(C.tibetana)、罗浮栲(C.fabric)、刺栲、(C.hystrix)、鹿角栲(C.lam ontii)、黧蒴栲(C.fissa)等9种主要栲属植物的地理分布区进行研究,探讨栲属主要树种的分布特点。9种栲属植物呈镶嵌式分布。其中苦槠栲和甜槠是分布在我国最北的栲属树种,其最北可达安徽南部;甜槠栲在我国的分布最广、面积最大。刺栲在我国的分布分为2部分:一部分集中在我国西南地区;另一部分集中在长江以南部分地区。     

溪畔杜鹃的地理分布与园林应用

溪畔杜鹃为常绿灌木或乔木,具有很高的观赏价值。本文介绍我国溪畔杜鹃的地理分布,生态学特性,阐述其优良特性以及园林的应用领域,并对其在园林中的配置进行了分析。结果表明:溪畔杜鹃具备优良的观赏特性和生态学特性,适合用作盆花、专类园、花丛或花群等应用,是一种极具发展潜力的园林植物材料。     

The distribution of Phratora vulgatissima (Coleoptera: Chrysomelidae) on cultivated willows in Britain and Ireland

Insect samples were collected from the canopy of 24 willow short rotation coppice (SRC) sites on farmland in Britain and Ireland in 1995. The blue willow beetle Phratora (= Phyllodecta) vulgatissima (L.) (Coleoptera: Chrysomelidae), previously identified as the main defoliating pest of this crop, was recorded from 13 of these at varying levels of abundance. Data describing aspects of the environment at each site were also collected. These data were used to create potential explanatory variables for a regression analysis of beetle abundance. This analysis indicated that P. vulgatissima were most likely to occur and were more abundant at older willow sites on clay soils and at sites that bad certain free-living willow species growing nearby. Within sites, most willow clones sampled contained P. vulgatissima, although two, Salix burjatica‘Germany’ (‘Aquatica Gigantea’) and Salix mollissima‘Q83’ (Salix triandra × Salix viminalis), were avoided. Chrysomelid pest avoidance and clonal resistance could form part of an integrated pest management strategy for SRC crops.     

Geographical and seasonal influences on the distribution of fungal endophytes in Laurus nobilis

The species composition of the endophytic mycobiota in bark, leaves and twigs of Laurus nobilis were studied in Western Anatolia. Four sampling sites were selected; one of which was sampled twice, in spring and autumn. About 3892 fungal isolates obtained grouped into 85 morphological types. The 11 dominant species, with isolation frequencies >1.5%, were Alternaria alternata, Botryosphaeria sarmentorum, Colletotrichum dematium, C. gloeosporioides, Hendersonula sp., Paraconiothyrium sp., Phoma sp., three species of Phomopsis and Seimatosporium lichenicola. Numbers of fungal species isolated per tree differed between the sampled sites. Isolation frequencies of the dominant species, and other less frequent species, were dependent on the sampling site. The degree of endophytic infection and the diversity of fungal species were significantly higher in spring. Frequencies of all dominant species depended significantly on season, except for Stemphylium sp. and S. lichenicola. Analysis of the total endophytic mycoflora of the sampled trees suggested that geographical factors affects the endophytic distribution patterns more significantly than seasonal factors.     

Wolves, elk, willows, and trophic cascades in the upper Gallatin Range of Southwestern Montana, USA

We summarized the status of wolves (Canis lupus), elk (Cervis elaphus), and woody browse conditions during the 20th century for the upper Gallatin elk winter range in southwestern Montana, USA. During this period, wolves were present until about the mid-1920s, absent for seven decades, and then returned to the basin in 1996. A chronosequence of photographs, historical reports, and studies indicated willows (Salix spp.) along streams became heavily browsed and eventually suppressed following the removal of wolves, apparently due to unimpeded browsing by elk. However, after wolf establishment in 1996, browsing intensity on willows lessened in some areas and we hypothesized that, at both a landscape and fine scale, browsing pressure reflects terrain configurations influencing predation risk (nonlethal effects), in conjunction with lower elk densities (lethal effects). We measured browsing intensity and heights of Booth willow (S. boothii) along 3000 m reaches of the Gallatin River and a tributary to examine the potential influence of wolf/elk interactions upon willow growth. Where the Gallatin Valley is relatively narrow (high predation risk), willows began releasing in 1999 and by 2002 were relatively tall (150–250 cm). In contrast, willow heights along a wider portion of the Gallatin Valley, along the open landscape of the tributary, and an upland site (all low predation risk) generally remained low (<80 cm). We identified terrain and other features that may contribute to the perceived risk of wolf predation, by elk for a given site. Although alternative mechanisms are discussed, changes in willow communities over time following wolf removal and their subsequent reintroduction were consistent with a top-down trophic cascade model involving nonlethal and possibly lethal effects. If similar top-down effects upon vegetation hold true in other regions of North America and other parts of the world where wolves have been extirpated, wolf recovery may represent a management option for helping to restore riparian plant communities and conserve biodiversity.     

