江苏垦区小麦赤霉病菌对多菌灵的抗性监测及其替代杀菌剂的防病效果

近年来的调查结果表明,江苏垦区小麦赤霉病菌群体中抗多菌灵菌株的频率逐年上升,多菌灵防效逐年下降,部分农场采用多菌灵防治几乎失效。为了筛选替代多菌灵的药剂,我们在白马湖等6个农场对几种新杀菌剂进行了田间药效试验。结果表明,25%氰烯菌酯SC、40%叶菌唑SC和25%丙硫菌唑WP在所有农场都有较好的防治效果,其中25%丙硫菌唑WP对小麦赤霉病的防治效果最好,在所有农场其防效都超过80%,防治后乳熟期和成熟期病穗率变化不大。40%叶菌唑SC、25%丙硫菌唑WP以及25%氰烯菌酯SC和43%戊唑醇SC混用有显著增产作用,并能大幅度降低籽粒中DON含量。作者认为赤霉病的防治应立足种植抗(耐)病品种,扬花期选用有效杀菌剂适期进行防治。氰烯菌酯、叶菌唑和丙硫菌唑可作为多菌灵的替代药剂。     

叶菌唑95%原药气相色谱分析方法研究

本文采用毛细管气相色谱法,以二十二烷为内标,HP-5毛细管柱和氢火焰离子化检测器,对叶菌唑原药进行分离和定量分析。结果表明,该分析方法的线性相关系数为0.999 4,标准偏差为0.32,变异系数为0.33%,平均回收率为100.45%。     

Effect of azole fungicide mixtures,alternations and dose on azole sensitivity in the wheat pathogen Zymoseptoria tritici

The evolution of fungicide resistance in the cereal pathogen Zymoseptoria tritici is a serious threat to the sustainability and profitability of wheat production in Europe. Application of azole fungicides has been shown to affect fitness of Z. tritici variants differentially, so it has been hypothesized that combinations of azoles could slow the evolution of resistance. This work assessed the effects of dose, mixtures and alternations of two azoles on selection for isolates with reduced sensitivity and on disease control. Naturally infected field trials were carried out at six sites across Ireland and the sensitivity of Z. tritici isolates monitored pre‐ and post‐treatment. Epoxiconazole and metconazole were applied as solo products, in alternation with each other, and as a pre‐formulated mixture. Full and half label doses were tested. Isolates were partially cross‐resistant to the two azoles, with a common azole resistance principal component accounting for 75% of the variation between isolates. Selection for isolates with reduced azole sensitivity was correlated with disease control. Decreased doses were related to decreases in sensitivity but the effect was barely significant (P = 0·1) and control was reduced. Single applications of an active ingredient (a.i.) caused smaller decreases in sensitivity than double applications. Shifts in sensitivity to the a.i. applied to a plot were greater than to the a.i. not applied, and the decrease in sensitivity was greater to the a.i. applied at the second timing. These results confirm the need to mix a.i.s with different modes of action.     

叶菌唑原药高效液相色谱分析方法研究

本文采用高效液相色谱法,以甲醇+水为流动相,使用CAPCELL PAK C18(5μm)不锈钢柱,二极管阵列检测器,在220nm波长下对叶菌唑原药进行分离和定量分析。结果表明,该分析方法的线性相关系数为0.999 8;标准偏差为0.24;变异系数为0.25%;平均回收率为99.84%。     

叶菌唑与4种杀菌剂复配对小麦赤霉病的毒力及防效

采用菌丝生长速率法测定了叶菌唑分别与咪鲜胺、戊唑醇、丙硫菌唑和氟啶胺的几种不同配比复配剂对禾谷镰孢菌的室内联合毒力,并通过田间试验评价复配剂对小麦赤霉病的防效。结果表明,叶菌唑、咪鲜胺、戊唑醇、丙硫菌唑和氟啶胺对禾谷镰孢菌的有效抑制中浓度(EC_(50))分别为0.016 3～0.038 3、0.014 7、0.280 7、0.094 5、0.230 0μg/mL,复配剂叶菌唑∶咪鲜胺1∶2和叶菌唑∶戊唑醇1∶1具有增效作用,SR值分别为1.540 5和1.515 3。按此比例制备了30%叶菌唑·咪鲜胺水乳剂和20%叶菌唑·戊唑醇悬浮剂用以进行田间防效试验,结果显示,这2个复配剂的田间防效均与用量呈正相关性,且一次防效均在65%以上,并且对小麦安全,这一结果表明叶菌唑与咪鲜胺、戊唑醇这2种不同作用机制的杀菌剂可以复配使用,大大延缓了小麦赤霉病菌抗药性的进一步加剧,为赤霉病的综合防控和抗药性治理提供依据,具有良好的市场开发前景。     

