Effects of fungicides on in vitro spore germination and mycelial growth of the phytopathogens Leptosphaeria maculans and L. biglobosa (phoma stem canker of oilseed rape)

BACKGROUND: Phoma stem canker, caused by the coexisting related fungal pathogens Leptosphaeria maculans (Des.) Ces. & de Not and L. biglobosa Shoemaker & H Brun, is a major disease of winter oilseed rape in the UK. Annually, over 90% of UK crops receive at least one foliar application of fungicide, but little is known about the sensitivity of the more damaging L. maculans and the less damaging L. biglobosa to these fungicides. The effects of flusilazole, tebuconazole and Methyl Benzimidazole Carbamate (MBC) fungicides (benomyl and carbendazim) on the germination of ascospores, conidia and germ tube growth of both species were examined. Isolates collected from different oilseed rape crops in England and Wales were assessed for their mycelial growth on fungicide‐amended medium, and ED₅₀ values were calculated. RESULTS: Leptosphaeria maculans and L. biglobosa differed in their sensitivity to fungicides. Conidial germination of L. maculans was more sensitive to these fungicides than that of L. biglobosa. Isolates of L. maculans had smaller ED₅₀ values for mycelial growth for all fungicides tested than isolates of L. biglobosa. CONCLUSION: These results suggest that fungicide applications might affect the structure of L. maculans/L. biglobosa populations in UK winter oilseed rape crops. Copyright © 2009 Society of Chemical Industry     

Transfer of the β‐tubulin gene of Botrytis cinerea with resistance to carbendazim into Fusarium graminearum

BACKGROUND: Resistance to carbendazim and other benzimidazole fungicides in Botrytis cinerea (Pers. ex Fr.) and most other fungi is usually conferred by mutation(s) in a single chromosomal β‐tubulin gene, often with several allelic mutations. In Fusarium graminearum Schwade, however, carbendazim resistance is not associated with a mutation in the corresponding β‐tubulin gene. RESULTS: The β‐tubulin gene conferring carbendazim resistance in B. cinerea was cloned and connected with two homologous arms of the β‐tubulin gene of F. graminearum by using a double‐joint polymerase chain reaction (PCR). This fragment was transferred into F. graminearum via homologous double crossover at the site where the β‐tubulin gene of F. graminearum is normally located (the β‐tubulin gene of F. graminearum had been deleted). The transformants were confirmed and tested for their sensitivity to carbendazim. CONCLUSION: The β‐tubulin gene conferring carbendazim resistance in B. cinerea could not express this resistance in F. graminearum, as transformants were still very sensitive to carbendazim. Copyright © 2010 Society of Chemical Industry     

Pyraclostrobin reduces germ tube growth of QoI‐resistant Mycosphaerella graminicola pycnidiospores and the severity of septoria tritici blotch on winter wheat

The effect of the quinone outside inhibitors (QoI) azoxystrobin and pyraclostrobin on yields of winter wheat where QoI resistant Mycosphaerella graminicola isolates were dominant was investigated in field trials in 2006 and 2007. Pyraclostrobin significantly increased yields by 1·57 t ha^?1 in 2006 and 0·89 t ha^?1 in 2007 when compared to the untreated controls, while azoxystrobin only provided a significant increase of 1·28 t ha^?1 in 2006. These yield increases were associated with reduction in septoria tritici blotch (STB) development as determined by weekly disease assessments over a 7 week interval. The effect of pyraclostrobin on STB was studied in controlled environment experiments using wheat seedlings inoculated with individual M. graminicola isolates. Pyraclostrobin significantly reduced STB symptoms by up to 62%, whether applied 48 h pre‐ or post‐ inoculation with resistant M. graminicola isolates containing the cytochrome b mutation G143A. Extremely limited disease (<1%) was observed on similarly treated seedlings inoculated with an intermediately resistant isolate containing the cytochrome b mutation F129L, while no disease was observed on seedlings inoculated with a wild‐type isolate. Germination studies of pycnidiospores of M. graminicola on water agar amended with azoxystrobin or pyraclostrobin showed that neither fungicide inhibited germination of spores of resistant isolates containing the mutation G143A. However, pyraclostrobin significantly reduced germ tube length by up to 46% when compared with the untreated controls. Although the QoIs can no longer be relied upon to provide effective M. graminicola control, this study provides an insight into why QoIs still provide limited STB disease control and yield increases even in situations of high QoI resistance.     

