四霉素对茶藨子葡萄座腔菌Botryosphaeria ribis室内毒力测定及其田间防效试验

为确定四霉素对杨树溃疡病的防治效果,采用菌丝生长速率法测定四霉素水剂对茶藨子葡萄座腔菌Botryosphaeria ribis的室内毒力,采用刮治喷涂法对茶藨子葡萄座腔菌引起的杨树溃疡病进行田间应用效果研究。试验结果表明,四霉素对茶藨子葡萄座腔菌的EC_(50)和EC_(90)分别为114.82 a.i.mg/L、389.05 a.i.mg/L,对茶藨子葡萄座腔菌具有较好的抑菌效果,优于对照药剂多抗霉素。田间防效试验结果表明,刮治喷涂0.3%四霉素水剂可以有效防治真菌病原茶藨子葡萄座腔菌导致的杨树溃疡病,其有效成分浓度为60～150 a.i.mg/L时,田间防效达68.25%～82.41%,与室内毒力测定结果相符。     

三种生物源农药对桃树蚜虫的防治效果研究

为筛选生产上防治桃树蚜虫的生物源农药,开展了1.5%除虫菊素水剂、0.3%苦参碱水剂和5%桉油精可溶液剂对桃树蚜虫的田间防效试验。结果表明,3种生物源农药中以0.3%苦参碱水剂防治效果最好,药后1 d防效为70.12%,药后7 d防效为91.96%,与对照药剂70% 吡虫啉水分散粒剂防效相当,具有较好的速效性和持效性。苦参碱对桃树安全,是防治桃蚜的理想药剂,生产上推荐使用浓度为1 000倍液。     

四霉素与噁霉灵混配制剂对水稻立枯病的防治效果

水稻是我国第一大粮食作物,为有效防治水稻立枯病并减少化学农药的使用量,进行了农药混配制剂的筛选。通过室内不同比例的噁霉灵与四霉素混配抑菌试验及田间防治试验,筛选出能有效防治水稻立枯病的四霉素与噁霉灵混配制剂,四霉素与噁霉灵有效成分比例为0.152.5,共毒系数为139.03,增效作用明显;当田间使用剂量为33.13~39.75 g/hm2时,田间防效达到73.30%。试验结果表明,四霉素与噁霉灵按一定比例混配可以有效防治水稻立枯病,有效减少化学农药的使用量。     

论东北地区杨树溃疡病的防治措施

东北地区具有典型代表的病害是杨树溃疡病,轻则会形成枯梢、重则会导致杨树的整株死亡、甚至会导致杨树林的成片枯死。本文结合东北地区杨树培育和养护工作的具体情况,将杨树溃疡病进行了类型上的划分,分析了水泡型杨树溃疡病、大斑型杨树溃疡病、烂皮型杨树溃疡病和细菌型杨树溃疡病的发病机理和发病表现,并在此基础上,提供了防范水泡型杨树溃疡病、大斑型杨树溃疡病、烂皮型杨树溃疡病和细菌型杨树溃疡病的技术措施。     

杀虫剂不同处理对二化螟为害、防治效果及水稻产量的影响

近年来,二化螟发生出现各代均偏重或大发生的新特点。为探索杀虫剂防治二化螟的新策略,采用田间小区试验在早晚稻田中分别研究5%氟虫腈加25%灭.水胺的不同施药时期和次数对二化螟幼虫的为害和防治效果及对水稻产量的影响。在试验地,二化螟第1和第2代发生在早稻田,第3和第4代发生在晚稻田。试验结果表明,在第1和第3代二化螟幼虫孵化高峰施药1次、隔10d再施药1次对早稻田和晚稻田的幼虫防效显著,分别达到了92.4%和92.6%。在早、晚稻田分别发生的第1和第3代2龄幼虫高峰期施药1次、同时在次代孵化高峰期再施药1次,均可显著降低虫伤株率和白穗株率,提高保穗效果,并显著提高单位面积上的水稻产量(3.98%~4.20%)。因此,对第1至第4代二化螟幼虫均进行1次药剂防治是二化螟各代均大发生的新形势下的防治策略。     

