霜脲氰与不同杀菌剂混配对两种霜霉病菌的增效作用

采用叶盘法（定量喷药）测定霜脲氰与不同杀菌剂混配对黄瓜和葡萄霜霉病菌抗甲霜灵菌株的增效作用,证实了霜脲氰加代森锰锌或二者再加恶霜灵以不同比率混配对黄瓜、葡萄霜霉病菌均明显增效,发现了霜脲氰与碱式硫酸铜1：8混配对黄瓜霜霉病菌增交,代森锰锌（1：8）或再加恶霜灵（1：8：1）对葡萄霜霉病菌的增效作用随着供试菌株对甲霜灵抗性水平的提高而增强。霜脲氰与代森锰锌1：7混配以保护、治疗、铲除方式处理黄瓜叶盘,对黄瓜霜霉病菌均表现增效。     

拮抗细菌P78对黄瓜疫病及丝瓜霜霉病的防治作用

本试验从马来西亚和我国台湾、广州等地区采集土样２２８个,用常规平板稀释法分离,获得细菌菌株４２６个,在温室黄瓜苗期直接人工接种疫病菌进行测定,筛选出对黄瓜疫病有拮抗作用的细菌菌株Ｐ７８。其摇瓶发酵液在温室内人工接种条件下,防治黄瓜疫病效果平均达９５．２％;在田间小区中,Ｐ７８有效物质可防治丝瓜霜霉病,初提物稀释２０倍的防治效果可达到６４％。该菌株是分泌活性物质起作用的,其活性物质可耐高温和酸碱处理。     

PCR detection of Pseudoperonospora humuli in air samples from hop yards

Downy mildew of hop, caused by Pseudoperonospora humuli , is an important disease in most regions of hop production and is managed largely with regular fungicide applications. A PCR assay specific to P . humuli and the related organism P .  cubensis was developed and used to monitor airborne inoculum in hop yards to initiate fungicide applications. The PCR amplified as little as 1 fg of genomic DNA of P . humuli , and yielded an amplicon in 70% of reactions when DNA was extracted from single sporangia. In the presence of 25 mg of soil, an amplicon was amplified in 90% of reactions when DNA was extracted from 10 or more sporangia. During nine location-years of validation, PCR detection of the pathogen in air samples occurred no later than 8 days after the appearance of trace levels of disease signs and/or detection of airborne spores in a volumetric spore sampler. Inoculum was detected on average 4·5 days before (range −8 to 14 days) the first appearance of basal spikes in six commercial yards, or 1·3 days after (range −5 to 1 days) sporangia were detected in a volumetric spore sampler in experimental plots. In commercial yards, use of PCR to initiate the first fungicide application led to enhanced disease control or a reduction in fungicide use in four of six yards compared to growers' standard practices. These results indicate that the efficiency and efficacy of hop downy mildew management can be improved when control measures are timed according to first detection of inoculum.     

64%噁霜灵锰锌(福乐尔)防治黄瓜霜霉病药效实验

进行了国产恶霜灵锰锌与进口杀毒矾在防治黄瓜霜霉病的药效对照试验。结果表明,两者400倍液的防治效果分析为89.9%和88.6%,两者500倍液、600倍液的防治效果为84%、86.3%、72%、73.2%,结果证实两者对黄瓜霜霉病的防治效果均很好。根据数理统计结果,认为二者在防治效果上无显著差异,但国产恶霜灵锰锌价格低廉,值得推广。     

Biological Mode of Action of Dimethomorph onPseudoperonospora cubensis and Its Systemic Activity in Cucumber