大蒜叶枯病防治初步研究

选用7种低毒广谱杀菌剂,对大蒜叶枯病进行了田间药效试验。试验表明：每666．7m^2用25％阿米西达悬浮剂20g．50％翠贝干悬浮剂10g和26．26％万兴乳油24ml,可有效防治大蒜叶枯病。     

花生疮痂病的药剂防治

采用70%甲基托布津可湿性粉剂、10%苯醚甲环唑可湿性粉剂、50%多菌灵可湿性粉剂、70%代森锰锌可湿性粉剂、30%爱苗乳油、75%百菌清可湿性粉剂、50%速克灵可湿性粉剂和苯醚甲环唑.多菌灵等8种药剂对花生疮痂病进行防治试验,结果表明：几种药剂均有一定的防治效果,其中70%甲基托布津可湿性粉剂和10%苯醚甲环唑可湿性粉剂的防治效果最好,单株结荚数多,果饱、果大,增产幅度最大;70%代森锰锌可湿性粉剂防治效果最差,增产幅度最小。     

几种杀菌剂防治甜菜褐斑病效果分析

[目的]筛选出防治甜菜褐斑病(Cercoapora belicola Sacc.)效果较好的杀菌剂为该病的有效防治提供理论依据.[方法]选择5种杀菌剂,进行防治甜菜褐斑病的田间小区试验.[结果]筛选出防治效果较好的杀菌剂是福星5000倍液和氟硅唑·多菌灵(12.5;·27.5;)悬浮剂,防效分别为60.80;和58.37;.与其他杀菌剂有显著性差异.5种杀菌剂防治时应连续喷药,间隔期7d,连续施药2次.I结论]5种杀菌剂均对甜菜褐斑病有一定的防治效果,防效最高的杀菌剂是福星、氟硅唑·多菌灵,可在生产上推广应用.     

不同杀菌剂及混剂对番茄灰霉病菌的室内抑制效果研究

[目的]筛选高效、低毒的番茄灰霉病杀菌剂,缓解和治理其抗药性.[方法]在室内离体条件下,采用生长速率法及抑制孢子萌发法测定了几种杀菌剂对番茄灰霉病菌的敏感性.[结果]30;爱苗、50;福美双、40;施灰乐、50;扑海因,对病原菌菌丝生长的EC_(50)值在0.347 6～0.724 2 μg/mL,均小于1 μg/mL,番茄灰霉病菌对上述杀菌剂均处于比较敏感的阶段;50;农利灵和65;乙霉威的EC_(50)均大于1 μg/mL,敏感程度相对较低.孢子萌发试验中,30;爱苗、50;福美双、50;扑海因对番茄灰霉菌孢子萌发的抑制活性高,EC_(50)值在1.308 5～1.336 4 μg/mL;50;农利灵和40;施灰乐的抑制活性次之,EC_(50)分别为1.525 4和1.777 4 μg/mL;65;乙霉威的抑制活性相对较低,EC_(50)为2.173 8 μg/mL.[结论]将不同作用机理的杀菌剂50;扑海因与50;福美双以1∶1和1∶2的比例混配,联合毒力测定和评价结果表明相互作用为增效.     

打瓜白粉病的发生及化学药剂防治试验

打瓜白粉病是打瓜上最严重病害之一,给生产带来了严重影响.探讨白粉病的发生特点、防治具有很重要的意义.2008年通过调查得出,福海县打瓜白粉病的发病初期为7月初,气候条件适宜时,7月底8月初瘸害达到高峰值,发病率可达100;,发生面积广,危害程度重.2007年通过药剂筛选试验,筛选出防治效果较好的药剂为福星、敌力康,防治效果达77.02;、73.90;.因此,控制好打瓜白粉病的严重危害,必须抓住防治关键时期,于病害发生前期,即6月底7月初进行喷药预防,以后每隔7～10 d喷药防治一次,喷3～6次,可以取得好的防治效果.     

六种杀菌剂对向日葵白锈病的田间防治效果

六种药剂对向日葵白锈病的田间防效试验结果表明:25;甲霜灵WP 1 000倍液、50;安克WG 2 500倍液的防效较高,分别为87.6;和86.8;;显著优于防效次之的64;杀毒矾WP 800倍液(防效75.7;)和其他3种杀菌剂.52.5;抑快净WG 1 000倍、72;霜疫必克WP 600倍和80;乙磷铝WP 600倍的防效相当,均未达到50;,是供试药剂中防效较低的3种杀菌剂.经方差分析三者间差异显著.     

PS04菌株的抗真菌活性

前一阶段分离得到1株具有抗真菌活性的细菌菌株PS04,室内测定结果表明,该菌株培养物乙醇抽提物对水稻纹枯病、稻瘟病等多种植物病害的病原真菌具有抗菌活性,对水稻纹枯病病原的抑制中浓度为99.4μg/mL,作用于植物病原真菌,导致菌丝畸形,菌丝体节间缩短,菌丝体顶端分枝增多。该抑菌活性物质稳定性好,在温度40~100℃,pH6.2~7.0范围内稳定。