生防链霉菌SSD49的绿色荧光蛋白标记及其在毛白杨组培苗中的定殖

杨树溃疡病是中国杨树人工林重大生物灾害之一,采用生物防治的方法控制杨树溃疡病是持续有效的手段。为了获取能够高效定殖并对杨树溃疡病菌有良好生防效果的拮抗菌株,通过引入强启动子(erm Ep)构建了高表达绿色荧光蛋白(Green fluorescent protein,GFP)的重组质粒,进而通过接合实验将该质粒导入到链霉菌生防菌株SSD49,构建了绿色荧光蛋白标记菌株SSD49-p IJ8660Ep,利用荧光显微镜研究该生防菌在毛白杨组培苗中的定殖情况。结果表明,SSD49标记绿色荧光蛋白后没有影响其对杨树溃疡病病原菌的抑菌活性,标记菌株能够定殖于毛白杨组培苗的茎和叶中。成功将杨树溃疡病生防菌株SSD49进行了绿色荧光蛋白标记,并且该菌株在毛白杨组培苗中有一定的定殖能力。     

从杨树菇中开发新型食品防腐剂的初步研究

本实验室通过对14株食用真菌的抑菌试验筛选,发现杨树菇具有极强的抑菌作用,且抑菌谱广,可以有效抑制细菌、酵母和部分霉菌。与不同浓度(0.05%、0.1%、0.2%、0.3% g/ml)山梨酸、苯甲酸抑菌能力相比,抑菌效果更为明显。以金黄色葡萄球菌为指示菌研究了其最适发酵条件及有效成分的热稳定性,结果表明:杨树菇的发酵周期为7-9d,发酵温度25℃,发酵的起始pH 6.0~7.0,发酵液装量为80~140 ml/500 ml三角瓶,接种量10%~15%(v/v);发酵液浓缩液经121℃、30 min湿热灭菌处理后仍具有很强的抑菌活性。杨树菇是一种具有开发前途的食用真菌。     

不同木霉菌对火龙果溃疡菌的拮抗效果研究

火龙果溃疡病是危害火龙果的重要病害之一.为有效开展火龙果溃疡病的生物防治,本研究比较了17种木霉菌的菌丝生长速率、产孢量,并通过对峙抑制试验和盆栽试验等比较不同木霉菌对火龙果溃疡病的抑制作用,从中筛选出了木霉菌KN-28,其抗生效果最强,其无菌发酵液对火龙果溃疡菌的抑制率高达92.9%,盆栽试验防效可达到59.07%～70.11%.综上所述,木霉菌KN-28防治火龙果溃疡病的潜力巨大,有望作为火龙果的生防目的菌株.     

666对中稻田二代二化螟幼虫的防治试验

在我国南方早中稻地区,用666防治一代二化螟的效果很好。但用于防治二代二化螟的效果往往不够稳定。为此,我们在中籼稻田进行了以下试验: 在二代螟卵孵化基本结束、田间有各龄幼虫时,用666处理稻田(用6％666粉剂),试验分不同用药量及不同施药方法两组处理,共11个小区,小区面积0.3亩,施药后3天检查田间各龄幼虫死亡率,结果如表1     

杨树截干上白杨透翅蛾的危害及防治

在内蒙古巴彦淖尔市杨树人工防护林区,采用杨树高枝截干是防治光肩星天牛Anoplophora glabripennis(Motschulsky)的有效手段之一。但在当年春季杨树截干上留下的机械伤口及新萌发枝条,为白杨透翅蛾Paranthrene tabaniformis(Rott.)的入侵提供了有利条件。白杨透翅蛾在1~3年的截干上发生密度较高,严重时影响到新萌发枝干的生长甚至死亡。2007年5月调查发现,在杨树截干上白杨透翅蛾的有虫株率达到89·17%,平均虫口密度达到(3·40±0·21)头/株,远远超过了0·3头/株的最低防治标准。最后,结合当地杨树人工防护林网的特殊环境条件,提出了针对性的防治措施。     

杨树溃疡病生防菌株N6-34抗菌活性物质的分离纯化与结构鉴定

【背景】杨树溃疡病是一种主要由葡萄座腔菌引起的杨树枝干病害,危害严重。前期从杨树中分离到一株内生拮抗细菌N6-34,研究表明该菌株拮抗效果好,对多种植物病原菌均有较强的拮抗作用。【目的】对拮抗细菌N6-34产生的抗菌活性物质进行分离纯化,并鉴定了活性物质组分的结构。【方法】通过硫酸铵盐析、甲醇抽提、分子筛、高效液相色谱等方法分离纯化N6-34菌株的抗菌活性物质,并对其进行结构鉴定。【结果】N6-34菌株发酵液经多步分离纯化,共获得14个组分,其中有13个组分具有抗菌活性,经一级质谱分析,获得了13种抗菌活性组分的分子量;经二级质谱分析,将13种抗菌活性物质鉴定为Fengycin A或Fengycin B的同系物或同分异构体。【结论】从N6-34菌株发酵液中分离获得了13种抗菌成分,为杨树溃疡病的生物防治提供了理论依据。     

