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Fungicides
Kinds of Fungicides Terms modified by Fungicides Selected AbstractsBiological warfare in the garden pond: tadpoles suppress the growth of mosquito larvaeECOLOGICAL ENTOMOLOGY, Issue 1 2003Allie Mokany Abstract. 1. Although tadpoles and mosquito larvae may compete for scarce resources in natural freshwater systems, the mechanisms involved in such competition remain largely unstudied. 2. Replicated artificial ponds were set up to examine the role of pathogenic interference (water-borne growth inhibitors) in two tadpole,mosquito systems from south-eastern Australia. One system comprised taxa that are commonly sympatric in freshwater ponds (tadpoles of Limnodynastes peronii and larvae of Culex quinquefasciatus) while the other comprised species that co-occur in brackish water ponds (tadpoles of Crinia signifera and larvae of Ochlerotatus australis). 3. Water that had previously contained tadpoles suppressed the rates of survival and pupation of mosquito larvae in both systems. Fungicide reduced or eliminated this effect, suggesting that the growth inhibitors may be fungal organisms (possibly the yeast Rhodotorula glutinis) from tadpole faeces. Fungicide also enhanced growth rates of tadpoles. 4. These results suggest that interference competition between tadpoles and mosquito larvae is mediated by other organisms in some ecological systems. [source] Review of the validation of models used in Federal Insecticide, Fungicide, and Rodenticide Act Environmental exposure assessmentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2002Russell L. Jmones Abstract The first activity of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Environmental Model Validation Task Force, established to increase confidence in the use of environmental models used in regulatory assessments, was to review the literature information on validation of the pesticide root zone model (PRZM) and the groundwater loading effects of agricultural management systems (GLEAMS). This literature information indicates that these models generally predict the same or greater leaching than observed in actual field measurements, suggesting that these models are suitable for use in regulatory assessments. However, additional validation research conducted using the newest versions of the models would help improve confidence in runoff and leaching predictions because significant revisions have been made in models over the years, few of the literature studies focused on runoff losses, the number of studies having quantitative validation results is minimal, and modelers were aware of the field results in most of the literature studies. Areas for special consideration in conducting model validation research include improving the process for selecting input parameters, developing recommendations for performing calibration simulations, devising appropriate procedures for keeping results of field studies from modelers performing simulations to validate model predictions while providing access for calibration simulations, and developing quantitative statistical procedures for comparing model predictions with experimental results. [source] Test substance characterization for the EPA: what you've always wanted to know but were afraid to ask,QUALITY ASSURANCE JOURNAL, Issue 3-4 2007William Barta Abstract The Society of Quality Assurance (SQA) GLP Specialty Section, a member of the SQA Regulatory Forum, is a group of participants from the regulated community which provides insight and guidance to our membership and the regulated community. The Specialty Section has encountered several participants who want to know what types of information and data are needed during an inspection by the US EPA's Office of Enforcement and Compliance Assurance (OECA). The OECA is responsible for monitoring studies submitted to the Office of Pesticide Programs in support of pesticide registrations as defined under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). All submitted studies are to be conducted according to the FIFRA US Good Laboratory Practice Standards (GLPS). The GLPS contain specific language concerning the characterization of test, control and reference substances used in these studies. This article clarifies those requirements and provides perspective on the EPA expectations on meeting those requirements. The topics of discussion include: regulatory requirements responsibilities of the testing facility management, study director, Quality Assurance Unit and