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利用“有害生物危险性综合评价公式”对广西湿地松和马尾松林发生的萧氏松茎象Hylobitelus xiaoi
Zhang进行了危险性分析,R=1．911,属于接近高度危险的森林有害生物。发现阿维菌素和吡虫啉2种杀虫剂室内对萧氏松茎象接触毒性均较低,死亡率仅比对照高21．5％。林间药剂防治试验,平均防效仅为35．5％,表明化学防治不适宜作为调控的主要措施。采取人工抚育（疏伐）、化学除草、人工捕捉除治萧氏松茎象的生态调控和工程治理措施,从2004年到2006年,已经基本控制了萧氏松茎象在桂林湿地松上的蔓延危害。 相似文献
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应用白僵菌在1×10^5个孢子／ml、1×10^6个孢子／ml、1×10^7个孢子／ml、1×10^8个孢子／ml和1×10^9个孢子／ml 5个不同浓度对萧氏松茎象成虫进行毒力测定。其中以10^9个孢子／ml毒力最强,接种20d后,平均校正死亡率达100％,白僵率达95％,对萧氏松茎象成虫的致死和白僵速度最快,其LT50分别为8．39d和9．52d,10^8个孢子／ml次之,分别为9．30d和11．20d。各浓度对萧氏松茎象成虫的致死率和白僵率均随时间的增加而增加。在同一时间,致死率和白僵率均随孢子浓度的增加而增加。虽然10^9个孢子／ml和10^8个孢子／ml毒力强,但所需孢子量大,不适合应用于生产实践;10^7个孢子／ml毒力也很强,所需孢子量适中,因此较适合在生产实践推广应用。 相似文献
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Fatemeh Jafari Reza Mostowfizadeh-Ghalamfarsa Banafsheh Safaiefarahani Treena I. Burgess 《Plant pathology》2020,69(7):1281-1290
In recent years several interspecific hybrids have been reported in the plant pathogenic oomycete genus Phytophthora. Due to the large genotypic and phenotypic changes, these hybrids might have broader or more limited host ranges compared with their parental species. It is crucial to understand the host range of Phytophthora hybrids to minimize the economic losses caused by their infection. The potential host range of four hybrids belonging to Clade 8a of the Phytophthora phylogenetic tree was investigated in this study. Thirty species of herbaceous plants as well as eight species of woody plants were inoculated and monitored for any symptom of infection. In addition, the detached twigs of 32 tree species, fruits of six plant species, tubers of potato, and roots of carrot and sugar beet were investigated for susceptibility to these hybrids. Almost all hybrids caused severe rot on all tested fruits, tubers, and roots, although different isolates showed different pathogenicity on detached tree twigs. All hybrids tested had a different host range compared with their parental species: they were able to infect plants outside the host range of their parents, infect hosts of both parental species, although these parents did not have overlapping hosts, or, in some cases, they were not able to infect hosts infected by the parents. 相似文献
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ABSTRACT Sources of inoculum were investigated for dominant hosts of Phytophthora ramorum in a redwood forest. Infected trunks, twigs, and/or leaves of bay laurel (Umbellularia californica), tanoak (Lithocarpus densiflorus), and redwood (Sequoia sempervirens) were tested in the laboratory for sporangia production. Sporangia occurred on all plant tissues with the highest percentage on bay laurel leaves and tanoak twigs. To further compare these two species, field measurements of inoculum production and infection were conducted during the rainy seasons of 2003-04 and 2004-05. Inoculum levels in throughfall rainwater and from individual infections were significantly higher for bay laurel as opposed to tanoak for both seasons. Both measurements of inoculum production from bay laurel were significantly greater during 2004-05 when rainfall extended longer into the spring, while inoculum quantities for tanoak were not significantly different between the 2 years. Tanoak twigs were more likely to be infected than bay laurel leaves in 2003-04, and equally likely to be infected in 2004-05. These results indicate that the majority of P. ramorum inoculum in redwood forest is produced from infections on bay laurel leaves. Years with extended rains pose an elevated risk for tanoak because inoculum levels are higher and infectious periods continue into late spring. 相似文献
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梨和苹果腐烂病菌不同培养表型菌株的致病性分析 总被引：3，自引：0，他引：3
