Control of lettuce big-vein disease by application of fungicides and crop covers

One of the economically important diseases of lettuce is lettuce big-vein disease (LBVD), which leads to severe yield losses. LBVD is associated with a complex of two viruses, Lettuce big-vein associated virus (LBVaV) and Mirafiori lettuce big-vein virus (MLBVV). These viruses are transmitted by motile zoospores of Olpidium spp. fungi, which persist in the soil for decades through resting spores. In greenhouse and field experiments, this study tested whether changing plant and soil temperatures together with fungicide application would have a significant effect on controlling LBVD in lettuce. Soil fumigation with metam sodium was not effective at controlling the disease, as opposed to treatment with chloropicrin and methyl bromide. Moreover, the fungicides carbendazim and fluazinam were effective in reducing the incidence of Olpidium virulentus. Nevertheless, control of the fungal vector did not seem to be sufficient to control the disease due to the transition ability of the virus under low vector abundance. Crop covers, which affect the favourable environmental conditions for the viruses by lowering soil temperature and raising air temperature, reduced the disease symptoms. Combining fungicides with crop cover had a synergistic effect on reducing disease symptoms, thus providing a sustainable solution for LBVD.     

基于叶绿素评价氟啶胺对几种农作物的生态安全性

对大田栽培作物玉米、棉花、红薯和花生,用喷雾器喷施不同浓度杀菌剂氟啶胺,24 h后测定四种作物叶绿素和类胡萝卜素的含量。结果表明：2 000至3 000倍氟啶胺对花生、3 000倍氟啶胺对红薯和棉花是安全的,而氟啶胺对玉米则几乎是不利的。     

不同杀菌剂对黄瓜靶斑病菌的毒力作用特性比较

为筛选防治黄瓜靶斑病的有效药剂，采用菌丝生长速率法、孢子萌发法和芽管伸长法测定了19种杀菌剂对黄瓜靶斑病菌的毒力，探究了4种毒力较高杀菌剂对病原菌菌丝形态的影响。结果表明:氟啶胺、吡唑萘菌胺、咯菌腈和四霉素对黄瓜靶斑病菌菌丝生长、孢子萌发和芽管伸长各生长发育阶段均有较强的抑制活性，其中，4种药剂抑制菌丝生长的平均EC₅₀值分别为0.516 3、1.538、1.605和0.648 2 mg/L，抑制孢子萌发的平均EC₅₀值分别为0.164 4、1.359、1.127和0.002 5 mg/L，抑制芽管伸长的平均EC₅₀值分别为0.189 6、0.144 7、0.060 4和0.001 5 mg/L；啶酰菌胺、百菌清和肟菌酯3种不同作用机制杀菌剂对黄瓜靶斑病菌孢子萌发和芽管伸长的抑制活性较强，3种药剂抑制孢子萌发的平均EC₅₀值分别为1.564、0.373 0和0.021 3 mg/L，抑制芽管伸长的平均EC₅₀值分别为0.629 5、0.233 4和0.405 0 mg/L，但对菌丝生长的抑制作用较弱，平均EC₅₀大于16 mg/L；氟啶胺、吡唑萘菌胺、咯菌腈和四霉素可引起黄瓜靶斑病菌菌丝不同程度的异常生长，主要表现为菌丝隔膜间距变小、菌丝节间肿大、主菌丝上二次分枝发生频繁、菌丝变形黏连、菌丝新分枝处生长受抑制或分生孢子生长变形。研究表明，氟啶胺、吡唑萘菌胺、咯菌腈和四霉素对黄瓜靶斑病菌具有较高的毒力，在黄瓜靶斑病的田间防治中具有较好的开发应用潜力。     

福建省玉米小斑病菌对氟啶胺的敏感性及其与不同杀菌剂间的交互抗性

为明确福建省玉米小斑病菌Cochliobolus heterostrophus对氟啶胺的敏感性及其与不同杀菌剂间的交互抗性，采用菌丝生长速率法测定了该省5个地区的73株玉米小斑病菌菌株对氟啶胺的敏感性。结果表明，供试73株玉米小斑病菌菌株对氟啶胺具有较高的敏感性，所有菌株的有效抑制中浓度EC₅₀在0.0023~1.2863 μg/mL之间，平均值为0.2573 μg/mL，其敏感性频率呈连续单峰曲线分布，符合正态分布，因此可将EC₅₀平均值0.2573 μg/mL作为福建省玉米小斑病菌对氟啶胺的敏感基线；5个地区的菌株群体对氟啶胺的敏感性差异不显著，但是不同地区的菌株个体间差异较大；氟啶胺与多菌灵、百菌清、丙环唑、烯唑醇、咪鲜胺和异菌脲之间均不存在交互抗性。     

氟啶胺对白菜根肿病的防治效果

白菜根肿病是威胁大白菜生产的一种土传性病害。为了筛选对白菜根肿病有效的杀菌剂,在室内和田间利用灌根方法测定氟啶胺对白菜根肿病的防治效果。室内药效测定结果显示氟啶胺乳油(有效质量浓度2.5和5μL·mL-1)的防治效果分别为89.9%和89.5%,均高于甲基硫菌灵的防治效果88%。氟啶胺乳油(有效质量浓度5和2.5μL·mL-1)的田间防治效果分别为77.6%和69.4%,均高于甲基硫菌灵的防治效果37.4%。结果表明,氟啶胺乳油可以用来防治白菜根肿病。     