the sponsor preparing for an inspection overview of data to be made available at the time of inspection composition of a Certificate of Analysis. Copyright © 2008 John Wiley & Sons, Ltd. [source] Nature of Resistance to Methyl Benzimidazole Carbamate Fungicides in Fusarium oxysporum f.sp. lilii and F. oxysporum f.sp. gladioli in TaiwanJOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2009Wen Hsin Chung Abstract Fusarium oxysporum f.sp. gladioli and F. oxysporum f.sp. lilii cause corm rot and yellowing of gladiolus and lilies respectively. Resistance among isolates of these two pathogens to two benzimidazole (methyl benzimidazole carbamate: MBC) fungicides, benomyl and thiabendazole, has been identified. However, sensitivity to other benzimidazole fungicides among isolates of F. oxysporum f.sp. gladioli and F. oxysporum f.sp. lilii remains unclear. Sensitivity among isolates of these two pathogens to benomyl, thiophanate-methyl, carbendazim and thiabendazole were evaluated in this study. Results showed that among six F. oxysporum f.sp. gladioli isolates, one was highly resistant, four were moderately resistant and one was highly sensitive to benomyl, five were highly resistant to thiophanate-methyl, four were sensitive and one was highly sensitive to carbendazim and all six isolates were sensitive to thiabendazole. Among the 13 F. oxysporum f.sp. lilii isolates tested, three were moderately resistant and 10 were highly sensitive to benomyl, and five were highly resistant, three were moderately resistant and five were sensitive to thiophanate-methyl. While all isolates were highly sensitive or sensitive to carbendazim and thiabendazole. These results strongly suggest that the mode of fungicide resistance in these two pathogens varies among members of the benzimidazole fungicide group and that cross resistance does not always occur. Sequence analysis of the partially amplified , -tubulin gene indicated that mutation in codons 198 and 200 had not occurred in the benzimidazole resistant isolates. It was concluded that resistance found in Taiwan isolates of F. oxysporum f.sp. gladioli and F. oxysporum f.sp. lilii to these fungicides may be due to some other mechanism. [source] Variation of Fungicide Resistance in Czech Populations of Pseudoperonospora cubensisJOURNAL OF PHYTOPATHOLOGY, Issue 3 2007J. Urban Abstract During the growing seasons between the years 2001 and 2004, 98 isolates of Pseudoperonospora cubensis from nine regions of Czech Republic were collected and screened for tolerance/resistance to the three frequently used fungicides (propamocarb, fosetyl-Al, metalaxyl). Fungicides were tested in five different concentrations, using a floating disc bioassay. Fungicide effectiveness varied considerably. Propamocarb appeared most effective and all the isolates collected in the years 2001,2003 were found sensitive to all tested concentrations [607,9712 ,g active ingredient (a.i.)/ml]. In 2004, some strains with increased resistance to propamocarb were detected. These strains were characterized by tolerance at the lowest concentrations (607 ,g a.i./ml, eventually on 1214 ,g a.i./ml); however, they were controlled by 2428 ,g a.i./ml. Fosetyl-Al was effective at the recommended concentration of 1600 ,g a.i./ml against all isolates. However, the occurrence of isolates (collected in 2001) which sporulated at low concentrations (400 and 800 ,g a.i./ml) indicated that the selection for tolerance occurs in the pathogen population. Nevertheless, this phenomenon was not confirmed with the P. cubensis isolates collected between the years 2002 and 2004. Metalaxyl was found ineffective, because 97% of the isolates showed the resistance to the recommended concentration (200 ,g a.i./ml), and the other 3% of isolates expressed tolerant response. The majority of the isolates showed profuse and/or limited sporulation at higher concentrations (400 and 800 ,g a.i./ml). A substantial shift to highly metalaxyl resistant strains was evident in the Czech P. cubensis populations during 2001,2004. [source] Protective, Curative and Eradicant Activity of the Strobilurin Fungicide Azoxystrobin against Cercospora beticola and Erysiphe betaeJOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2003T. Anesiadis Abstract The protective, curative and eradicant activity of the strobilurin fungicide azoxystrobin against Cercospora beticola and Erysiphe betae on sugar beet was determined under growth chamber conditions. Difenoconazole and chlorothalonil were used as standard fungicides against