防治牡丹根腐病的有效药剂筛选

采用菌丝生长速率法和孢子萌发法,分别测定了咪鲜胺、醚菌酯、苯醚甲环唑、百菌清、多菌灵、代森锰锌等6种杀菌剂对牡丹根腐病菌的室内毒力。结果表明,6种药剂对病菌菌丝生长的EC50大小顺序为：咪鲜胺<多菌灵<代森锰锌<苯醚甲环唑<百菌清<醚菌酯,其中以咪鲜胺对牡丹根腐病病菌的菌丝生长抑制作用最强, EC50为0.200 mg/L;多菌灵、代森锰锌、苯醚甲环唑、百菌清依次减弱,醚菌酯的抑制菌丝生长的作用最小,EC50为33.98 mg/L。6种药剂对病菌孢子萌发的EC50大小顺序为：百菌清<咪鲜胺<苯醚甲环唑<多菌灵<代森锰锌<醚菌酯;其中以百菌清对牡丹根腐病菌的孢子萌发抑制作用最强,EC50为0.343 mg/L;咪鲜胺、苯醚甲环唑、多菌灵、代森锰锌依次减弱,醚菌酯抑制孢子萌发的作用最小,EC50为38.4 mg/L。     

25%咪鲜胺水乳剂对香蕉冠腐病的控制效果

采用生长速率法进行了25%咪鲜胺水乳剂对香蕉冠腐病的室内毒力测定,结果显示:该药剂对香蕉冠腐病菌的生长具有较强的抑制作用,EC90=31.7199mg/L,EC50=1.3651mg/L。采后防治试验表明:蕉果采后用25%咪鲜胺水乳剂有效浓度为500mg/kg浸渍处理,贮藏后18d对香蕉冠腐病的防效达到89.4%。     

8种杀菌剂对黄瓜枯萎病菌的室内毒力测定

采用菌落直径法,分别测定了7大类8种常用杀菌剂对黄瓜枯萎病菌的室内毒力。结果表明,8种供试杀菌剂对黄瓜枯萎病菌的作用效果均较好,其中三唑类丙环唑的毒力最高,EC50值为0.023mg/L。咪鲜胺、苯醚甲环唑、咯菌腈、百菌清和嘧菌酯的毒力也较高,EC50均低于1.0mg/L;多菌灵和异菌脲对黄瓜枯萎病的毒力分别为1.105和1.181mg/L,仍有较好的作用效果。     

9种杀菌剂对西瓜炭疽病菌的室内毒力测定及配比试验

为筛选防治西瓜炭疽病的高效低毒杀菌剂, 缓解和治理生产中病菌对药剂的抗性, 在室内离体条件下采用生长速率抑制法及孢子萌发抑制法测定了9种杀菌剂对西瓜炭疽病菌( Colletotrichum orbiculare )的毒力。结果表明, 嘧菌酯、咪鲜胺和甲基硫菌灵对病原菌菌丝生长的EC50在0.093 3~0.118 2 mg/L之间, 均小于1 mg/L, 表明西瓜炭疽病菌对上述杀菌剂比较敏感; 百菌清、烯肟菌酯和戊菌唑的EC50在2.310 1~5.925 9 mg/L, 病菌对药剂的敏感程度相对较低; 代森锰锌、恶霉灵和多菌灵的EC50分别为36.876 3、74.466 6和99.898 5 mg/L, 抑菌活性较差。孢子萌发试验中, 嘧菌酯、咪鲜胺和甲基硫菌灵对病菌孢子萌发的抑制活性最高, EC50在0.069 4~0.167 2 mg/L之间; 百菌清、烯肟菌酯、代森锰锌的抑制活性次之, EC50在1.853 0~9.503 9 mg/L之间; 多菌灵的抑制活性相对最低, EC50为99.335 3 mg/L。将两种不同作用机理的杀菌剂嘧菌酯与咪鲜胺按照2∶1的比例混配, 联合毒力测定和评价结果表明两者混配对抑制西瓜炭疽病菌具有增效作用。     

