杨树红心病危害的调查研究

杨树红心病是分布广泛、危害严重的一种病害,几乎所有杨树品种都会遭侵染,成年树病株率达100%,变色比率15.65%~50.70%。从当年生扦插苗到成年树均能发生,红心病主要发生在主干的髓心和木质部。该病的严重程度与栽植的立地条件有关,在低洼湿地栽植的杨树其变色程度严重,且随树龄的增加而加剧,生长速度快的杨树,危害程度大。杨树品种不同,危害程度不同,品种之间存在着显著差异。     

杨树红心病的研究

2006-2008年对杨树红心病进行调查、病原菌分离培养和致病性实验。结果表明,杨树红心病是一种为害严重的病害,成年树病株率达100%,变色率为15%-95%。砖红镰刀菌和接骨木镰刀菌是引起杨树红心病的病原菌,该病的发生与栽植立地条件、杨树品种有关。     

红栀子褐斑病的发生与防治研究

红栀子褐斑病Phyllosticta spp．主要危害植株的中、下部叶片形成褐斑，严重时叶片枯萎脱落。病菌以菌丝体或分生孢子器在病落叶或病叶上越冬，每年3—11月病害都可发生。气温在25℃以上，病害发生严重。50％多菌灵WP1000倍，30％利德隆悬浮剂2500倍对红栀子褐斑病有较好的防治效果，连续施药3次后防治效果90％以上。     

枣疯病及其防治

枣疯病是枣树的毁灭性病害。国外韩国、印度有发生;国内山东、河北两省发生严重。我省枣区该病早有发生,近年来蔓延危害趋于严重,尤其在清涧、延川两县,发生蔓延面积最大。据调查估计,两县感病株率达5%以上的枣林面积约有660多公顷,感病株率达30%的枣林约有100ha。由于枣疯病的危害,红枣每年减产在100万 kg 左右,造成经济损失在200万元以上。枣疯病发病株数一般每年递增1%～3%,局部严重地区递增在10%     

天然红松林与人工红松林大型真菌生物多样性及主要病害变化规律

对天然红松林与人工红松林大型真菌及发生的主要病害进行了调查研究。天然红松林内大型真菌为211种,林木病害主要以立木腐朽菌危害最为严重;人工红松林大型真菌种类为47种,林木病害主要以枝干和叶类病害危害最为严重。单一树种的人工红松林直接影响到大型真菌种类的减少,又形成了适合病原真菌流行的高密度和大面积的适宜寄主,从而造成侵染性病害的严重发生。这说明,真菌生物多样性是随着林内植物多样性的变化而改变的。     

应用Na2CO3液防治杨树水泡溃疡病

杨树水泡溃疡病（Ｂｏｔｒｙｏｓｐｈａｅｒｉａｒｉｂｉｓ）是杨树最常见、危害较重的一种病害。朝阳县平均每年发生面积为４０００ｈｍ２，发生病株率为１９％～３５％。不仅严重地影响了树木的正常生长发育，甚至有的造成全株干枯死亡或被侵染后变成毫无保留价值的Ⅲ、...     

紫溪山樱桃冠瘿病传播途径调查与防治技术研究

楚雄市紫溪山樱桃栽培历史悠久,近几年栽培面积不断扩大,随着产业发展,已成为当地村民重要经济收入之一,但樱桃冠瘿病害也随之发生。2016—2018年连续3年对紫溪山樱桃冠瘿病危害及其传播途径进行调查。结果表明,冠瘿病主要危害樱桃的树干和枝条,危害特征明显,危害程度逐年加重,且发病率高,传播速度快。土壤和病株冠瘿病病菌主要通过雨水、灌溉近距离传播和修剪扩散传播,此外,冠瘿病的病菌还通过红颈天牛等蛀干昆虫进行远距离传播。文中提出土壤消毒、苗木处理、病株除治、红颈天牛防治等樱桃冠瘿病的防治技术措施。     

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。     

红棕象甲的初步调查研究

红棕象甲是椰子树主要害虫之一，此虫在海南岛分布于琼山、定安、文昌、琼海、万宁、乐东、儋州等地；成、幼虫为害椰予树叶柄及茎顶，严重为害时可使椰子树致死，据调查此虫对椰子树为害率高达84％，叮通过捡疫、化学防治等措施加以防治。     