Poplar stem blister canker and its control strategies by plant extracts

Stem blister canker is a serious stem disease in the Populus genus in China. The pathogen was confirmed as Botryosphaeria dothidea (Moug. ex Fr.) Ces. et de Not. based on its morphological, pathological and molecular features. Seven selected plant species Artemisia annua, Gleditsia sinensis, Lonicera japonica, Macleaya cordata, Phyllodendron chinense, Polygonum cuspidatum and Scutellaria baicalensis, belonging to different families from China, were extracted with the solvent 95% (v/v) ethanol to yield ethanol extracts which were used to evaluate their antifungal activity against poplar stem canker pathogen by a mycelial radial growth inhibition test. Of them, the extracts of M. cordata, P. cuspidatum and S. baicalensis showed stronger antifungal activity, the median inhibitory concentration (IC₅₀) was 0.3125, 1.0219 and 0.9675 mg ml⁻¹ separately. The control effect of extracts of M. cordata, P. cuspidatum and S. baicalensis on poplar stem canker disease was between 62% and 85%. The inhibitory effect of the extracts indicated the importance of some plant species as possible natural source of fungicidal material.     

Bark morphological and chemical features are differentially correlated with disease resistance and yield in hybrid poplar taxa

In the southeastern United States, the establishment of short-rotation intensively cultured plantations of hybrid poplar has been hindered by its susceptibility to stem cankers. We evaluated the tradeoffs between biomass yield and disease tolerance in hybrid poplar genotypes belonging to P. deltoides × P. maximowiczii (DM), P. deltoides × P. nigra (DN), P. trichocarpa × P. maximowiczii (TM), and P. deltoides × P. deltoides (DD) taxa. We hypothesized that canker resistant genotypes will have thicker bark but bark thickness and biomass yield will be negatively correlated. After two growing seasons, the DD genotypes developed thicker bark compared to the genotypes of other taxa and bark thickness was not correlated with biomass yield in the DD genotypes (R² = 0.002). However, in the TM, DM, and DN genotypes, bark thickness was negatively correlated with biomass yield (R² = 0.33–0.77). Disease incidence studies revealed that the DM genotypes were most susceptible to canker whereas no disease was detected in DD genotypes. Furthermore, bark analysis conducted by Fourier transform infrared spectroscopy coupled with multivariate analysis showed that that DD genotypes to be chemically separate from the three hybrid genotypes and that bark chemistry was correlated with canker disease incidence. Taken together, these results reveal that it is possible to generate hybrid poplar genotypes with thicker bark, disease resistance, and higher biomass yields. This insight should guide further efforts to develop genetically improved hybrid poplar genotypes, both in terms of biomass yield and disease tolerance, for cultivation in the southeastern United States. Hybrid poplar cultivation in southeastern United States is hindered by its susceptibility to stem cankers. We evaluated tradeoffs between yield and canker disease resistance in various hybrid poplar genotypes. After two growing seasons, the DD genotypes showed disease resistance and developed thicker bark that was chemically distinct from the other genotypes. Bark thickness was not correlated with yield in the DD genotypes but was negatively correlated with yield in the other genotypes. These results will guide the development of hybrid poplar genotypes that are both disease resistant and high yielding for cultivation in the southeastern United States.     

Isolation and characterization of a new Burkholderia pyrrocinia strain JK-SH007 as a potential biocontrol agent

Poplar canker is a kind of serious disease of poplar branches in China and all over the world. In China, the poplar canker is mainly caused by three pathogens of Cytospora chrysosperma, Phomopsis macrospora and Fusicoccum aesculi, which is hard to control. A collection of 1,013 bacterial isolates obtained from the poplar stems in 9 regions of China. Of all the strains tested, 13 bacterial isolates inhibiting three pathogens (C. chrysosperma, P. macrospora and F. aesculi) growth were selected, whose inhibition zone width were more than 15 mm. Strain JK-SH007 exhibited the most obvious antagonistic activity. Besides, this strain also produced extracellular hydrolytic enzymes (β-1, 3-glucanases, proteases and chitinases). This bacterium had no pathogenicity and was identified as Burkholderia cepacia complex (Bcc) genomovar IX: B. pyrrocinia by the Biolog identification system combined with 16S rDNA and recA gene sequence analysis and morphological, physiological and biochemical methods characteristics. B. pyrrocinia JK-SH007 exhibited the highest biocontrol and colonization capabilities. After 3 months, plant height and ground diameter in poplar seedlings inoculated with JK-SH007 were significantly (P < 0.05) higher than in control (non-inoculated) plants. The selected B. cepacia isolate colonized poplar stems and leaves endophytically, promoting plant growth and suppressing pathogenic activities of C. chrysosperma, P. macrospora and F. aesculi on seedling of poplar. This is one of the few reports dealing with isolation and characterization of B. cepacia strains with biocontrol activity against the poplar canker. The endophytic isolate also has the potential to perform as plant growth promoter.     