气相色谱电子捕获法测定氟啶胺在辣椒和土壤中动态残留

 【目的】建立辣椒和土壤中氟啶胺残留的分析方法，探明氟啶胺在辣椒田中使用后的残留行为，为安全施药提供依据。【方法】采用田间试验法研究氟啶胺在辣椒和土壤中的残留消解动态。【结果】氟啶胺在辣椒中半衰期为2.5～3.7 d，土壤中为1.2～4.2 d。使用氟啶胺50%悬浮剂，制剂用量为495 g•ha-1。（有效成分247.5 g•ha-1），施药4次， 距末次施药后7 d收获的辣椒中氟啶胺残留量小于0.06 mg•kg-1，低于韩国规定的最大残留限量值（0.3 mg•kg-1）。【结论】该分析方法操作简单，精密度、准确度和灵敏度都符合农药残留标准要求，适用于辣椒和土壤中的氟啶胺残留测定；建议氟啶胺50%悬浮剂在辣椒上防治病害，最多使用4次，用量为247.5～495 g•ha-1（有效成分123.75～247.5 g•ha-1），安全间隔期为7 d。     

Molecular characterization and biological response to respiration inhibitors of Pyricularia isolates from ctenanthe and rice plants

The molecular profile and the biological response of isolates of Pyricularia oryzae Cavara obtained from ctenanthe to two strobilurins (azoxystrobin, kresoxim-methyl) and the phenylpyridinamine fungicide fluazinam were characterized, and compared with isolates from rice plants. Five different isozymes (alpha-esterase, lactate, malate, isocitrate and sorbitol dehydrogenases) and five random decamer primers for RAPD-PCR were used to generate molecular markers. Using unweighted pair-group with arithmetic average analysis, ctenanthe isolates were found to form a separate group distinct from that of the rice isolates for both sets of markers. Amplified polymorphic sequences of mitochondrial cytochrome b that were digested with Fnu4HI or StyI revealed no differences among Pyricularia isolates at amino acid positions 143 or 129 which confer resistance to strobilurins in several fungi. In absence of the alternative respiration inhibitor salicylhydroxamic acid (SHAM) the three fungicides showed inferior and variable efficacy, with a trend toward the rice isolate being less sensitive. The addition of SHAM enhanced the effectiveness of all fungicides against isolates regardless of their origin. Appressorium formation was the most vulnerable target of action of the respiration inhibitors and azoxystrobin the most effective. This is the first report of a comparison between the molecular profiles and sensitivities to respiration inhibitors for Pyricularia oryzae isolates from a non-gramineous host and from rice.     

Comparison of the NegFry decision suport system with routine fungicide application for the control of potato late blight in Ireland

Summary Field experiments between 1996 and 2000 compared the efficacy of fungicide programmes applied in accordance with the NegFry and Met éireann (Mé) decision support systems (DSS) for the control of late blight with 7- and 10-day routine fungicide programmes. The Mé DSS reduced fungicide use by 68% and 54% respectively while NegFry reduced fungicide use by 49% and 27% compared with the 7- and 10-day programmes. The NegFry DSS was similar to the 10-day routine programme in terms of late blight control, quality and marketable yield. A similar result was found when the NegFry DSS was compared with a 7-day routine mancozeb programme (included for two seasons only). Within the NegFry DSS the use of fluazinam resulted in improved yield, foliage blight and tuber blight control compared with mancozeb, but this benefit was significant for tuber blight only. The Mé DSS resulted in inferior disease control, yield and quality.     

超高效液相色谱串联质谱法测定马铃薯和土壤中氟啶胺残留

建立超高效液相色谱-电喷雾串联四极杆质谱快速测定马铃薯和土壤中氟啶胺残留的分析方法。样品经固相萃取净化,以液相色谱-质谱联用仪测定和确证,外标法定量。结果表明。该方法对氟啶胺的最低检出限为8μg／kg。在8．150-521．6μg／L线性范围内,相关系数为0．9999,回收率在81．96～116．66％之间,相对标准偏差〈10％（n=5）。     

氟啶胺防治柑橘黑点病效果评价

氟啶胺是我国登记用于防治柑橘黑点病的药剂,但其对柑橘黑点病的防治效果还未见报道,评价氟啶胺的药效对生产上指导柑橘黑点病的防治有重要意义。本研究测定了氟啶胺对柑橘黑点病菌孢子萌发和菌丝生长的抑制效果及田间防效。结果显示氟啶胺对菌丝生长和孢子萌发的抑制效果均好于代森锰锌,但在大田试验中氟啶胺防治效果不稳定,受环境影响较大,添加矿物油能在一定程度上提高其防效。该结果表明氟啶胺对柑橘黑点病具有良好的防治潜力,可对其进行更细致的研究。