稻田土壤8种真菌对4种杀菌剂的敏感性分析

基于ITS-5.8s rDNA区序列,初步鉴定了浙江大学试验基地稻田土壤的8种常见真菌。采用菌丝生长速率法测定了井冈霉素、多菌灵、咪鲜胺和三唑酮4种常用杀菌剂对这8种土壤真菌的抑菌活性,以及多菌灵与咪鲜胺混用对禾柄锈菌、黑曲霉和长枝木霉3种真菌菌丝生长的抑制作用。结果表明:8种真菌对咪鲜胺最敏感,EC50值在0.091~3.1 mg/L之间;多菌灵的EC50值在0.15~1.8 mg/L之间;三唑酮的EC50值在0.57~8.5 mg/L之间;井冈霉素的敏感性最低,EC50在12~94 mg/L之间。由4种杀菌剂的SSDs曲线分析结果得出,不同真菌对杀菌剂敏感性存在显著差异。当多菌灵与咪鲜胺按其EC50值分别以体积比3∶2、1∶1和7∶3混用时,增效系数分别为1.615、1.039和1.042,表现出一定的协同或相加作用。本研究结果为进一步阐明杀菌剂对稻田生态系统真菌群落的生态效应及杀菌剂的科学合理使用提供了重要依据。     

几种药剂对草莓炭疽病的效果

采用菌丝生长速率法测定了48%波尔多液可湿性粉剂、50%咪鲜胺可湿性粉剂、40%福美锌可湿性粉剂和70%代森联干悬浮剂4种药剂对草莓炭疽病菌的室内毒力。结果表明,4种药剂对菌丝生长的EC50的大小顺序为:50%咪鲜胺40%福美锌70%代森联48%波尔多液,50%咪鲜胺的EC50为6.24 mg/L。并选取毒力较好的50%咪鲜胺可湿性粉剂和40%福美锌可湿性粉剂进行了田间药效测定,48%波尔多液可湿性粉剂作为对照。试验发现:50%咪鲜胺可湿性粉剂在田间的效果最好,其800 mg/L处理在田间2次药后7 d的防效达到了80.26%,与对照药剂48%波尔多液可湿性粉剂间存在显著性差异。     

两种农药混配对水稻稻瘟病菌的室内毒力测定

采用抑制菌丝生长速率法,测定了多菌灵与咪鲜胺混配后对稻瘟病防治的增效作用以及两种杀菌剂的混配比例。试验结果表明,多菌灵与咪鲜胺的比例为5：5混配时,药剂表现出一定的增效作用,毒效比率为1．19,此时的共毒系数最高,为124．92。     

辣椒炭疽病病原鉴定及其杀菌剂毒力测定

从贵阳市花溪区磊庄村辣椒基地采集疑似炭疽病的典型的自然发病辣椒果实,采用组织分离、培养、形态学观察、致病性测定以及多基因分子系统学,确定病原菌的种类;采用菌丝生长速率法研究了8种杀菌剂对该病菌菌丝生长的抑制作用。结果表明,引起贵阳市花溪区磊庄村辣椒炭疽病的病原菌为尖孢炭疽菌Capsicum acutatum。室内毒力测定发现8种杀菌剂对尖孢炭疽菌均有一定的抑制作用,其中25%咪鲜胺EC和30%吡唑醚菌酯SC抑制效果最好,EC_(50)分别为0.253 5 mg/L和0.720 3 mg/L;其次为22.5%啶氧菌酯SC和22.7%二氰蒽醌SC,EC_(50)分别为7.249 5 mg/L和21.664 5 mg/L。将30%吡唑醚菌酯SC和22.7%二氰蒽醌SC按照9∶1、6∶4、3∶7、4∶6的比例混配,联合毒力测定和评价结果显示两者混配对该病菌具有协同增效作用,且25%咪鲜胺EC和22.5%啶氧菌酯SC以6∶4、4∶6、8∶2的比例进行混配时也表现出明显的增效作用。引起贵阳市花溪区磊庄村辣椒基地辣椒炭疽病的致病菌为尖孢炭疽菌。咪鲜胺、吡唑醚菌酯、啶氧菌酯和二氰蒽醌对该菌具有较好的抑制作用,可为辣椒炭疽病的田间防治提供参考依据。     