C. beticola, while chlorothalonil was replaced by sulphur against E. betae. Fungicides were applied before (protective treatments) and after (curative treatments) inoculation at 24, 48 and 96 h intervals, respectively. An additional spray treatment was applied after the appearance of the symptoms to evaluate the eradicant activity of the fungicides tested. Applications of azoxystrobin at 16 ,/ml provided 89,94% and 95,97% disease control against C. beticola and E. betae, respectively. Curative treatments of azoxystrobin either at 8 or 16 ,g/ml provided control of Cercospora leaf-spot higher than 90% only when it was applied 24 h after inoculation of the plants. Comparatively, chlorothalonil (100 ,g/ml) provided satisfactory control of C. beticola when applied in protective treatments (83,87% disease control) but showed little activity when applied after the inoculation of the seedlings (45,76% disease control). High control efficacy against E. betae was also obtained by protective applications of sulphur (600 ,g/ml) but the fungicide failed to provide satisfactory disease control, particularly when applied for 48 or 96 h after inoculation of seedlings. Difenoconazole (8 ,g/ml) gave excellent protective and curative activity against both pathogens. Eradicative treatments with azoxystrobin provided high antisporulant activity of 94,96% and 85,93% against C. beticola and E. betae, respectively. Similarly, high antisporulant activity was also provided by difenoconazole, while postsymptom applications of chlorothalonil and sulphur provided significantly lower antisporulant activity against C. beticola and E. betae, respectively. Such results encourage the evaluation of azoxystrobin under field conditions to determine optimal treatment schedules and to select possibly partner fungicides for use in mixtures. [source] Activity of Azole Fungicides and ABC Transporter Modulators on Mycosphaerella graminicolaJOURNAL OF PHYTOPATHOLOGY, Issue 6 2002I. STERGIOPOULOS The antimicrobial activity of the azole fungicides cyproconazole and propiconazole as single active ingredients and in mixtures with the ATP-Binding Cassette (ABC) transporter modulators rhodamine 6G, quercetin, quinidine, and verapamil and the strobilurin kresoxim-methyl was assessed against the wheat pathogen Mycosphaerella graminicola. Interactions amongst these compounds were evaluated on germination and germ tube growth of pycnidiospores using the Colby and Wadley method. Water agar proved to be the best test medium since all pycnidiospores germinated within 24 h of incubation and apical germ tube growth dominated over bud formation by intermediate cells. Analysis with the Colby method revealed that interactions between the compounds in all mixtures tested on germination of pycnidiospores were additive. With regard to germ tube growth, mixtures of cyproconazole and verapamil or kresoxim-methyl displayed a synergistic interaction. Analysis of mixtures of cyproconazole and kresoxim-methyl with the Wadley method revealed that the interaction between the two compounds was purely additive. These results indicate that the Colby method overestimated the interaction between these two compounds in a mixture. [source] Fungicide activity through activation of a fungal signalling pathwayMOLECULAR MICROBIOLOGY, Issue 6 2004Kaihei Kojima Summary Fungicides generally inhibit enzymatic reactions involved in fungal cellular biosynthesis. Here we report, for the first time, an example of fungicidal effects through hyperactivation of a fungal signal transduction pathway. The OSC1 gene, encoding a MAP kinase (MAPK) related to yeast Hog1, was isolated from the fungal pathogen Colletotrichum lagenarium that causes cucumber anthracnose. The osc1 knockout mutants were sensitive to high osmotic stress and showed increased resistance to the fungicide fludioxonil, indicating that Osc1 is involved in responses to hyperosmotic stress and sensitivity to fludioxonil. The Osc1 MAPK is phosphorylated under high osmotic conditions, indicating activation of Osc1 by high osmotic stress. Importantly, fludioxonil treatment also activates phosphorylation of Osc1, suggesting that improper activation of Osc1 by fludioxonil has negative effects on fungal growth. In the presence of fludioxonil, the wild-type fungus was not able to infect the host plant because of a failure of appressorium-mediated penetration, whereas osc1 mutants successfully infected plants. Analysis using a OSC1- GFP fusion gene indicated that Osc1 is rapidly translocated to the