落叶松幼苗常见病虫害的防治措施

一、落叶松幼苗病害的防治 （一）立枯病落叶松立枯病是幼苗出土后发生的一种常见病害，持续时间较长，症状随着幼苗生长而变化，主要有4种类型。     

敌克松退菌特防治落叶松幼苗立枯病试验初报

立枯病是苗圃最常见的一种病害,严重地影响落叶松幼苗成活率,特别是立枯病中的芽腐和猝倒病,在播种后至幼苗出土40天左右危害严重,病菌浸染种子或幼芽,使种芽组织腐烂,不能出土,减少出苗数量;对于刚出土的幼苗,病菌浸染后成片倒伏死亡。为了培育优质壮苗,提高幼苗成活率,防止立枯病的发生或蔓延,根据林业厅营林局1987     

预防松苗立枯病的技术措施

落叶松、樟子松幼苗立枯病,发病幼苗死亡率很高,轻则造成苗木减产,重则造成苗木绝产。近几年,内蒙古大杨树地区一些苗圃这种病害时有发生,特别是大扬树林业局宜里林场苗圃,由于这种病害的危害,苗木产量一直上不去。预防松类幼苗立枯病,成了大杨树地区各苗圃的一项亟待     

综合防治松、杉苗立枯病

综合防治松、杉苗立枯病文／李接球立枯病又称幼苗猝倒病，在我国各地苗圃中均有发生，为害严重。其主要为害松、落叶松、杉等针叶树幼苗，在短期内引起苗木大量死亡。苗木得病后，倒而枯死者称猝倒病，死而不倒者称立枯病。根据幼苗立枯病的发生规律，应采取如下以育苗技...     

用D801防治落叶松播种幼苗立枯病效果调查

我县乡村苗圃在播种培育落叶松苗木生产过程中,为了防治落叶松播种幼苗立枯病,采用D801复方杀菌剂,分别进行了拌种防治和喷洒幼苗防治立枯病的试验,均收到较好效果。我们使用丹东纺织助剂化工厂生产的D801,系复方杀菌剂。D801是农用杀菌药物与多种微量元素复方的杀菌剂,其含量为25％。播种用的种子是二等长白落叶松,喷洒试验用的幼苗是生长初期的长白落叶松幼苗。     

综合防治松、杉苗木立枯病

立枯病又称幼苗猝倒病．在我国各地苗圊中均有发生，为害严重；其主要为害松、落叶松、杉等针叶树幼苗．在短期内引起苗木大量死亡。苗本得病后．倒而枯死者称猝倒病．死而不倒者称立枯病，根据幼苗立枯病的发生规律．应采取如下以育苗技术为主的综合防治：     

沙棘幼苗立枯病防治初探

通过对俄罗斯沙棘幼苗立枯病的综合防治,得出如下结论:1)立枯病预防重在土壤前期处理和种子处理;2)发现立枯病后可及时用高浓度的甲基托布津和多菌灵喷洒;3)幼苗期间控制水分,防止湿度较大;4)切忌选择前茬为蔬菜的土地进行沙棘育苗。     

苗圃幼苗立枯病防治

简要介绍了苗圃幼苗立枯病的症状、病原及防治方法。     

低温催芽预防落叶松苗立枯病

落叶松播种育苗的难题之一是立枯病,立枯病是由镰刀菌、丝核菌、棉腐菌等侵染幼苗所致。该病在6月中、下旬,地温20℃左右,幼苗出土不久,未生侧根时期发生。土壤粘重、浇水量大、前茬是菜或种子经高温催芽的幼苗发病率高。苗床中间较边缘处发病重。得过立枯病的苗床,呈块状或片状缺苗,往往减产20%～80%。我们在落叶松育苗中采用种子低温处理、早期播种、全光育苗、分段适时适量浇水等措施,有效地预防了立枯病的发生。1　种子低温处理用于播种的种子,精选后,在播前60d～70d混上两倍于种子的含水5%的中砂,装入箱内,上盖一层塑料布或草帘,放在1…     

白皮松幼苗立枯病流行因子分析

本文研究了土壤类型,土壤含水量、温度和湿度与白皮松幼苗立枯病流行的关系。结果表明：高含水量的耕作层土壤，高温、高湿和低温环境易引起立枯病的流行。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.