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Disease symptoms of Septoria pyricola on pear: a, spots on leaves; b, pycnidia (×10) on a leaf spot; c, lesions on fruit.
Source publication
The sensitivity of 36 Septoria pyricola single spore isolates, obtained from isolated pear orchards, to carbendazim, bitertanol, flusilazole, myclobutanil, azoxystrobin, kresoxim-methyl, pyraclostrobin, trifloxystrobin and boscalid, was studied in vitro. Spore suspensions were point-inoculated on media amended with various concentrations of fungici...
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Citations
... inhibitory effect on nitrogen fixers, nitrifying bacteria and cellulolytic organisms (Fawole et al., 2009). Few isolates of Septoriapyricola failed to form colonies with Carbendazim concentration 0.1 to 10 mg.L -1 (Pappas et al., 2010). At 0.02, 0.5 and 1ppm concentration of Captan, 22 isolates were screened, out of them one isolateCTG-10 showed sensitivity at 1 ppm concentration of Captan (Plate 2). ...
... On the basis of spore germination and mycelial growth tests, the discriminatory doses to assess the various sensitivity levels were determined and used for screening an additional three hundred and eighteen (318) isolates by the point inoculation method [28]. In brief, a drop (about 20 μL) of a dense spore suspension in sterile water (about 50,000 spores per mL) of each isolate was pipetted on pre-marked points on the periphery of Petri dishes containing MEA medium amended with the MICs for the sensitive isolates of each fungicide. ...
The excessive use of fungicides against Venturia inaequalis, the causal agent of apple scab, has led to the emergence of resistant populations to multiple fungicides over the years. In Greece, there is no available information on fungicide resistance, despite the fact that control failures have been reported on certain areas. An amount of 418 single-spore isolates were collected from three major apple production areas and tested for their sensitivity to eight commonly used fungicides from unrelated chemical groups. The isolates were tested on malt extract agar media enriched with the discriminatory dose of each fungicide using the point inoculation method. To define the discriminatory dose for assessing the levels of resistance, EC50 values on both spore germination and mycelial growth assays were previously determined. Isolates exhibiting high resistance to trifloxystrobin (92% in total) and difenoconazole (3%); and moderate resistance to cyprodinil (75%), dodine (28%), difenoconazole (36%), boscalid (5%), and fludioxonil (7%) were found for the first time in Greece. A small percentage of the isolates were also found less sensitive to captan (8%) and dithianon (6%). Two isolates showed various levels of resistance to all eight fungicides. Despite the occurrence of strains with multiple resistances to many fungicides, we concluded that this practical resistance in the field arose mainly due to the poor control of apple scab with trifloxystrobin and difenoconazole.
... Os fungicidas foram dissolvidos em água destilada esterilizada para obtenção de solução estoque. A partir desta foram feitas diluições em série para obtenção das concentrações de 0,1; 1,0; 10; 100 e 1000 mg L -1 em 100 mL de meio BDA fundente (45 a 47 °C), similar ao método descrito por (RUSSEL 2008, PAPPAS et al. 2010 Uma alíquota de 0,1 mL de suspensão de conídios foi depositada em lâminas de vidro para microscopia que continham uma película de BDA suplementado com 0; 0,1; 1,0; 10; 100 e 1000 mg L -1 de ingrediente ativo dos fungicidas mancozeb e tiofanato metílico e pressionado suavemente com a alça de Drigalski para a quebra da tensão superficial da gota (RUSSEL 2008). Tiras de papel celofane esterilizadas de igual dimensão foram colocadas sobre as lâminas para auxiliar na indução da germinação dos conídios e mantidas à 24 ± 2 o C, com fotoperíodo de 12 horas. ...