杨树烂皮病发病规律及防治方法

对白石山林业局杨树烂皮病多年跟踪调查发现,病害的发生与杨树的树种、林龄、环境等因素有直接关系,不同林龄的杨树感病株率不同,树木越大,感病株率越小,树木越小,感病株率越大,杨树幼林平均感病株率为3.0%,杨树新植林平均感病株率为45.0%;杨树树种不同感病株率也不同,生长速度快的比生长速度慢的感病株率大,在新植林中,大青...     

Relationship between the incidence of pine wilt disease and the drainage area

We examined the relationship between the incidence of pine wilt disease and moisture conditions in the stand level ofPinus densiflora Sieb. et Zucc. forests in the warm-temperate zone of the western part of Japan. For this analysis, pine trees killed by pine wilt disease were distinguished from the suppressed trees by their position in the layer of the pine forest stand. The drainage area, which is small in the upper part and large in the lower part of the slope, was adopted for representing the moisture conditions in the soil of the slope. The percentage of the pine trees killed by pine wilt disease increased as the size of the drainage area increased. This result suggested that the incidence of pine wilt disease tended to be high in areas with moist conditions. Pine trees attacked by the pinewood nematode die from extensive water deficit due to tracheid cavitations. Pine wilt disease mainly emerges in the summer when the soil water conditions become especially severe, and the radical water stress is thought to accelerate the disease. It was assumed that pine trees in the plots with the small drainage area resisted the influence of the attack of the pinewood nematode because pine trees in the plots with the small drainage area encountered long-term water stress and acquired drought tolerance. Pine trees in the plots with the large drainage area were presumed to be well established in the moist conditions and not to have acquired drought tolerance. The drought tolerance of pine trees was thought to be an important factor in resistance to pine wilt disease.     

Localized within‐ and between‐tree variation in nematode distribution during latent state of pine wilt disease makes the disease status cryptic

The pinewood nematode (PWN), Bursaphelenchus xylophilus, is the causal agent of pine wilt disease, an epidemic disease that has severely damaged pine forests in East Asia. The disease has spread to northern areas in Asia and parts of Europe. To prevent disease spread as the forefront of damage prevention, a better understanding of infection status is highly important. Not all infected trees show disease symptoms, and such asymptomatic PWN‐carrying trees are likely to be overlooked and can become a pathogen reservoir. To elucidate PWN infection status in asymptomatic trees, we performed PWN inspection of branches and trunks in 21 test trees in two different conditions: trees that had experienced PWN inoculation and those with suspected PWN infection that had experienced transient foliage discoloration. We detected PWNs in eight test trees (38%) and in 13 (1.5%) of a total of 843 samples. The difference in these percentages suggests that nematode inhabitation was highly localized within the trees, possibly owing to the restricted migration of PWNs. Our data demonstrated that trees that were once weakened but recovered their vigour can persist, as the asymptomatic carriers, in the forest. The implications for disease control are also discussed.     

The impact of Phytophthora disease on riparian populations of common alder (Alnus glutinosa) in southern Britain

In 1994 a survey was established to obtain information on Phytophthora disease of common alder (Alnus glutinosa) on the riverbanks of southern England and east Wales. Within an area of 70 000 km² 63 observation plots were set up on stretches of river over 8 m wide. Average alder densities varied widely in different parts of the survey area; from 0.7 to 22.2 trees per 100 m of river. From the density figures and data on the total length of rivers over 8 m wide within the survey area, it was estimated that there were approximately 585 000 alder trees growing on the banks of such rivers. In 1994 3.9% of the trees showed crown symptoms of Phytophthora disease, and an additional 1.2% of trees were dead, although not all of these had been killed by Phytophthora. The disease occurred widely through the survey area with an indication that the highest percentage of affected trees was to be found in the south-east of England. Subsequent surveys showed that the combined percentage of symptomatic and dead trees rose to 6.0% in 1995 and to 7.9% in 1996. In the latter year, for an alder population of 585 000 trees, this would correspond to 32 800 symptomatic and 13 500 dead trees. The percentage of trees showing symptoms was seven times as high in trees growing within 1 m of the riverbank as in trees growing between 1 and 10 m of the bank. An examination of the relationships between disease incidence and various indices of water pollution revealed a positive association with total oxidized nitrogen. These results are discussed in relation to the biology and possible origin of the disease.     

