Ts-86提取液防治黄瓜白粉病的初步研究

测试了中草药Ts-86提取液对黄瓜白粉病的防治作用,并对其稳定性、持效期及抑菌谱等作了进一步研究。结果表明,Ts-86提取液的200倍液防效达93.35％,优于15％粉锈宁可湿性粉剂1 000倍液的防效;其酸碱稳定性与热稳定性较差,只在中性或微酸微碱条件下活性较高,且经100℃处理的活性最高;经100℃处理后,其500倍液防治作用的持效期可达6 d:抑菌谱相对广泛。     

设施草莓白粉病发生规律及综合防治技术

白粉病是设施草莓主要病害之一,特别是当前生产上主栽品种红颜、丰香、章姬等发病较重,严重影响草莓品质及产量。介绍了草莓白粉病的发病特点、发病高峰期及危害症状,并从农业防治、化学防治、熏蒸防治等方面总结了草莓白粉病的防治方法,以期为更好地防治草莓白粉病提供参考。     

Effects of foliar- and root-applied silicon on the enhancement of induced resistance to powdery mildew in Cucumis sativus

Two cucumber ( Cucumis sativus ) cultivars differing in their resistance to powdery mildew, Ningfeng No. 3 (susceptible) and Jinchun No. 4 (resistant), were used to study the effects of foliar- and root-applied silicon on resistance to infection by Podosphaera xanthii (syn. Sphaerotheca fuliginea ) and the production of pathogenesis-related proteins (PRs). The results indicated that inoculation with P. xanthii significantly suppressed subsequent infection by powdery mildew compared with noninoculation, regardless of Si application. Root-applied Si significantly suppressed powdery mildew, the disease index being lower in Si-supplied than in Si-deprived plants, regardless of inoculation treatment. The resistant cultivar had a more constant lower disease index than the susceptible cultivar, irrespective of inoculation or Si treatment. Moreover, with root-applied Si, activities of PRs (for example peroxidase, polyphenoloxidase and chitinase) were significantly enhanced in inoculated lower leaves or noninoculated upper leaves in inoculated plants of both cultivars. Root-applied Si significantly decreased the activity of phenylalanine ammonia-lyase in inoculated leaves, but increased it in noninoculated upper leaves. However, Si treatment failed to change significantly the activity of PRs in plants without fungal attack. Compared to the control (no Si), foliar-applied Si had no effects either on the suppression of subsequent infection by P. xanthii or on the activity of PRs, irrespective of inoculation. Based on the findings in this study and previous reports, it was concluded that foliar-applied Si can effectively control infections by P. xanthii only via the physical barrier of Si deposited on leaf surfaces, and/or osmotic effect of the silicate applied, but cannot enhance systemic acquired resistance induced by inoculation, while continuously root-applied Si can enhance defence resistance in response to infection by P. xanthii in cucumber.     

Phytogeny and Cross-infectivity of Powdery Mildew Isolates (Podosphaera fuliginea s. lat.) on Cosmos and Cucumber

To clarify the relationship between the phylogeny and infectivity of isolates of Podosphaera fuliginea s. lat. (= Sphaerotheca fuliginea s. lat.) from cosmos and cucumber, more than 50 powdery mildew isolates from these two plants were subjected to nucleotide sequencing or PCR-RFLP analysis of the rDNA internal transcribed spacer (ITS) region and cross-inoculation tests. The isolates from both cosmos and cucumber are genetically monotypic, and there are six nucleotide substitutions in the rDNA ITS region between isolates from cosmos and cucumber. Cross-inoculation tests of these isolates revealed that isolates from cosmos are not pathogenic on cucumber. Although isolates from cucumber produced conidia on leaves of cosmos in the laboratory, the conidial density was much lower than that from isolates from cosmos. This result, as well as the fact that the cucumber strain was not isolated from cosmos in fields, suggests that isolates from cucumber do not infect cosmos in the field. Therefore, powdery mildews on cosmos and cucumber can be regarded to have become specialized for their hosts both genetically and pathogenically. The present study reconfirms the close relationship between phylogeny and infectivity of powdery mildew fungi. Host specialization may be a trigger that causes genetic divergence of powdery mildew fungi. Received 28 June 2000/ Accepted in revised form 4 September 2000     