雪毒蛾越冬幼虫防治技术及防治指标研究

根据雪毒蛾ＳｔｉｌｐｎｏｔｉａｓａｌｉｃｉｓＬｉｎｎａｅｕｓ幼虫下树越冬，出蛰后经树干上树为害的活动特点，采用树干束草诱杀或选择强触杀性农药喷干的方法，进行早期防治，同时研究出杨树不同径级条件下的越冬代幼虫防治指标为１１６ｘ—３５８（诱集头／株）。     

皖西大别山区大鲵的地理分布及资源利用

根据皖西大别山区大鲵地理分布的实地调查,发现近年来大鲵数量锐减,分布区日趋缩小,资源面临衰竭,为此,对保护发展和合理利用大鲵资源,恢复该区大鲵自然种群数量进行了初步探讨。     

Geographical distribution of the Armillaria species in The Netherlands in relation to soil type and hosts

The geographical distribution of the annulate Armillaria species was studied in The Netherlands during the period 1983–1992. Armillaria gallica (incl. A. cepistipes), A. mellea and A. ostoyae appear to be widespread, the first two species being rather common on broad-leaved hosts growing on clay and loess soils, and the third species common on both broad-leaved and coniferous hosts on acid sandy soils. The distribution of the Armillaria species encountered was primarily determined by soil type. From a silvicultural point of view, A. ostoyae is the most important species, being pathogenic and occurring most frequently on sandy soils, the soil type predominantly used for forestry in The Netherlands.     

Geographical distribution of Aralia elata characteristics correlated with topography and forest structure in Heilongjiang and Jilin Provinces,Northeast China

The Araliaceae family consists of numerous species of medical plants of significant value as non-wood forest products. To conserve and culture these plants in natural forest stands is an important undertaking which should be implemented according to the relationship between forest structure and understory population. In this study, thirtyfive plots were established in natural A ralia elata stands. Taller individual and denser populations were found in the northern and in the eastern regions, respectively. Both population densities and individual leaf weight increased along longitude. In contrast, their relationship with elevation and DBH were negative. Along with the altitude gradient, both height and root-collar diameter increased but population density declined. Root-collar diameter and population density decreased with latitude and DBH, respectively. Overall, dominant trees unlikely enforced strong disturbance to the development of understory A. elata populations unless concerning some specific topographic factors.     

红檵木花叶病毒病——Ⅱ.发病原因及其防治对策

红檵木采穗母树、砧木、接穗带毒是引发红檵木花叶病毒病的根本原因,苗木生产、盆景制作、园林应用中的反复修剪和蚜虫危害加速了该病的传播和流行.加快红檵木无毒苗木繁育体系的建设、及时清除病株、切断病毒的传播途径、加强病虫防治是防治该病的有效措施.     

Geographic distribution,disease symptoms and pathogenicity of Phytophthora nemorosa and Phytophthora pseudosyringae in California,USA

During the course of surveys for Phytophthora ramorum in coastal forests of California and Oregon, P. nemorosa and P. pseudosyringae were frequently isolated from foliage and stems of the same hosts as P. ramorum. Both species ranged from central California to Oregon within 50 km of the Pacific Ocean. Both were also found in the Sierra Nevada Mountains. Phytophthora nemorosa was primarily found infecting trees in coast redwood forests and was most often isolated from bay laurel leaves (Umbellularia californica), bleeding cankers on the main bole of tanoak (Lithocarpus densiflorus), and leaf and small stem tissue of redwood (Sequoia sempervirens). Phytophthora pseudosyringae was primarily isolated from hosts found in coast live oak woodlands. Bay laurel was the most common host while infection of coast live oak (Quercus agrifolia) stems was less frequent. Inoculation studies confirmed the pathogenicity of P. nemorosa and P. pseudosyringae on their most common hosts.     

An artificial inoculation protocol for Uromycladium acaciae,cause of a serious disease of Acacia mearnsii in southern Africa

Uromycladium acaciae is the cause of a severe wattle rust epidemic in plantations of Acacia mearnsii (black wattle) in southern Africa. Research on the biology of this damaging rust is assisting in the development of control strategies. One strategy under investigation is the identification and deployment of resistant lines of A. mearnsii. Selection of resistant families currently relies on large-scale, time-consuming and expensive field trials. In this study, we present a detailed artificial inoculation protocol for U. acaciae, which can be used to screen for resistance. The results of an experiment that used the protocol to screen the relative resistance of 12 families of A. mearnsii to U. acaciae are also presented. The developed artificial inoculation protocol can also be used to investigate several other aspects of this host–pathogen system.     