不同药剂对柑橘炭疽菌的毒力测定及田间防病效果

采用菌丝生长速率法测定了13种杀菌剂单剂及咪鲜胺与苯醚甲环唑复配组合对柑橘炭疽菌的室内毒力,并比较了不同复配组合的协同作用。结果表明,供试药剂对柑橘炭疽菌均具较好的抑制作用,多数杀菌剂EC50均低于1 mg/L,炭疽菌对咪鲜胺和苯醚甲环唑的敏感性较强,EC50分别为0.079 0、0.150 9 mg/L。将咪鲜胺和苯醚甲环唑进行复配,质量比为6∶4时抑菌活性最高,EC50为0.056 7 mg/L,增效系数为1.72。田间试验表明,25%咪鲜胺微乳剂和25%苯醚甲环唑微乳剂质量比6∶4复配剂1 000倍液、2 000倍液、3 000倍液均表现出较好的防治效果,施药3次后的防效分别为94.01%、91.45%、87.50%,明显高于其他药剂。     

江苏省水稻恶苗病菌对咪鲜胺和氰烯菌酯的敏感性

对采自江苏省姜堰、靖江和常州3个地区的水稻恶苗病样品进行了病原菌的分离和鉴定,利用菌丝生长速率法测定了病原菌对咪鲜胺和氰烯菌酯的敏感性。结果表明:分离得到77株水稻恶苗病菌Fusarium fujikuroi;咪鲜胺对水稻恶苗病菌的EC50值在0.020~1.333μg/m L之间,分离到的菌株对咪鲜胺均表现为中抗和高抗,其中中抗菌株18株,占23.38%,高抗菌株59株,占76.62%,说明咪鲜胺高抗菌株已经成为江苏省的恶苗病菌优势群体。氰烯菌酯(JS399-19)对水稻恶苗病菌的EC50值在0.012~2.040μg/m L之间,菌株的敏感性频率近似正态分布,EC50均值为(0.684±0.265)μg/m L,建议将此值作为江苏省水稻恶苗病菌对氰烯菌酯的敏感性基线。     

药剂对稻曲病菌的毒力测定及复配研究

为筛选防治稻曲病的有效单剂和复配组合,采用菌丝生长速率法,测定烯唑醇、腈菌唑、丙环唑、咪鲜胺、苯菌灵、多菌灵、戊唑醇、井冈霉素、松脂酸铜9种杀菌剂及互相复配后对稻曲病菌的毒力,并比较了不同复配组合的协同作用.结果表明:稻曲病菌对烯唑醇最敏感,EC5o为0.145 μg/mL;井冈霉素对稻曲病菌的毒力作用最弱,EC50为13.6 μg/mL.从252种不同比例复配的药剂中,筛选出12种增效配方,其中烯唑醇和咪鲜胺复配(1∶10),协同系数高达3.70,增效作用最大;烯唑醇和咪鲜胺(1∶10)对稻曲病菌的毒力作用最强,EC5o为0.06μg/mL,其次是烯唑醇和咪鲜胺(1∶20)与烯唑醇和腈菌唑(10∶1),EC50分别为0.10μ/mL和0.11μg/mL.田间试验结果也表明:烯唑醇与咪鲜胺(1∶10)复配,对稻曲病的平均防效为79.2％,高于其他常用药剂.     

Development of apothecia ofTapesia yallundae in contrasting populations selected by fungicides

Apothecia of the eyespot fungus,Tapesia yallundae, were found on 0–18% of straws in plots of wheat stubble in February–March 1994. The fungicides carbendazim, prochloraz or carbendazim plus prochloraz had been applied repeatedly to the same plots in each of the previous 9 years in which successive wheat crops had been grown. The factors most strongly correlated with the incidence of apothecia were the incidence and severity of eyespot in the preceding wheat crop and the frequency of carbendazim-resistant W-type fungus in populations recovered from that wheat crop. Plots treated with carbendazim, which had previously had more disease and more resistance to carbendazim in the pathogen population relative to untreated plots, therefore yielded most apothecia. Plots treated with prochloraz, which had selected for predominantly R-type fungus and decreased eyespot, yielded few apothecia. Single-ascospore isolates were all of the W-type and were more frequently carbendazim-sensitive than expected, except those from plots treated only with carbendazim. None showed decreased sensitivity to prochloraz. The implications of applying fungicides regularly for controlling eyespot on the capability of the eyespot fungus for genetic variation through sexual reproduction are discussed.     