拮抗植物病原真菌链霉菌菌株ZH-356的鉴定及其生防评价

[目的]对实验室分离到的菌株ZH-356进行鉴定并评价其对植物病原真菌的生物防治效果,为研发针对植物真菌病害的生防菌剂提供理论指导。[方法]通过平板对峙法确定菌株ZH-356抗菌谱,并通过16S rRNA基因序列分析确定其种属,利用离体枝条的苹果树腐烂病菌感染预防试验和患腐烂病苹果树的防治试验评价其生防效果。[结果]菌株ZH-356鉴定为链霉菌属,与直丝紫链霉菌(Streptomyces rectiviolaceus)相似性最高,为99.71%。抗菌谱试验表明,菌株ZH-356对苹果树腐烂病菌、小麦赤霉病菌、小麦根腐病菌和番茄早疫病菌等多种植物病原真菌均具有较强的抑制作用,这种抑制作用可导致苹果树腐烂病菌菌丝变粗、交叉扭曲、分支变少且容易断裂。此外,ZH-356产生的抑菌活性物质对温度和酸碱度具有高度稳定性,并且该活性物质只存在于其胞内,只有当ZH-356遇到植物病原真菌时才会被分泌出来以抑制它们的生长。在离体枝条的苹果树腐烂病菌感染预防试验中,ZH-356对苹果树腐烂病防效可达94%以上,而在患腐烂病苹果树的防治试验中,ZH-356菌制剂对苹果树腐烂病的防效高达100%。[结论]链霉菌ZH-356抑菌谱广,对多种植物病原真菌均具有良好的拮抗活性,可作为防治植物真菌病害的生防菌株,为基于ZH-356菌株的生防菌剂的开发和防治苹果树腐烂病等植物真菌病害奠定了基础。     

Bacterial canker of poplar

Bacterial canker is a serious disease of poplar and it is important for commercial planting to select those clones of poplar which show resistance to the disease. In inoculation tests, natural bacterial slime and a pure bacterial suspension gave similar extent of invasion. A study of the life-cycle of the disease indicated the presence of inoculum and of potential infection courts throughout the growing season. It is suggested that the susceptibility of a poplar clone should be determined by assessment of both artificial inoculations and natural infection.     

STUDIES ON THE BACTERIAL DIE-BACK AND CANKER DISEASE OF POPLAR

Artificial freezing caused leaf necrosis and twig die-back but did not produce cracks or cankers on living branches of three varieties of poplar. Freezing increased the damage caused by a well-established infection of the bacterial die-back and canker but checked new lesions. Freezing prior to infection has no appreciable effect on the establishment of the disease.     

Cryptosphaeria Canker of Populus nigra Caused by Cryptosphaeria pullmanensis,a New Threat to Poplar Industry in Iran

Trunk diseases are potential threats to the poplar industry worldwide, including Iran. A survey on trunk diseases of Populus nigra in north‐western Iran revealed a new canker disease associated with dieback and decline of this host in West Azarbaijan Province of Iran. Wood samples were collected from poplar trees showing canker, dieback and decline symptoms and taken to the laboratory. A total of 173 fungal isolates were recovered from symptomatic tissues, of those 147 isolates had similar cultural and morphological features on potato dextrose agar. Based on a combination of morphological characteristics and phylogenetic inferences including DNA sequence data from the internal transcribed spacer regions (ITS1, 5.8S rDNA, and ITS2), all 147 isolates were identified as Cryptosphaeria pullmanensis. The remaining 26 isolates were identified as Cytospora chrysosperma. Pathogenicity of Cr. pullmanensis on two‐year‐old P. nigra and Populus alba saplings under glasshouse conditions confirmed that Cr. pullmanensis is pathogenic on P. nigra and P. alba. Cryptosphaeria pullmanensis is here reported from Iran causing Cryptosphaeria canker on poplar trees for the first time. However, its host range, the extent of geographical distribution and management strategies remain to be examined.