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Wieczorek T.M.,University of Aarhus | Berg G.,Plant Protection Center | Semaskiene R.,Lithuanian Research Center for Agriculture and Forestry | Mehl A.,Bayer CropScience | And 4 more authors.
European Journal of Plant Pathology | Year: 2015

Zymoseptoria tritici is a dominant pathogen in wheat causing Septoria leaf blotch (SLB), and sterol 14α-demethylation inhibitors fungicides (DMI) are commonly used for control in Northern Europe. In 14 winter wheat trials carried out in Denmark, Lithuania, and Sweden in the years 2011 to 2013, fungicides containing DMIs were investigated for their efficacy and impact on CYP51 mutations in Z. tritici populations. All fungicide treatments were applied twice – each time using 50 % of the standard rate, applied at GS 37 & 55. The single-agent DMIs, epoxiconazole and prothioconazole and a mixture of difenoconazole + propiconazole gave similar control and crop yields. The best solution varied among localities. Adding prochloraz to prothioconazole as well as using co-formulations of DMIs + SDHIs generally improved control compared with using DMIs alone. Yield responses were significant from all treatments, but co-formulations of DMIs plus SDHIs increased yield the most. Specific CYP51 mutations in Z. tritici were analysed by pyrosequencing and qPCR. Their frequency varied across sites and countries. The amount of I381V was high in all trials whereas the amount of A379G was moderate. Levels of D134G, V136C, and S524T were low to moderate across all sites. DMIs and mixtures of DMIs + SDHI selected differently for CYP51 mutations. Prochloraz increased selection for D134G and V136A and decreased selection for A379G and I381V. The lowest selection pressure towards D134G and V136A/C was recorded in the presence of the mixture difenoconazole and propioconazole. Mixtures of DMIs and SDHI tended to lower the frequency of V136A/C compared to DMIs used alone but had no measurable impact on the frequency of I381V and A379G. No responses were seen in relation to S524T, which only occurred at a very low level. © 2015, Koninklijke Nederlandse Planteziektenkundige Vereniging. Source


Jorgensen L.N.,University of Aarhus | Hovmoller M.S.,University of Aarhus | Hansen J.G.,University of Aarhus | Lassen P.,University of Aarhus | And 13 more authors.
Journal of Integrative Agriculture | Year: 2014

Information about disease management in winter wheat (Triticum aestiva) in eight European countries was collated and analysed by scientists and extension workers within the European Network for the Durable Exploitation of Crop Protection Strategies (ENDURE). This included information about specific disease thresholds, decision support systems, host varieties, disease prevalence and pathogen virulence. Major differences in disease prevalence and economic importance were observed. Septoria tritici blotch (Mycosphaerella graminicola) was recognized as the most yield reducing disease in countries with intensive wheat production, but also rust diseases (Puccinia striiformis and Puccinia triticina), powdery mildew (Blumeria graminis) and Fusarium head blight (Fusarium spp.) were seen as serious disease problems. Examples of current integrated pest management (IPM) strategies in different countries have been reported. Disease management and fungicide use patterns showed major differences, with an average input equivalent to 2.3 full dose rates (TFI) in the UK and a TFI of 0.6 in Denmark. These differences are most likely due to a combination of different cropping systems, climatic differences, disease prevalence, and socio-economic factors. The web based information platform www.eurowheat.org was used for dissemination of information and results including information on control thresholds, cultural practices which can influence disease attack, fungicide efficacy, fungicide resistance, and pathogen virulence, which are all elements supporting IPM for disease control in wheat. The platform is open to all users. The target groups of Euro Wheat information are researchers, advisors, breeders, and similar partners dealing with disease management in wheat. © 2014 Chinese Academy of Agricultural Sciences. Source


Nauen R.,Bayer CropScience | Zimmer C.T.,Bayer CropScience | Zimmer C.T.,University of Hohenheim | Andrews M.,Syngenta | And 8 more authors.
Pesticide Biochemistry and Physiology | Year: 2012