... Tabela 3. Fator de redução de sensibilidade (FRS) dos fungicidas mancozeb e tiofanato metílico para isolados de Septoria lycopersici proveniente de lavoura sem aplicação de fungicida, em relação ao isolado 475-3. Nos últimos anos, a resistência de fungicidas tem sido motivo de preocupação para muitos grupos de patógenos, incluindo espécies de Septoria (PAPPAS et al. 2010, ESTEP et al. 2015, ISHII & HOLLOMAN 2015. ...
A septoriose é uma das principais doenças do tomateiro e os prejuízos causados variam em função da área cultivada com cultivar suscetível, raças fisiológicas do patógeno e condições climáticas. O objetivo do estudo foi determinar a dose efetiva na inibição de 50% da germinação de esporos (DE50), avaliar o fator de redução de sensibilidade (FRS) de isolados de Septoria lycopersici e a eficiência de fungicidas tradicionalmente utilizados no controle da septoriose do tomateiro em Santa Catarina, durante as safras 2016 e 2017. Nos experimentos in vitro, 13 isolados de S. lycopersici obtidos de folhas com sintomas de septoriose do tomateiro de diferentes cultivares e os fungicidas tiofanato metílico e mancozeb nas concentrações de 0,1; 1,0; 10; 100 e 1000 mg L-1 do ingrediente ativo (i.a), foram avaliados para determinar a dose efetiva na inibição de 50% da germinação de esporos (DE50) e o fator de redução de sensibilidade (FRS). Os isolados provenientes de lavouras que receberam aplicações de fungicidas foram comparados com os isolados 475-1, 475-3, 475-4 e 475-7 proveniente de lavouras que não receberam aplicações de fungicidas. Nos experimentos in vivo, os fungicidas preventivos azoxistrobina, clorotalonil, captana e mancozeb e os curativos tiofanato metílico, mancozeb, difenoconazol e metconazol nas doses comerciais foram pulverizados 12, 24, 36, 48, 72 e 96 h antes (preventivo) e após (curativo) à inoculação do isolado 475-1 de S. lycopersici para avaliar a eficiência no controle da septoriose do tomateiro. Os ingredientes ativos tiofanato metílico e mancozeb, independente das doses testadas, foram atóxicos aos 13 isolados de S. lycopersici. Os valores de DE50 do tiofanato metílico e mancozeb para a inibição da germinação dos conídios variaram entre 75 e 580 mg L-1. Os fungicidas preventivos clorotalonil, azoxistrobina e os curativos difenoconazol e metconazol foram significativamente eficientes no controle da septoriose do tomateiro in vivo.
... Krystalli (Biris et al., 1991;Pappas et al., 2006), leaf epidemics are commonly occurring, which may cause premature defoliation. Until recently, the incidence of infections on fruit in Greece was little known but within the last few years serious outbreaks have arisen (Pappas et al., 2010;Thomidis and Katerinis, 2014). The pathogen causes superficial spots on fruits, usually without bearing pycnidia, which decrease their quality and shelf life. ...
... Laboratory studies on sensitivity of S. pyricola isolates to several fungicides used against pear scab, verified the high frequency of resistance to carbendazim. Some isolates exhibited also reduced sensitivity to three DMI's, whereas all of them were found sensitive to four QoI fungicides and to boscalid of the SDHI group (Pappas et al., 2010). ...
... For all tests, pycnidiospores obtained from fresh subcultures grown on PDA for 2 weeks and incubated at 24°C in the dark, were used as inoculum. A single spore carbendazim-sensitive (M-1) and one-highly resistant (E-1) isolate (Pappas et al., 2010), were used in artificial inoculations. ...
