毛竹枯梢病病原菌致病机制及防治技术

毛竹枯梢病病原为竹喙球菌Ｃｅｒａｔｏｓｐｈａｅｒｉａ ｐｈｙｌｌｏｓｔａｃｈｙｄｉｓ Ｚｈａｎｇ。病原菌在１０％毛竹煎汁蔗糖培养基（Ｂ＋Ｓ），２５℃，１２小时明暗交替条件下培养４０￣５０天孢子量最多。病原菌分泌的毒素是一种还原性多糖，是致病的主要成分，在２０℃￣２５℃、振荡、连续黑暗和ｐＨ６条件下培养１２天产毒最多。病害的发民气候和竹林经营管理水平密切相关。通过实施清除病原，隔断侵染源、钩梢、垦复     

从桔蚜上分离的一种致病镰刀菌

从福建省南平市桔蚜虫尸上分离的一株镰刀菌 ,病原鉴定为镰刀菌属 (FusariumLinkexFn)的砖红镰孢 (FusariumlateritiumNees .)。病原菌在PDA培养基上生长旺盛 ,10～ 3 5℃均可生长 ,生长适宜温度为 2 0～2 6℃ ,2 5℃下培养 3d后可产孢。分生孢子萌发最适宜温度为 2 0～ 2 5℃ ,最适宜的相对湿度为 96%～ 10 0 %。对桔蚜若虫的毒力测定表明 ,砖红镰孢对桔蚜具有较强的致病力 ,其LC50 为 2 71× 10 7个孢子·L- 1 ,LT50 为2 2 1～ 6 3 4d(在 1 0× 10 1 1 ～ 1 0× 10 7个孢子·L- 1 浓度下 )。用砖红镰孢菌液田间防治桔蚜 ,死亡率达91 80 %。     

榆树干枯病初探

:榆树是华北地区的主要造林树种 ,榆树干枯病能引起榆树枝干干枯死亡 ,是榆树的重要病害 ,为了探明该病的病原菌 ,于 1 997～ 2 0 0 0年对榆树干枯病的病原进行了反复的分离培养与接种试验 ,找到了该病的致病菌     

杨歧山毛竹枯梢病发生规律及综合防治技术

毛竹枯梢病的发生与气候和竹林的经营管理水平密切相关。通过实施清除病原，隔断侵染源、钩梢、垦复、施肥、烟剂防治等综合防治技术，使病害发生面积下降了90％，消灭了重度和中度危害区。发病率和感病指数分别下降了94％和85％。     

由聚生小穴壳菌引起的NL895杨水泡型溃疡病

通过在PDA培养基上对NL895杨苗木水泡型溃疡病,病原菌进行了分离培养鉴定和致病性试验。结果证明,根据菌落培养特性、病原菌形态、病害症状和致病性试验,确定聚生小穴壳菌是NL895杨水泡型溃疡病病原,1年生苗木上的发病率高达50%～70%。NL895杨是聚生小穴壳菌的新寄主。     

杜松赤枯病病原菌的研究

阐述了杜松赤枯病病原菌的研究结果 ,研究表明交链孢 (Alternariasp )和茎点霉 (Phomasp )是杜松赤枯病的主要致病真菌 ;两种病原菌均喜偏酸性的条件 ,菌丝生长发育的适宜pH值是 5～ 7;菌丝生长的适宜温度是 2 0～ 30℃ ,孢子萌发的适宜温度是 15～ 2 5℃ ,2 0℃时萌发率最高 ;Al ternariasp 在相对湿度 90 %以上能较好萌发 ,Phomasp 在湿度 10 0 %时才能萌发 ,在水滴中萌发率最高 ;两种病原菌对云杉和丹东桧的嫩枝叶也有较强的致病性     

毛竹根际新黑曲霉的解磷特性及促生作用

[目的]探究毛竹根际微生物新黑曲霉(Aspergillus neoniger)JXBR16对土壤难溶性磷酸盐的溶磷作用及对毛竹的促生效果。[方法]采用液体发酵培养法研究该菌株对Ca_3(PO_4)_2、CaHPO_4、FePO_4、AlPO_4和植酸钙等5种难溶性磷酸盐的溶解能力及碳源、氮源、pH、装液量和盐离子等因素对其解磷能力的影响;并采用温室盆栽法评价该菌株对毛竹实生幼苗的促生作用。[结果]表明,新黑曲霉对5种难溶性磷酸盐均具有较好的溶解能力,其中对FePO_4、CaHPO_4的溶解能力最佳,解磷量分别达3 208.31和3 027.09 mg·L~(-1);在碳源为蔗糖或葡萄糖、氮源为硫酸铵、初始pH值3.5、装液量2/5、温度25℃和盐离子浓度为0～1.0 g·L~(-1)条件下新黑曲霉的解磷能力最佳。施用该菌株180 d后毛竹根际土壤有效磷和矿质氮分别提高37%和41%,植株根、茎和叶磷含量分别提高了95%、102%和43%;毛竹地径、苗高和生物量分别比对照显著提高了44%、47%和50%。[结论]新黑曲霉能够有效增强南方红壤区毛竹林土壤磷的供给,促进植株养分吸收利用,并提高毛竹的生长,具有应用于竹林生物菌肥研制和开发的巨大潜力。     