The emergence of beech leaf disease in Ohio: Probing the plant microbiome in search of the cause

American beech (Fagus grandifolia) is the target of a newly emerging disease in North America called beech leaf disease (BLD) that affects and disfigures leaves and which can lead to tree mortality. Beech leaf disease may be caused by a newly recognized subspecies of the anguinid nematode Litylenchus crenatae subsp. mccannii, but the associations of this nematode with bacterial and fungal taxa are unknown. We examined microbial communities associated with beech leaves affected by BLD in a 16‐year‐old American beech plantation using molecular methods. We detected L. crenatae subsp. mccannii in anywhere from 45% to 90% of leaves depending on the degree of visual BLD symptoms. Approximately 37% of asymptomatic leaves contained L. crenatae subsp. mccannii, whereas 90% of buds associated with symptomatic leaves contained L. crenatae subsp. mccannii. We found that fungal communities on leaves and buds were unaffected by BLD, but bud and leaves had significantly different fungal communities. Bacterial communities on buds also were unaffected by BLD, but bacterial communities were significantly different between symptomatic and asymptomatic leaves suggesting that the nematode could be altering the community of bacteria on the leaves. Clone libraries indicate that Wolbachia, an intracellular endosymbiont of arthropods, was found only on symptomatic leaves and buds associated with either symptomatic or asymptomatic leaves. In addition, only symptomatic leaves contained taxa in the genus Mucilaginibacter, which previous studies suggest could produce exopolysaccharides. These bacterial taxa could represent a marker for the vector of L. crenatae subsp. mccannii that enables spread between trees and a possible endosymbiont that could facilitate nematode feeding and establishment on nematode infested leaves. Our results are the first to examine changes to the leaf microbiome of this newly emerging pest and may aid identification of mechanisms associated with the spread and success of L. crenatae subsp. mccanni.     

枣缩果病生防菌筛选及防治研究

为了研究枣缩果病的生物防治效果,给生产防治提供参考依据,采用抑菌圈法和菌丝生长抑制法对11个细菌菌株进行枣缩果病菌Alternaria alternata的室内抑制试验,筛选出Y2、Y4、CN181、G1、G4、G6、G8等7个菌株对枣缩果病菌Alternaria alternata的生长均有抑制作用,其中Y2、Y4、G1等3个生防菌株对链格孢菌孢子萌发的抑制作用最明显;将3个细菌制成细菌制剂,按比例稀释后喷洒到林间,设置异菌脲为化学药剂效果对照,林间防治试验结果表明:异菌脲的防治效果最稳定,防治效果达到80%,其次是Y4,防治效果达到60%以上,再次是Y2,G1基本没有防治效果。     

广东象头山国家级自然保护区蜻蜓目昆虫区系地理研究

2017 年 3 月至 2019 年 12 月对象头山国家级自然保护区蜻蜓目昆虫进行了持续调查,鉴定和统计到 122 种蜻蜓,隶属于 14 科 74 属,蜻科种类最多,有 33 种,其次为春蜓科,有 28 种,优势种为华艳色蟌 Neurobasis chinensis、胭翅绿色蟌 Mnais mneme、并纹小叶春蜓 Gomphidia kruegeri、海南亚春蜓 Asiagomphus hainanensis、笛尾弓蜻 Macromia calliope、黑尾灰蜻 Orthetrum glaucum、黄蜻 Pantala flavescens、庆褐蜻 rithemis festiva 等。在世界动物地理区系类型方面,东洋界种类较多,有 92 种,占总数的 75.41%;东洋界 – 古北界类型的种类相对较少,只有 28 种,约占总数的 22.95%,广布种有 2 种;中国动物区系地理方面,有 10 种分布型组合,华南区的种类最多,有 50 种,占 40.98%;跨西南区的有 13 种,占 10.66%,跨华中区的有 19 种,占 15.77%;跨西南区、华中区、华北区的种类也较多,有 20种,占 16.39%。蜻蜓目昆虫区系分析结果与象头山自然保护区所处地理位置相一致。     

A Geographical Analysis of the Swedish Woodfuel Market

The geographical variation in Swedish woodfuel market characteristics for the district heating sector has been studied using Geographical Information Systems (GIS) and cross - sectional Tobit analysis. The results indicate that local availability and competition for woodfuels influence the woodfuel consumption at inland heating plants. The factors affecting the decision to use woodfuel at heating plants close to seaports, however, were not captured by the model, suggesting that coastal location reduces dependency on the local woodfuel market. The effects of changes in local woodfuel availability on woodfuel use by an inland heating plant are presented and discussed.