The susceptibility of pear leaf and fruit at their early development stages to Septoria pyricola and the chemical control of the disease were studied. Unfolded or fully expanded leaves and young fruit were susceptible to infections,when artificially inoculated. With an average temperature of 14°C,relative humidity of 70% and increased leaf wetness for at least 6 hours during the night,the characteristic disease symptoms,on both leaves and fruits,were developed within two to three weeks. Pycnidia were not formed on fruit and their infection was confirmed by applying Koch’s postulates. Surveys in pear orchards during 2010 revealed the predominance of isolates highly resistant to the benzimidazole fungicide carbendazim. Some isolates exhibited 10-fold reduced sensitivity to bitertanol (sterol demethylation inhibitors; DMI’s) but they were sensitive to kresoxim-methyl (quinone outside inhibitors; QoI’s) and to boscalid (succinate dehydrogenase inhibitors; SDHI’s). Bitertanol and flusilazole (DMI’s),azoxystrobin,kresoxim-methyl and trifloxystrobin (QoI’s) and the mixture of pyraclostrobin (QoI) plus boscalid (SDHI) controlled Septoria effectively when they were applied on five occasions,commencing at the stage of ‘inflorescence emergence’. The disease progress was ceased even in cases of only one application with either azoxystrobin or flusilazole at ‘inflorescence emergence’ stage. Carbendazim failed to control the disease when BenHR-resistant propagules were enclosed in the primary inoculum. The results indicate that the pear leaf and fruit are vulnerable to S. pyricola at early stages of development,whereas secondary formed inocula on leaves expanded the disease only within the tree canopy.
Maize is a socioeconomically important crop in many countries. Recently, a high incidence of stalk rot disease has been reported in several maize fields in Gangwon province. In this report, we show that maize stalk rot is associated with the fungal pathogens Fusarium subglutinans and F. temperatum. Since no fungicides are available to control these pathogens on maize plants, we selected six fungicides (tebuconazole, difenoconazole, fluquinconazole, azoxystrobin, prochloraz and kresoxim-methyl) and examined their effectiveness against the two pathogens. The in vitro antifungal effects of the six fungicides on mycelial growth and colony formation were investigated. Based on the inhibition of mycelial growth, the most toxic fungicide was tebuconazole with 50% effective concentrations (EC50) of <0.1 μg/ml and EC90 values of 0.9 μg/ml for both pathogens, while the least toxic fungicide was azoxystrobin with EC50 values of 0.7 and 0.5 μg/ml for F. subglutinans and F. temperatum, respectively, and EC90 values of >3,000 μg/ml for both pathogens. Based on the inhibition of colony formation by the two pathogens, kresoxim-methyl was the most toxic fungicide with complete inhibition of colony formation at concentrations of 0.1 and 0.01 μg/ml for F. subglutinans and F. temperatum, respectively, whereas azoxystrobin was the least toxic fungicide with complete inhibition of colony formation at concentrations >3,000 μg/ml for both pathogens.
Maize is a socioeconomically important crop in many countries. Recently, a high incidence of stalk rot disease has been reported in several maize fields in Gangwon province. In this report, we show that maize stalk rot is associated with the fungal pathogens Fusarium subglutinans and F. temperatum. Since no fungicides are available to control these pathogens on maize plants, we selected six fungicides (tebuconazole, difenoconazole, fluquinconazole, azoxystrobin, prochloraz and kresoxim-methyl) and examined their effectiveness against the two pathogens. The in vitro antifungal effects of the six fungicides on mycelial growth and colony formation were investigated. Based on the inhibition of mycelial growth, the most toxic fungicide was tebuconazole with 50% effective concentrations (EC50) of <0.1 µg/ml and EC90 values of 0.9 µg/ml for both pathogens, while the least toxic fungicide was azoxystrobin with EC50 values of 0.7 and 0.5 µg/ml for F. subglutinans and F. temperatum, respectively, and EC90 values of >3,000 μg/ml for both pathogens. Based on the inhibition of colony formation by the two pathogens, kresoxim-methyl was the most toxic fungicide with complete inhibition of colony formation at concentrations of 0.1 and 0.01 μg/ml for F. subglutinans and F. temperatum, respectively, whereas azoxystrobin was the least toxic fungicide with complete inhibition of colony formation at concentrations >3,000 μg/ml for both pathogens.