Dimethomorph is a fungicide with high activity against Peronosporomycetes plant pathogens. The present study showed that dimethomorph is effective on controlling the oomycete fungal pathogen Pseudoperonospora cubensis causing downy mildew on cucumber. The fungicide did not affect zoospores discharge from sporangia of P. cubensis, but it strongly inhibited mycelial growth and sporangial production in vitro and increased lysis of zoospores. Dose of 2 mg L^-1 of dimethomorph was sufficient to inhibit mycelial growth and sporangial production of P. cubensis on leaf disks, 5 mg L^-1 was enough to lyse zoospores of P. cubensis, and 25 mg L^-1 was required to inhibit sporangial production on detached leaves. In whole plant tests, dimethomorph exhibited strong protective and curative activity. Dimethomorph when applied at a dose of 300 mg L^-1 for 1, 3, 5, 7 days before inoculation exhibited 100% efficacy on disease control. On the other hand, efficacies of 67.1 and 31.5% were obtained when the same dose of dimethomorph was applied for 1 and 3 days after inoculation, respectively. So dimethomorph had persistence effect on leaves for 7 days at least and exhibited strong protective and curative activity. Bioassay analyses showed that dimethomorph could be translocated in the xylem system, redistributed in the leaf, and penetrated from the upper surface to the lower surface of the leaf but could not be translocated in phloem system or transferred from the roots to leaves of cucumber plants in sufficient amounts for disease control. The biocharacteristics of dimethomorph make it well suitable for integration of a control programme against downy mildew disease on cucumber and as a component to delay other peronosporomycetes fungicide-resistance development.     

黄瓜霜霉病菌抗药性的发生及化学防治

由古巴假霜霉引起的黄瓜霜霉病是黄瓜上的毁灭性病害,主要依靠化学防治,但采取将化学防治与预测预报、棚室通风、利用抗病品种、生物防治相结合的综合防治策略和预防性施药措施,可有效减轻黄瓜霜霉病的为害。主要防治药剂有接触性杀菌剂和内吸性杀菌剂,必须交替或混用以延缓抗药性的产生。黄瓜霜霉病菌对苯基酰胺类杀菌剂的抗性普遍发生,在日本检测到对QoI类杀菌剂的田间抗性菌株,必须评估对新型杀菌剂的抗性风险,制订相应的抗药性治理对策,以延长药剂的使用寿命。     

棱角丝瓜不同品种对霜霉病抗性的相关研究

用不同抗性的丝瓜品种为材料,通过对气孔、糖含量、过氧化物酶、多酚氧经酶等多项指标的测定,结果表明：线瓜叶片中多酚氧化酶活性、还原性糖／可溶性糖比值、叶处表皮气孔密度与丝瓜对霜霉病的抗性呈负相关,其相关系数分别为－０．９８６１、－０．７１６５、－０．９６９２;而可溶性总糖含量与抗病性呈正相关（ｒ＝０．９１１５）;与还原性糖含量及过氧化物酶活性无关,气孔大小与抗病性无关。     

芽孢杆菌对黄瓜霜霉病的防治效果研究

经黄瓜霜霉病孢子囊萌发抑制试验明确,芽孢杆菌菌株Z-X-3、Z-X-10对黄瓜霜霉病菌有较强拮抗作用。离体叶片法和温室防病试验表明,两菌株对黄瓜霜霉病有较好的防治效果,相对保护效果分别达46.42％、41.55％;治疗效果分别达46.30％、44.44％,高于农药克霜氰的31.81％、37.03％。     

黄瓜霜霉菌ITS区序列分析反应体系的构建及优化

文章以黄瓜霜霉菌为材料,采用改良的CTAB方法提取基因组DNA,研究了黄瓜霜霉菌ITS区序列分析中PCR反应体系的各主要成分对检测结果的影响,确立了适宜的退火温度和反应体系。优化后的反应体系(25μL)为:采用引物ITS1/ITS4各40 ng,60 ng DNA模板,2.5 mmol·L-1 Mg2+2.0μL,2.5 mmol·L-1 dNTP 1.5μL,Taq酶1 U。优化的PCR扩增程序为:94℃预变性3 min,94℃50 s,52.2℃40 s,72℃1.5 min。在这一条件下运行35个循环;72℃延伸7 min。采用此反应体系和扩增程序,对采自黑龙江省不同地区的31份黄瓜霜霉菌基因组DNA进行PCR扩增,均可得到一条约为900 bp的条带。     

脱落酸诱导黄瓜对霜霉病的抗性研究

以"新泰密刺"黄瓜为试材,选用5、10、20、30、40mg/L的脱落酸(ABA)处理黄瓜幼苗,研究外源ABA对黄瓜抗霜霉病的影响。结果表明:适当浓度ABA处理可诱导黄瓜抗霜霉病,降低病情指数,诱导叶片防御酶POD、SOD、PAL、PPO活性升高。其中10mg/L浓度处理表现效果最好;诱导抗性可持续8d以上,第4天防御酶活性均高于第8天。