Influence of spray programmes on development of fungicide resistance in the eyespot pathogen of wheat, Pseudocercospovella herpotrichoides

A site with no known history of cereal growing or carbendazim fungicide use was inoculated in 1983 with an equal mixture of spores of R-type and W-type isolates of Pseudocercosporella herpotrichoides. all sensitive to carbendazim. Following three consecutive years of carbendazim sprays, more than 90% of isolates recovered were carbendazim-resistant. A majority of R-type isolates was recovered after 3 years and resistance was found to be more frequent in R-type than in W-type isolates. A mixture of carbendazim with prochloraz initially delayed the development of carbendazim resistance, but after 3 years the incidence of resistance was similar to that where carbendazim alone was applied. The best control of eyespot was given by the mixture and by a split application of prochloraz in the first year, by the mixture in the second year, and by the split prochloraz application in the final year. A greater proportion of R-type isolates was recovered from prochloraz-treated plots than from unsprayed plots; the proportion of these that were resistant to carbendazim was lower than that from carbendazim treatments. Throughout this study isolates resistant to prochloraz were not detected.     

荸荠枯萎病发生动态及防治技术

荸荠枯萎病在我国各个荸荠Eleocharis dulcis产区普遍发生,是影响荸荠产量的重要病害。为有效防治该病害,于2010—2012年调查了湖北省荸荠枯萎病的田间发生动态,并进行了荸荠品种抗病性评价、室内药剂筛选及药剂处理球茎盆栽和田间试验。3年田间病情调查结果表明,荸荠枯萎病于8月中旬开始发生,8下旬—9月上旬温度适宜,病害开始缓慢增长;9月下旬—10月中旬为该病发生的高峰期;病情指数均与温度呈显著负相关,但各年份的病情指数与相对湿度和降雨量均无显著相关性。沙洋荠、肇庆荠、韶关马坝荠、桂林荠-1品种对荸荠枯萎病有较强的抗性。10%苯醚甲环唑、25%多菌灵、40%氟硅唑和25%嘧菌酯4种药剂处理球茎均有利于荸荠出苗。经多菌灵和氟硅唑处理的球茎假植到大田2个月后对荸荠枯萎病仍有一定的防治效果,防治效果分别为22.3%和27.0%,而嘧菌酯和苯醚甲环唑对该病基本无防治效果。     

Synergism between EBI fungicides and a pyrethroid insecticide in the honeybee (Apis mellifera)

The synergistic effect of a range of ergosterol-biosynthesis-inhibiting (EBI) fungicides and a pyrethroid insecticide was studied in the honeybee (Apis mellifera L.). Various EBI fungicides were combined separately with the pyrethroid lambda-cyhalothrin at ratios derived from their recommended application rates to represent tank-mixing in the field. The mixture was then applied topically to the thorax of honeybees, and mortality assessed 24 h post-treatment. All the fungicides tested increased the toxicity of lambda-cyhalothrin to honeybees. The fungicide propiconazole was found to have the strongest synergistic effect, decreasing the LD₅₀ of lambda-cyalothrin from 68.0 ng bee^?1 to 4.2 ng, thus having a synergistic ratio of 16.2. Hazard ratios were calculated for lambda-cyhalothrin and fungicide mixtures using a recommended application rate of 7.5 g a.i. ha^?1. The hazard ratio for lambda-cyhalothrin alone was 110, but when mixed with fungicide synergists, the hazard ratio ranged from 366 with flutriafol to 1786 with propiconazole. A blank formulation of a fungicide (without the active ingredient prochloraz) had little effect on the toxicity of lambda-cyhalothrin, indicating that it is primarily the fungicide active ingredient that is responsible for the synergistic effect. The results are discussed in terms of the potential hazard posed by pesticide synergism to honeybees in the field.     