The pathogenicity of three strains (F-SD-8, F-BJ-2c-2 and F-HN-2a-1) of Valsa mali var. pyri causing pear canker and one strain (F-SX-A6) of V. mali var. mali causing apple canker in China were comparatively tested by wound inoculation on in vitro twigs of pear, apple and some other woody plants, and in vivo twigs of pear. Significant pathogenicity differentiation was detected in V. mali var. pyri. Generally strains F-SD-8 and F-BJ-2c-2 were highly pathogenic on pear although their culturing characteristics differed greatly. The strain F-SX-A6 was more aggressive on apple than on pear, and the strain F-HN-2a-1 showed significant lower pathogenicity on ten pear cultivars and other seven species of woody plants. Our results confirmed that two variants of V. mali had host preference and were also aggressive to crabapple, apricot, and peach besides apple and pear. Meanwhile, strains F-SD-8 and F-BJ-2c-2 could induce the formation of pycnidia on in vivo twigs of pear, which was not observed on in vivo twigs inoculated with F-HN-2a-1 and F-SX-A6. 相似文献
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The effectiveness of seeding introduced species, with or without straw mulching, was tested as a measure of post-fire erosion control in gypsiferous (Xeric Haplogypsid) and calcareous soils (Xeric Torriorthent) in Central Ebro Valley (NE-Spain). Paired control, seeding, and combined seeding and mulching plots were established in four replicated plots for each soil tested. Seeding rate was 30 g m -2 and straw mulch was applied at 100 g m -2 in each plot. Plant projective cover (total and specific), plant biomass, bare soil cover and sediment yield were determined over a 2-year period. During the first year of sampling, species introduced by seeding increased plant cover (about 30%) without significant differences observed between soils. Plant cover was similar in seeding-only and seeding-mulching treatments, although the latter treatment significantly enhanced plant weight. During the second year these differences disappeared because species introduced by seeding practically did not survive. So, the introduced herbs did not interfere with native plants. Bare soil cover remained significantly lower in treated plots than on the control plots for both soils during both years of sampling. In the second year, the reduction of bare soil was attributed to both the straw mulch and litter from the seeding species. Soil protection was significantly higher in calcareous soils than in gypsiferous soils which is related to their physical and chemical properties. Cumulative sediment yield decreased significantly over time with both treatments on both soils. Soil losses from control plots were three times higher than seeding plots and 3.3 times higher than from seeding and mulching plots in gypsiferous soils. Soil losses from control plots were two times higher than from seeding plots and 2.7 times higher than the combined seeding and mulching plots in the calcareous soils. Cumulative soil loss was higher from the gypsiferous soils than from the calcareous soils due to the lower plant cover. 相似文献
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子午岭主要森林类型土壤种子库研究 总被引：14，自引：0，他引：14
对子午岭天然油松林、人工油松林、人工落叶松林、人工刺槐林四种林分的土壤种子库特征初步研究结果表明 :人工油松林种子库储量平均为 675 .9粒 /m2 ,人工刺槐林为648.8粒 /m2 ,人工落叶松林为 839.4粒 /m2 ,天然油松林为 45 5粒 /m2 ,各林分土壤种子库储量属中等水平 ;本次调查的天然油松林种子库种子活力为零 ,人工油松林种子库活力种子占 0 .5 % ,人工落叶松林种子库活力种子占 4.2 % ,刺槐林种子库活力种子占 74.4%。除人工刺槐林种子库种子质量较高外 ,针叶林各林分种子库种子质量都较差 ;人工油松林林下油松幼苗的分布密度平均为 1～ 3株 /m2 ,人工刺槐林林下多见灌木幼苗 ,另两种林分林下幼苗较少 ,表明不同林分土壤种子库种子都具有一定的萌发能力 ;从各林分土壤种子库的组成看 ,主要树种的种子在种子库中所占比例都在 85 %以上 ,人工油松林土壤种子库物种多样性指数较高 ,而其它林分土壤种子库物种多样性指数均较小 ;土壤种子库中 80 %左右的种子集中分布在枯枝落叶层和 0 - 2 cm土壤层中 ,下层种子数量很少 ;方差分析表明 ,枯枝落叶层厚度、树高、郁闭度、胸径等因子变化对土壤种子库储量影响显著。综合分析认为 ,子午岭主要森林类型土壤种子库能够为林分的天然更新提供基本条件。 相似文献
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Use of phages for identifying the citrus canker bacterium Xanthomonas campestris pv. citri in Taiwan