Evidence for the occurrence of induced resistance to pitch canker,caused by Gibberella circinata (anamorph Fusarium circinatum), in populations of Pinus radiata

Pitch canker, caused by Gibberella circinata, was discovered in California in 1986. Although initially quite damaging to Monterey pines (Pinus radiata), the severity of pitch canker has moderated in areas where the disease was first observed and some trees appear to have recovered completely. The absence of symptoms on trees that were once severely affected implies they have become more resistant to the disease. Experimental work has shown that P. radiata can manifest systemic induced resistance (SIR) in response to infection by the pitch canker pathogen and observations of disease remission may indicate that SIR is operative under natural conditions as well. As a test of this hypothesis, the susceptibility of trees in remission was assessed by inoculating them with G. circinata and recording the extent of lesion development. In addition, randomly selected trees in areas that differed in residence time of pitch canker were inoculated to determine if trees with a longer period of exposure to the pathogen were more resistant to the disease. The results of these tests showed that 89% of trees observed to be in remission sustained very limited lesion development, consistent with resistance to pitch canker. Furthermore, trees in areas where pitch canker was well established tended to be more resistant than trees in areas where the disease was of more recent occurrence. In sum, these findings support the view that SIR occurs in P. radiata and is contributing to a moderation of the impact of pitch canker under natural conditions.     

Effect of resin‐top disease caused by Peridermium pini on the volume and value of Pinus sylvestris saw timber and pulpwood

The role of the resin‐top disease caused by Peridermium pini in volume and value losses to Scots pine (Pinus sylvestris L.) was surveyed in two heavily infected stands in northern Finland. Of the Scots pines, 26% were infected by the disease. Peridermium pini caused 2% volume losses to saw timber trees and 3% volume losses to pulpwood trees in the stem‐lesion class and 10% and 14% in the dead‐top class, respectively. The disease caused saw timber volume losses to saw timber trees of 34% and 22% in the stem‐lesion and dead‐top class, respectively. However, saw timber volume losses increased the pulpwood volume in both disease classes. The disease reduced the marketing value of saw timber trees and pulpwood trees by 18% and 3% in the stem‐lesion class and by 15% and 14% in the dead‐top class.     

The interaction between competition in interior Douglas-fir plantations and disease caused by Armillaria ostoyae in British Columbia

Interior Douglas-fir trees in plantations were assessed for size differences related to the level of diseased neighbours infected with Armillaria ostoyae. The four Douglas-fir stands studied ranged from 25- to 34-year-old, and represented the oldest accessible planted stands in the Interior Cedar Hemlock (ICH) ecosystem in British Columbia. Twenty-three to 25, 10-m radius plots were established in each stand. The spatial coordinates, total height, and diameter at breast height of all live and dead trees in the plots were recorded. Subject trees whose competitors were contained in the 10-m radius plots were also identified. Trees were pulled out of the soil using a mechanical excavator and the root systems were surveyed for evidence of infection by A. ostoyae. Stem disks were taken from each tree at 1.3 m above the ground for a determination of basal area. Increasing proportion of diseased trees in the plots resulted in less total plot basal area, but did not affect the mean basal area or height. Individual subject tree basal area was negatively related to the level of disease in surrounding competitors, opposite to expectations; however, diseased subject trees had reduced height and basal area compared to disease-free subject trees. Increasing competition reduced both the height and basal area of the trees, while regular distribution of all trees increased both total and mean plot basal area but not height. Disease incidence at the plot level and in individual subject trees was mainly affected by the neighbourhood conditions in which it grew, and was also related to disease intensity in the tree root systems. Although disease may alter resource partitioning among trees, the utilization of these resources is mostly limited by the increasing disease incidence as the stands age, the higher probability of larger trees being diseased with time, the occurrence of dead trees in clumps, and the high probability that dead trees will eventually infect live neighbours. The widespread belowground incidence of A. ostoyae in the ICH, its rapid colonization of stumps, and its wide host range can reduce site potential in managed stands.     