Biological control of cucumber powdery mildew with Tilletiopsis minor under greenhouse conditions

In growth cabinet and greenhouse experiments the efficacy ofTilletiopsis minor in controlling cucumber powdery mildew decreased as humidity was lowered. This effect could be counteracted by formulation of the mycoparasite with lipophilic substances, like Hora Oleo 11E and lipids from milk. These formulations, without the mycoparasite, were also found to be deleterious to powdery mildew development. In the long run, however, formulations withT. minor gave better biological control of cucumber powdery mildew than formulations alone.     

三羟鹅膏毒肽的反相高效液相色谱分离纯化

用反相高效液相色谱法,以0.02mol醋酸铵-乙腈为流动相和梯度洗脱模式,从灰花纹鹅膏菌中分离纯化出三羟鹅膏毒肽(amanin),产品纯度达96%以上,三羟鹅膏毒肽的分子量为903.3.     

灰花纹鹅膏菌及其生态习性

灰花纹鹅膏菌Amanita fuliginea Hongo的分类地位和生态习性国内一直没有详细报道.用形态解剖、HPLC和种群生态学研究方法对其研究表明日本学者Hongo对该菌的分类是正确的；它的毒素含量与欧洲的主要种毒鹅膏菌Amanita phalloides(Fr.∶Fr.)Link毒素含量相当，甚至更高.湘东湘南丘陵针栎混交林非常适宜该菌生长发育与演化.     

Screening of melon (Cucumis melo L.) germplasm for multiple disease resistance

Summary Melon germplasm was screened for cucumber green mottle mosaic virus (CGMMV), powdery mildew (Sphaerotheca fuliginea), downy mildew (Pseudoperonospora cubensis) and Fusarium wilt (Fusarium oxysporum f. sp. melonis) resistance under artificial conditions except downy mildew for which screening was done under natural epiphytotic conditions. High level resistance to all the four diseases was not recorded in any of the collections tested. Nevertheless, ertheless, resistance to three diseases was located in three germplasm. Wild Cucumis species C. figarei exhibited absolute resistance to CGMMV and Fusarium wilt and high level resistance to downy mildew. Phoot or snapmelon (Cucumis melo var. momordica) — a non-dessert from of Indian origin—was highly resistant to downy mildew and resistant to CGMMV and medium resistant to Fusarium wilt. Iroquois was resistant to powdery mildew and medium resistant to downy mildew and CGMMV.     

Relation in the inheritance of resistance to Pseudoperonospora cubensis rost and Sphaerotheca fuliginea poll. in cucumber (Cucumis sativusl. L.)

Summary Among the genes for resistance against Sphaerotheca fuliginea, the gene s for resistance of the hypocotyl is linked to or identical with gene p for resistance to Pseudoperonospora cubensis. This gene s is present in the cultivars Ashley, Poinsett, Natsufushinari, Pixie, Taipei and in accessions PI 179676. PI 212233 and PI 234517.Although gene s initially brings about some resistance of the true leaf, it appears that when s is present. other genes are necessary for complete resistance to S. fuliginea.     

Resistance to the gall mite and American gooseberry mildew in black currants in relation to season of leafing out

Summary In black currant (Ribes nigrum) backcross progenies segregating for resistance to the gall mite, Cecidophyopsis ribis Westw. (gene Ce from Ribes grossularia L.), and to American gooseberry mildew, Sphaerotheca mors-uvae (Schw.) Berk. (gene Sph ₃from R. glutinosum), significant differences in season of leafing out occurred between the resistant and susceptible classes. The data are consistent with the hypothesis that two additive genes, Lf ₁and Lf ₂, controlled season of leafing out and that Ce and Sph ₃ were linked with Lf ₁.