毛竹枯梢病大面积综合治理技术研究

毛竹枯梢病是南方毛竹产区一种危险性病害，也是森林植物检疫对象。湖南省１９９１年首次发现４００３ｈｍ２竹林严重受害。根据病害为一次侵染的单循环病害和病原致病性弱的特点，通过在大面积范围内采取以清除病源、隔断侵染源、幼竹钩梢等消灭病原为主的措施，结合对竹林进行垦复施肥，提高寄主的抗性；对危害中等以上的竹林辅以杀菌烟剂进行防治的综合治理技术，有效地控制了病害，消灭了中等危害和严重危害区，轻病区范围控制在１０１２ｈｍ２，发病率下降了８８６％，病情指数下降了９０４％。     

桉树溃疡病菌的生物学特性研究

经鉴定,桉树溃疡病的病原为Phoma eucalyptica Sacc.。该病原菌菌丝生长的最适温度是25～30℃,最适pH为5～7.5。病原菌分生孢子在25℃下24 h内萌发率93%,葡萄糖和蔗糖溶液对孢子的萌发有一定促进作用。病原菌对高温的耐受性较强,菌丝和分生孢子的致死温度分别为58℃和65℃。病原菌菌丝和孢子通过伤口侵入寄主体内,无伤接种不发病。     

大兴安岭人工林结构现状及调整措施

1　调查区自然概况调查区地处大兴安岭东坡 ,伊勒呼里山横贯本区中部。气候冬季严寒漫长 ,夏季温热短暂。年平均气温 - 2～ 5℃ ,≥ 10℃积温为 110 0～ 2 0 0 0℃ ,生长期 90～ 110天 ,年平均降水量 45 0～ 5 0 0 mm,相对湿度 70 %～ 75 %。土壤多为棕色针叶林土 ,植被为落叶松针阔混交林植被类型。2　调查方法2 .1　调查区区划植被的成活和生长与气温密切相关 ,其生理作用的强度和温度之间存在线性指数关系。本次调查根据吉良龙夫 (日本 )提出的简便积温指标—温暖指数 (WI)公式WI =∑ni=1(ti - 5 )式中　 n -平均气温 >5℃的月数 ;ti …     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Boron in forest trees and forest ecosystems

This review critically examines the role of boron (B) in forests in view of recent findings on B nutrition and the continuing occurrence of B deficiency. Many perceptions about the role of B in plants and its uptake and mobility have been altered since the last review on B in forest trees in 1990. Now there is evidence for a fundamental role of B in the formation of the pectic structure in primary cell walls in plants, and further roles in membrane function are being explored. In plants, channel-mediated B uptake, active B uptake and B uptake by mycorrhizas have been shown, B transporters have been identified, and B retranslocation has been shown. We explore these findings and their consequences on forest trees and on ecosystems that they dominate. Particular emphasis is placed on B retranslocation and B in mycorrhizal symbiosis, given their importance in trees.     

Survival and Growth of Picea abies Regeneration after Shelterwood Removal with Single- and Double-grip Harvester Systems

Three stands in Sweden were followed for 7 yrs to study the survival and growth of Norway spruce [Picea abies (L.) Karst.] regeneration after shelterwood removal with single- and double-grip harvester systems. The height of all seedlings within circular plots was recorded before and after final cutting. The tallest seedling and one randomly selected seedling on each circular plot were permanently marked and their annual height growth was measured each year during the period 1993-1999. No significant differences between single- and double-grip harvester systems were found with respect to their effects on regeneration density, survival or annual height growth. The annual height growth of the individual seedlings after shelterwood removal was significantly correlated with seedling height before shelterwood removal. Significant differences were found in annual height growth between seedlings with high and low vitality. Logging damage did not affect the annual height growth. Several practical conclusions were drawn. First, the choice of harvester system does not affect seedling height growth or survival after shelterwood removal. Secondly, the removal of a 200 m³ shelterwood with 200 stems ha^-1 does not seem to constitute a serious problem for seedling survival and growth. Finally, estimated vitality and seedling height both seem to be fairly good predictors of postrelease survival and growth.     

Development of Pinus sylvestris Main Stems Following Three Different Precommercial Thinning Methods in a Mixed Stand

Reducing competition by point cleaning may be an attractive alternative to conventional precommercial thinning in forestry. In this study, survival and development of main stems of Scots pine (Pinus sylvestris L.) following point cleaning were examined in a mixed stand of mainly Scots pine and birch (Betula pendula Roth and Betula pubescens Ehrh.) in northern Sweden. Treatments studied were: no precommercial thinning, conventional precommercial thinning, point cleaning of all secondary stems, and point cleaning of only the secondary stems that were higher than the main stem, within a radius of 0.8 m from the main stem, respectively. A randomised complete block design with three replicates was used. Measurements taken 13 growing seasons after these treatments showed that conventional precommercial thinning was the best treatment for retaining Scots pines as main stems. However, conventional precommercial thinning resulted in the poorest timber quality of the remaining Scots pines in terms of stem taper, thickest branch diameter and relative live crown height. In conclusion, point cleaning has to be followed by a complementary cleaning operation if the objective is to retain Scots pines as main stems in such mixed stands.