梨黑斑、黑星病的防治

黑斑病是由半知菌引起的病害。病原物以分生孢子及菌丝体在病枝梢、病芽、病果上越冬 ,次年从病组织上产生新的分生孢子 ,靠风雨传播。当孢子萌发后 ,通过梨树皮孔、气孔侵入或直接穿透寄主表皮侵入 ,引起初次侵染。然后在梨树整个生育期可多次产生新孢子进行侵染危害 ,形成重复侵染。1　病　　状梨黑斑病主要危害叶、果实、新梢。嫩叶最易受害 ,初期出现针头大小圆形黑色斑点 ,随后逐渐扩大成圆形或不规则直径为 1cm左右的病斑 ,病斑中心呈灰白色 ,边缘黑褐色 ,病斑多时可相互结合成凹陷的不规则大斑 ,在潮湿的条件下病斑表面形成黑霉物 ,…     

杜松赤枯病发生规律及防治技术研究

杜松赤枯病是 4年生以上杜松幼树的主要病害 ,在我省为害严重。研究表明 ,此病是由Alternariasp .和Phomasp .共同侵染所致。Alternariasp .以菌丝体和分生孢子越冬 ,Phomasp .以菌丝体和分生孢子器越冬。两种病原菌均通过皮孔、气孔和伤口侵入树体。两种病原菌的孢子均在5月下旬日平均气温达 16℃左右时开始放散 ,孢子的放散和萌发与空气温度的关系最为密切 ,雨季是孢子放散的高峰期。通过对 12种杀菌剂的室内药效测定 ,以及四种杀菌剂的室外防治试验 ,得出用 4 0 0～ 80 0倍液的多菌灵等连续防治 2～ 3年 ,可完全控制该病的发生和蔓延 ,防治方法简便易行 ,成本低廉 ,功省效宏     

花椒褐斑病的初步研究：Ⅱ,发病规律和防治试验

花椒褐斑病菌(Cereospora zanthoxyli)以菌丝体、子座和分生孢子在病落叶上越冬,初侵染始于5月上、中旬,生长季有多次再侵染发生。药剂防治应在5月下旬进行,50％甲基托布津500倍和50％多菌灵800倍喷雾效果较好,全年喷药3～4次可控制为害。     

山核桃枝枯病观察与研究

山核桃枝枯病(Melanconium oblongum Berk.)始发于8月中下旬,盛发于10～11月。病菌侵染1年生枝梢和2年生侧枝,并向下蔓延引起大枝条枯死。发病初期症状不明显,后期枝梢顶芽干缩,枝条内部变褐坏死,死皮上产生小黑点即为病菌的分生孢子盘。分生孢子在25℃下发芽率最高,低于10℃不能发芽。在pH3～11范围内都能发芽。病菌以菌丝体和分生孢子在病枯枝上过冬。     

垂柳烂皮病病原菌生物学特性及防治的研究

垂柳烂皮病是垂柳较为严重的病害，主要为害主干及枝条。近年来在呼市地区发生严重，１～４年生苗木感病最重，其病原菌为ＶａｌｓａｓａｌｉｃｉｎａＦｒ，无性阶段为ＣｙｔｏｓｐｏｒａｓａｌｉｃｉｓＲａｂ子囊孢子萌发温度５℃～４１℃，分生孢子萌发温度７℃～４２℃，两种孢子的萌发随温度的增大而升高，在散射光下萌发最好。该病发生的有利条件是低温高湿，保持树木生长旺盛是防治该病的主要条件，栽植时注意适地适树，良种壮苗，发生严重时可用２５％多菌灵５０倍液防治，防效可达９５％以上。     

杨树黑星病的初步研究

杨树黑星病ＦｕｓｉｃｌａｄｉｕｍｔｒｅｍｕｌａｅＦｒａｎｋ．以分生孢子侵染当年生新叶，６月出现症状，７月发病盛期，９月再发病高峰，以分生孢子或菌丝体在树枝梢或落叶上越冬。该病首先在立地条件差的地段发病，随树龄的增加病情减轻，与林分密度呈正相关。病害的发生、发展与６、９两月份的气温和降雨量呈正相关。根据气象因子可初步预测下年病情。     

芍药常见病害及防治

芍药红斑病芍药红斑病又称芍药褐斑病，是栽培芍药中最常见的重要病害。由枝孢霉菌引起，病原菌主要以菌丝体在病叶、病枝条、果壳等残体上越冬。翌年春季产生分生孢子，经气流和雨水传播到刚萌发的新叶上，当温度达20℃以上时，孢子开始萌发．引起初次浸染。一般下部叶片最先感病．感病叶片初期在叶背出现绿色针头状小点．     

哈密市葡萄主要病虫害发生规律及综合防治措施

哈密市葡萄的主要病害有白粉病、酸腐病、根癌病等;主要虫害有斑叶蝉、毛毡病等. 1 葡萄白粉病 1.1 发生规律 葡萄白粉病以菌丝体在病组织内或芽鳞下越冬,春季条件适宜时,产生分生孢子并借风力传播到当年生绿色组织上,萌发后直接侵入寄主,进行初次侵染.病菌可以在6℃～32℃的温度范围内生长,侵染和蔓延的适宜温度是20℃～2...     

阜新地区幼龄杨树腐烂病发病规律调查与综合防控

随着气候变暖等诸多自然环境的变化,杨树腐烂病(烂皮病)的发生呈上升势头,其危害造成的经济损失较严重。杨树主干部位和新生枝条是腐烂病主要侵染区域。腐烂病侵染杨树后呈两种形态,一种为干腐,另一种为(枯梢)枯枝。对于腐烂病的防治要坚持病前预防、农业防治、化学防治多管齐下的防治方法,会收到较好的效果。     

板栗褐缘叶枯病发病规律及防治试验

近几年在山东泰安等板栗Castanea mollissima产区发生一种新的叶部病害—板栗褐缘叶枯病Phpmopsis mollissima Y.Z.HUA S.X.JIANG。病原菌每年只侵染1次,侵染高峰期在8月份,以菌丝体和分生孢子在板栗病叶及冬芽上越冬。选用新型杀菌剂戊唑醇、氟硅唑和咪鲜胺防治该病,防治效果分别为93.4%,90.8%和72.4%。     

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.