Phages CP115 and CP122, which were isolated from canker lesions on grapefruit and Liucheng sweet orange, respectively, showed a high degree of specificity with respect to lysis of test bacterial strains. When used jointly, they lysed 135 (97·8%) out of 138 Xanthomonas campestris pv. citri strains isolated from the canker lesions on leaves, twigs, and fruits of various citrus species, cultivars, and hybrids grown throughout Taiwan, but they did not lyse other X. campestris pathovars and other phytopathogenic bacteria, nor other bacteria isolated from soil, clinical or environmental samples. Of 252 CP115/CP122-sensitive and 78 CP115/CP122-resistant bacterial strains with colony characteristics typical of or similar to those of X. campestris pv. citri , isolated from canker lesions of various citrus plants in diverse growing regions in Taiwan, 250 (99·2%) and 76 (97·4%) strains were pathogenic and non-pathogenic, respectively, when inoculated into Liucheng sweet orange or Mexican lime. Thus, phages CP115 and CP122, when used jointly, appear to be applicable for identifying X. campestris pv. citri in Taiwan. 相似文献
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Slugs are major pests of many crops, including winter wheat, in temperate climates, yet current methods of control are often unreliable. The aim of this study is to investigate the potential for common legume species to act as an alternative source of food, or trap crop, for the most damaging agricultural pest species, the grey field slug, Deroceras reticulatum Müller, thereby reducing damage to the wheat crop. A series of three controlled-environment experiments were designed to assess this aim. Individual slugs were fed leaves of one of ten legume species together with winter wheat leaves for a 72-h period. A clear hierarchy of acceptability was shown, with red clover, lucerne, lupin and white clover showing significantly higher Acceptability Indices than the other six species tested. Red clover produced the greatest reduction in mean wheat consumption (78%) from day 1 to day 3. When species were fed individually, red clover was consumed in significantly greater quantities than any of the other treatments: 40% more than white clover and 56% more than wheat. Furthermore, when fed with red clover the amount of wheat consumed was some 50% less than when the latter was fed alone. The results indicate that legumes vary greatly in their acceptability to D. reticulatum and it is essential that a legume with a high Acceptability Index is chosen, which results in the least amount of wheat consumed. 相似文献
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在样方调查的基础上,应用校正χ2检验,结合Jaccard关联指数、Pearson 相关系数和Spearman 秩相关系数,研究了银川平原湿地植物群落的种间关系, 计算测定了33 种常见植物共528个种对的种间关联关系。结果表明: ① 3种检验方法表达的种间关系相似但不完全相同。 χ2检验共有24个种对正关联, 4个种对负关联,其中有12对极显著正关联,1个种对极显著负关联; Pearson 相关系数检验,有30 个种对正相关,其中有19个种对极显著正相关,无负相关种对; Spearman 秩相关系数检验,有50个种对呈正相关,8个种对呈负相关,其中有31个种对极显著正相关,1个种对极显著负相关。② 银川平原湿地33种常见植物可划分为4个生态种组,即水生植物种组、湿生植物种组、中生植物种组和旱生植物种组,组内植物间多为显著正关联,种组植物间多为负关联。③ 银川平原湿地植物群落存在独立分布格局,植物群落不够稳定, 尚处于不断的演替之中。 相似文献
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为明确外来入侵植物对本地湿地植物多样性的影响，在北京市湿地选择23个样地共245个样方进行物种多样性调查，并从不同植物性状数据库获取样方中所有植物的株高、叶长、叶宽、叶面积和比叶面积等10个功能性状数据，对比分析入侵群落与本地群落的物种多样性、系统发育多样性和功能多样性特征。结果显示，在北京市湿地共记录到26种外来入侵草本植物，隶属10科19属，其中，菊科外来入侵植物种类最多，有10种。除比叶面积、叶片碳含量和株高的系统发育信号显著外，其余7种植物功能性状的系统发育信号均不显著，表明大多数功能性状未表现出系统发育保守性。入侵群落所有物种的物种多样性指标Shannon-Wiener多样性指数、物种丰富度指数和Simpson优势度指数以及系统发育多样性指标谱系多样性和平均最近谱系发育距离均显著高于本地群落和入侵群落本地物种，而入侵群落本地物种的功能分散指数和Rao''Q二次熵指数均显著高于本地群落，表明外来物种入侵改变了湿地植物的生物多样性，且外来物种入侵后群落谱系多样性趋于发散，说明与本地植物亲缘关系越远的入侵物种越容易在湿地群落中建立种群，符合达尔文归化假说。 相似文献
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松材线虫侵染对马尾松、黑松水分及其相关代谢的影响 总被引：7，自引：0，他引：7
以盆栽马尾松(Pinus massoniana)幼苗和离体水培黑松(P.thunbergii)、马尾松为材料,研究了松材线虫(Bursaphe-lenchus xylophilus)侵染对寄主水分、游离脯氨酸及叶绿素含量的影响以及由此引起的幼苗萎蔫与干旱萎蔫间的差异。松苗和离体枝接种松材线虫后,茎部相对含水量逐渐下降,早期下降缓慢,中后期加快。叶片变化滞后于茎部,相对含水量的明显下降发生在叶片褐变萎蔫症状出现之后(病害发展后期)。游离脯氨酸含量、叶绿素含量变化完全随叶片相对含水量的变化而变化。水分状况是影响受侵植株叶片脯氨酸和叶绿素含量的决定因子。自然干旱枯萎和由松材线虫侵染引起枯萎的松幼苗,两者从枯萎方式到茎、叶相对含水量的变化均存在显著差异。 相似文献