Pollen beetle, . Meligethes aeneus F. (Coleoptera: Nitidulidae) is a major univoltine pest of oilseed rape in many European countries. Winter oilseed rape is cultivated on several million hectares in Europe and the continuous use of pyrethroid insecticides to control pollen beetle populations has resulted in high selection pressure and subsequent development of resistance. Resistance to pyrethroid insecticides in this pest is now widespread and the levels of resistance are often sufficient to result in field control failures at recommended application rates. Recently, metabolic resistance mediated by cytochrome P450 monooxygenases was implicated in the resistance of several pollen beetle populations from different European regions. Here, we have also investigated the possible occurrence of a target-site mechanism caused by modification of the pollen beetle . para-type voltage-gated sodium channel gene. We detected a single nucleotide change that results in an amino acid substitution (L1014F) within the domain IIS6 region of the channel protein. The L1014F mutation, often termed . kdr, has been found in several other insect pests and is known to confer moderate levels of resistance to pyrethroids. We developed a pyrosequencing-based diagnostic assay that can detect the L1014F mutation in individual beetles and tested more than 350 populations collected between 2006 and 2010 in 13 European countries. In the majority of populations tested the mutation was absent, and only samples from two countries, Denmark and Sweden, contained pollen beetles heterozygous or homozygous for the L1014F mutation. The mutation was first detected in a sample from Denmark collected in 2007 after reports of field failure using . tau-fluvalinate, and has since been detected in 7 out of 11 samples from Denmark and 25 of 33 samples from Sweden. No super-. kdr mutations (e.g. M918T) known to cause resistance to pyrethroids were detected. The implications of these results for resistance management strategies of pollen beetle populations in oilseed rape crops are discussed. © 2012 Elsevier Inc.. Source


Vongphachan P.,Plant Protection Center | Villalta C.F.,University of California at San Francisco | Songvilay P.,Plant Protection Center | Chittarhath K.,Plant Protection Center | And 3 more authors.
Australasian Plant Disease Notes | Year: 2013

A major problem with contamination of fungal and bacterial cultures by Neurospora in the diagnostic laboratory of the Plant Pathology Unit at the Plant Protection Centre in Vientiane, Laos, occurred in May 2009 and again in April-May 2010. The problem persisted despite sterilization of all contaminated cultures and stringent disinfection procedures. Initial attempts to identify the source were unsuccessful. However in May 2010 the senior author realised that the orange fungus common on old sticky rice in traditional baskets was Neurospora. A limited survey indicated that this was a key source of conidia in the precinct around the laboratory, and elsewhere in Vientiane. A sample was collected and forwarded to the second author at the Plant and Microbial Biology Department in the University of California, Berkeley, California, USA, for confirmation of the genus, and identification of the species. It was identified as N. intermedia (Tai Mycologia 27:289-294 1935), and the isolate used in the phylogenetic study was deposited in the Fungal Genetics Stock Centre as FGSC10868. This is the first report of a Neurospora species in Lao. © 2012 Australasian Plant Pathology Society Inc. Source


Songvilay P.,Plant Protection Center | Groenewald J.Z.,Fungal Biodiversity Center | Vongphachanh P.,Plant Protection Center | Sayapattha S.,Plant Protection Center | And 3 more authors.
Australasian Plant Disease Notes | Year: 2013

In May 2010 basal stem rot of snake bean (long bean) (Vigna unguiculata subsp. sesquipedalis) caused by Sclerotium rolfsii was discovered in Vientiane Capital, Lao PDR, during an ad hoc disease survey. The disease had resulted in death of some infected plants. The basal stem region had a bleached appearance, a typical symptom of this disease. Abundant small, round, brown sclerotia were present on the stem base, and on the adjacent soil and dead leaf material. The fungus was isolated into pure culture and Koch's postulates were fulfilled. This is the first report of S. rolfsii in the Lao PDR, and the first report of basal stem rot of snake bean caused by this pathogen in the Lao PDR. © 2012 Australasian Plant Pathology Society Inc. Source

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