Relationship of site and stand characteristics to Armillaria root disease incidence on ponderosa pine in the Black Hills,South Dakota

Ponderosa pine (Pinus ponderosa) in the Black Hills National Forest, SD, USA, was surveyed for Armillaria root disease (ARD). The root pathogen Armillaria ostoyae occurred on ponderosa pine seedlings, saplings, pole‐size trees and large‐diameter trees. The mean incidence of aboveground disease symptoms by stem count was low (0.2%), but in certain areas, the incidence was higher, affecting the regeneration success and tree longevity. Symptomatic ponderosa pine were in areas characterized by having higher elevation, greater annual precipitation, more seedlings, bigger large‐diameter trees and greater odds of past harvesting activity than in areas without root disease. Stump density was positively spatially correlated with root disease incidence. No particular soil type was related to disease occurrence; though, in areas with symptomatic trees, soil available water holding capacity (AWC) was greater and soil permeability was less where root disease was present. Spatial analysis confirmed the relationships found in linear correlations, with soil AWC and stump density positively and soil permeability negatively correlated with per cent infected stems ha^?1 and basal area infected.     

橡胶树AM菌根研究进展

橡胶是四大工业原料之一 ,在交通、军用工业中尤为重要。其中天然橡胶的主要来源是巴西橡胶树 (H evea brasiliensis Muell. Arg.) ,它在我国南方热带地区广为栽培 ,是重要的经济树种和用材树种 ,因而是工业与民用的重要资源。已有研究证实 :橡胶树根系可以形成 AM菌根 (arbuscular mycorrhiza)。AM菌根是广泛分布的一类内生菌根 ,能够促进宿主植物吸收土壤中的养分 ,增强宿主的抗逆性 ,有利于植物生长。近 30 a来 ,国外一些学者对橡胶树菌根真菌的资源与分布 ,菌根真菌对苗木营养和生长效应以及提高苗木抗逆性方面进行了研究。而国内尚…     

Dutch elm disease has currently a low incidence on wych elm in Norway

A rapid increase in the frequency of Dutch elm disease (DED), a wilting disease of elm trees caused by bark‐beetle vectored fungi, was observed in the early 1990s on several wych elm stands around Oslofjord, southern Norway. To examine the current status of the disease and its impacts on elm population, disease frequency and size distribution of elms were recorded at four locations. Northern parts of Lier, a municipality most affected by DED in Norway 15 years ago, showed in the survey season 4% disease frequency, whereas 13.8% of trees were dead, the dead trees having accumulated over several years in the unmanaged stands. In southern parts of the municipality the mean disease and death percentages were 1.9 and 2.4%. Compatible with their low disease incidence in early 1990s, the other two areas now examined, municipality of Larvik and district of Grenland, showed comparably low frequency of DED. Northern part of Lier showed significantly higher overall density of elm trees per hectare than the other examined areas, and also the small elms below 5 cm in d.b.h. were most frequent in this region. In contrast, the density of large trees was lower in northern Lier than in the other examined areas. These data suggest that regeneration of the tree is not prohibited owing to the disease but that the large trees have been locally reduced in frequency as a result of DED. The superior general density of elm trees in northern Lier, owing to the exceptionally rich soil in the warm southern slopes of the region,> may have contributed to the rapid increase of DED in the area 15 years ago and to the subsequent settlement of the disease outbreak as a chronic stage.     

杨树溃疡病防治技术的研究

杨树溃疡病(Dothiorella gregaria)是杨树重要枝干病害,可在定植后的幼树主干上形成大型溃疡斑,常导致幼树死亡。1987年辽宁省康平、法库、昌图三县因此病损失的幼树近200万株,仅苗木费一项经济损失达70万元左右。1988年铁岭市发病面积近5万亩,损失幼树132万余株,经济损失达42万余元。为尽早控制此病危害,我们于1988～1989年在昌图县红