戊唑醇与羟菌唑对小麦赤霉病的防治效果及对小麦产量的影响

通过室内和田间药效试验,研究了新型三唑类杀菌剂戊唑醇与羟菌唑对小麦赤霉病的防治效果。温室盆栽试验结果表明:25%的戊唑醇(3.15mL/L)、6%的羟菌唑(3.75mL/L)可有效控制赤霉病菌在小麦穗部小穗之间的扩展,防效高于多菌灵常规用量。田间药效测定结果表明:与对照相比,接种前2d喷药与接种后2d喷药,2001年,戊唑醇可使小麦赤霉病病情指数分别减少80.32%和70.64%,产量增加12.95%与8.74%;羟菌唑可使小麦赤霉病病情指数减少80.5%和68.0%,产量增加11.41%和11.45%;2002年,在小麦赤霉病严重发生的情况下,戊唑醇能使小麦赤霉病病情指数减少76.47%和78.67%,羟菌唑能使小麦赤霉病病情指数减少82.06%和81.89%,产量增加极显著。说明这2种药剂可以作为防治小麦赤霉病的替代品种。     

Effect of adjuvants on the performance of the new cereal fungicide,metconazole. II Field trials

Glasshouse trials had shown that the activity of metconazole formulations against cereal foliar diseases could be enhanced by alcohol ethoxylate adjuvants. A series of soluble liquid (SL) formulations of metconazole had been prepared containing adjuvant: metconazole ratios of 5:1, 7.5:1, 10:1, 15:1 m/m (SL1, SL2, SL3, SL4) which glasshouse trials had shown could give equivalent performance to an emulsifiable concentrate formulation, (ECM) of metconazole at application rates up to three- or four-fold lower than that of ECM alone. A field trials programme was undertaken to compare the performances of these SL formulations with ECM at 120 g AI ha^?1, through a range of application rates (48, 60, 72, 84 g AI ha^?1), in a non-orthogonal factorial trial design against diseases that occurred naturally (Septoria tritici Rob., Puccinia recondita Rob., Pyrenophora teres Drechs., Erysiphe graminis DC) or by artificial inoculation (Leptosphaeria nodorum Muell.), on either Triticum aestivum L. or Hordeum vulgare L. The results from trials in three locations showed that the commercially acceptable performance of ECM at 120 g AI ha^?1, in giving high levels of control of P. recondita, S. tritici and L. nodorum (both prophylactic and therapeutic activity) on T. aestivum. and of E. graminis and P. teres on H. vulgare, could be matched or improved by SL2, SL3 and SL4 at 72 g AI ha^?1. Furthermore, control of E. graminis f. sp. tritici Marchal by these SL formulations at this application rate was better than that by ECM at 120 g AI ha^?1, though the levels of control still remained below commercial acceptability for therapeutic activity. Nevertheless, substantial reductions in the application rate of metconazole have been achieved by using one-pack adjuvant-containing formulations in field trials, while still maintaining excellent control of a range of cereal foliar diseases. The choice between these SL formulations could therefore be made on other grounds such as cost/performance and ease of formulation.     

叶菌唑在小麦中的残留消解及膳食风险评价

为评价叶菌唑在小麦中的残留行为及其产生的膳食摄入风险,于北京、安徽及黑龙江进行了1年3地田间试验,建立了叶菌唑在小麦中的残留分析方法,并对我国不同人群的膳食暴露风险进行了评价。样品用乙腈提取,经Florisil固相萃取柱净化,气相色谱-氮磷检测器(GC-NPD)检测,外标法定量。结果表明:在0.02~10 mg/kg的添加水平下,叶菌唑在小麦籽粒和植株中的平均回收率在81%~101%之间,相对标准偏差(RSD)在2.1%~9.1%之间;其在小麦籽粒和植株中的定量限(LOQ)分别为0.02和0.04 mg/kg。叶菌唑在小麦植株中的消解符合一级动力学方程,半衰期为4.9~7.3 d。收获时小麦籽粒中叶菌唑的最大残留量为0.037 mg/kg,低于美国和欧盟设定的最大残留限量(MRL)0.15 mg/kg。针对我国不同人群的膳食摄入及风险评估暴露,风险商值(RQ)在0.001~0.002之间,表明叶菌唑在小麦中的膳食摄入风险较低。