湖北省小麦赤霉病菌对多菌灵、戊唑醇和咪鲜胺的敏感性

对2014年采自中国湖北省7个县、市的206株小麦赤霉病菌样品进行单孢分离与鉴定,并采用菌丝生长速率法随机测定了其中100株菌株对多菌灵、戊唑醇和咪鲜胺的敏感性,建立了其敏感基线。结果表明:多菌灵、戊唑醇和咪鲜胺对湖北省小麦赤霉病菌的EC50值范围分别为0.115~0.705、0.006~1.356和0.002~0.370 μg/mL,平均值分别为0.248、0.181和0.040 μg/mL;供试100株小麦赤霉病菌对3种药剂的敏感性频率均呈单峰拟正态分布,因此可将所得各EC50平均值分别作为湖北省小麦赤霉病菌对3种药剂的敏感基线参考值。以各药剂EC50平均值的10倍作为敏感性鉴别浓度,对2015及2016年湖北省小麦赤霉病菌的敏感性进行了监测,在该鉴别浓度下,多菌灵、戊唑醇和咪鲜胺对2015年小麦赤霉病菌的平均抑制率分别为100%、85.14%和82.35%,对2016年小麦赤霉病菌的平均抑制率分别为100%、76.67%和73.62%。研究表明,虽然戊唑醇和咪鲜胺对2016年小麦赤霉病菌的抑制率略有下降,但整体而言,湖北省小麦赤霉病菌对多菌灵、戊唑醇及咪鲜胺仍具有较高的敏感性。     

A mini-bag technique for evaluation of fungicide effects on Trichoderma spp in mushroom compost

An in vivo technique was developed to observe colonisation of mushroom compost by Trichoderma spp. Isolates of T. harzianum (Th2), T. harzianum (Th1), T. koningii (Tk) and T. viride (Tv) were artificially introduced into compost using a mini-bag system. Wheat grains, colonised by Trichoderma spp, were placed centrally on a layer of compost at the bottom of 1-litre polythene bags which were then filled with 350 g of spawned or un-spawned compost, and partially sealed. After 14 and 21 days incubation at 27 degrees C, the bags were assessed for recovery of Trichoderma from middle and top zones using a needle stab re-isolation technique and a visual colonisation scoring system. Visible green mould contamination, similar to that observed in practice, developed within 21 days. The visual colonisation scoring was reliably related to the re-isolation success. In this evaluation, Trichoderma spp showed considerable differences in their relative abilities to colonise spawned and un-spawned compost, with Th2 isolates being consistently superior to the other isolates of Th1, Tk and Tv in colonising spawned compost. This technique was employed to evaluate the effects of fungicides on the colonisation of mushroom compost by three Trichoderma spp: Th2, Th1 and Tk, using 1-litre and 5-litre mini-bag systems. Aqueous suspensions of benomyl, carbendazim, thiabendazole, prochloraz and prochloraz+carbendazim incorporated into the compost at 50 mg litre(-1), or applied to spawn at 50 mg kg(-1), reduced the colonisation by Trichoderma spp. Prochloraz and prochloraz+carbendazim were superior to benomyl, carbendazim or thiabendazole in reducing compost colonisation by Th2, Th1 and Tk, with Th2 being the most persistent type, capable of colonising treated compost in the presence of all five fungicides. The prochloraz+carbendazim mixture, not normally used in mushroom production, was equal to or better than prochloraz alone. The incidence of green mould colonisation by Th2 was as extensive in the 5-litre compost bags as in the 1-litre bags, but colonisation by Th1 and Tk was more apparent in the 5-litre bags. The in vivo mini-bag evaluations using wheat grain Trichoderma inoculum and needle stab re-isolation procedures proved an efficient method for studying colonisation and screening for effectiveness of fungicides applied to mushroom compost or spawn.