nucleus in appressorial cells after the addition of fludioxonil, suggesting that fludioxonil impairs the function of infection structures by activation of Osc1. Furthermore, fludioxonil activates Hog1-type MAPKs in the plant pathogenic fungi Cochliobolus heterostrophus and Botrytis cinerea. These results strongly suggest that fludioxonil acts as a fungicide, in part, through activation of the MAPK cascade in fungal pathogens. [source] Mechanisms influencing the evolution of resistance to Qo inhibitor fungicides,,PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 9 2002Ulrich Gisi Abstract Fungicides inhibiting the mitochondrial respiration of plant pathogens by binding to the cytochrome bc1 enzyme complex (complex III) at the Qo site (Qo inhibitors, QoIs) were first introduced to the market in 1996. After a short time period, isolates resistant to QoIs were detected in field populations of a range of important plant pathogens including Blumeria graminis Speer f sp tritici, Sphaerotheca fuliginea (Schlecht ex Fr) Poll, Plasmopara viticola (Berk & MA Curtis ex de Bary) Berl & de Toni, Pseudoperonospora cubensis (Berk & MA Curtis) Rost, Mycosphaerella fijiensis Morelet and Venturia inaequalis (Cooke) Wint. In most cases, resistance was conferred by a point mutation in the mitochondrial cytochrome b (cyt b) gene leading to an amino-acid change from glycine to alanine at position 143 (G143A), although additional mutations and mechanisms have been claimed in a number of organisms. Transformation of sensitive protoplasts of M fijiensis with a DNA fragment of a resistant M fijiensis isolate containing the mutation yielded fully resistant transformants, demonstrating that the G143A substitution may be the most powerful transversion in the cyt b gene conferring resistance. The G143A substitution is claimed not to affect the activity of the enzyme, suggesting that resistant individuals may not suffer from a significant fitness penalty, as was demonstrated in B graminis f sp tritici. It is not known whether this observation applies also for other pathogen species expressing the G143A substitution. Since fungal cells contain a large number of mitochondria, early mitotic events in the evolution of resistance to QoIs have to be considered, such as mutation frequency (claimed to be higher in mitochondrial than nuclear DNA), intracellular proliferation of mitochondria in the heteroplasmatic cell stage, and cell to cell donation of mutated mitochondria. Since the cyt b gene is located in the mitochondrial genome, inheritance of resistance in filamentous fungi is expected to be non-Mendelian and, therefore, in most species uniparental. In the isogamous fungus B graminis f sp tritici, crosses of sensitive and resistant parents yielded cleistothecia containing either sensitive or resistant ascospores and the segregation pattern for resistance in the F1 progeny population was 1:1. In the anisogamous fungus V inaequalis, donation of resistance was maternal and the segregation ratio 1:0. In random mating populations, the sex ratio (mating type distribution) is generally assumed to be 1:1. Therefore, the overall proportion of sensitive and resistant individuals in unselected populations is expected to be 1:1. Evolution of resistance to QoIs will depend mainly on early mitotic events; the selection process for resistant mutants in populations exposed to QoI treatments may follow mechanisms similar to those described for resistance controlled by single nuclear genes in other fungicide classes. It will remain important to understand how the mitochondrial nature of QoI resistance and factors such as mutation, recombination, selection and migration might influence the evolution of QoI resistance in different plant pathogens. © 2002 Society of Chemical Industry [source] ChemInform Abstract: Design, Synthesis, and Evaluation of Unsymmetrical Difluoro-Boron Complexes with Imidazoline as Potential Fungicides.CHEMINFORM, Issue 23 2010Kewei Wang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: X-Ray Investigations of Sulfur-Containing Fungicides.CHEMINFORM, Issue 1 2002Part 4. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Photomutagenicity of thiabendazole, a postharvest fungicide, in bacterial assaysENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2003Mie Watanabe-Akanuma Abstract We investigated the photomutagenicity of thiabendazole (TBZ), a postharvest fungicide commonly used on imported citrus fruits. Using UVA light (320,400 nm), we irradiated bacterial cultures with or without TBZ in a 24-well multiplate. UVA-irradiation without TBZ was not mutagenic to the tester strains, nor was unirradiated TBZ. TBZ was strongly photomutagenic in Escherichia coli WP2uvrA and WP2uvrA/pKM101 strains, weakly photomutagenic in Salmonella typhimurium TA100 and TA98, and not photomutagenic in S. typhimurium TA1535 and TA1538. The photomutagenicity of TBZ was more evident in WP2uvrA/pKM101, which carries the trpE65 ochre mutation (TAA), than in TA100, which carries the hisG46 missense mutation (CCC). In E. coli WP3101,WP3106 and the corresponding pKM101-containing strains, photoactivated TBZ induced predominantly G:C,A:T transitions and A:T,T:A transversions. In the plasmid-containing strains only, TBZ induced a moderate number of A:T,G:C transitions and a few A:T,C:G and G:C,T:A transversions. The observation that UVA-irradiated TBZ mutated both G:C and A:T basepairs may explain why WP2uvrA/pKM101 was more sensitive to its mutagenicity than TA100. TBZ that was irradiated before it was added to the WP2uvrA/pKM101 cells was not photomutagenic, which suggests that the photomutagenic products of TBZ were unstable or rapidly reacted with other molecules before being incorporated into cells. Environ. Mol. Mutagen. 41:92,98, 2003. © 2003 Wiley-Liss, Inc. [source] Persistent inhibition of human natural killer cell function by ziram and pentachlorophenolENVIRONMENTAL TOXICOLOGY, Issue 4 2005Thyneice R. Taylor Abstract Ziram is a currently used agricultural fungicide. It is also used as an additive in the production of latex gloves. Because of these uses, there is a potential for human exposure to this compound. Pentachlorophenol (PCP) has been used as an insecticide, fungicide, disinfectant, and ingredient in antifouling paints. Currently, it is used as a wood preservative for power-line poles and fence posts. Measurable levels of PCP have been detected in human blood and urine. In previous studies we demonstrated that both these compounds could cause very significant inhibition of the tumor-killing function of human natural killer (NK) cells. NK lymphocytes play a central role in immune defense against viral infection and the formation of primary tumors. So interference with their function could increase the risk of tumor development. In the present study we examined the effects of exposure to ziram or PCP of brief duration (1 h) on the ability of NK cells to destroy tumor cells. NK cells were exposed to either ziram (5,0.5 ,M) or PCP (10,5 ,M) for 1 h followed by 0 h, 24 h, 48 h, or 6 days in compound-free media and then were tested for the ability to lyse as well as to bind tumor cells. A 1-h exposure to as little as 2.5 ,M ziram decreased the ability of NK cells to lyse target tumor cells, which persisted up to 6 days following exposure. The loss of lytic function for from 24 h to 6 days following exposure was accompanied by a comparable loss of NK capacity to bind tumor cells. Exposure to 10 ,M PCP for 1 h caused a progressive loss (greater than 80%) of lytic function within 6 days of exposure. In contrast to ziram, PCP exposure caused no accompanying loss of binding function. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 418,424, 2005. [source] Effect of fungicides, endophytes and fungal filtrates on in vitro growth of Spanish isolates of Gremmeniella abietinaFOREST PATHOLOGY, Issue 4 2007O. Santamaría Summary The effect of eight fungicides and 15 endophytes isolated from twigs of healthy Pinus halepensis trees on the growth rate of four Spanish isolates of the pathogen Gremmeniella abietina was evaluated in vitro. In the fungicide experiments, four doses of each fungicide tested were added to the growth medium. In the endophyte experiments, dual cultures endophyte-pathogen were paired in Petri dishes. Furthermore, growth of three G. abietina isolates was evaluated on malt agar with pine needle extract amended with filtrates from cultures of endophyte E14, which produced a brownish compound apparently inhibiting G. abietina growth. The results obtained suggested that chlorothalonil and daconil were the most suitable fungicides at low doses to reduce growth of G. abietina isolates from Spain. Four of the endophytes tested in vitro showed strong antagonistic activity against G. abietina and deserve further testing in vivo. The endophyte E14 produced in vitro a brownish compound which almost completely inhibited mycelial growth of G. abietina isolates from Spain. [source] Effect of drought on the growth of Lolium perenne genotypes with and without fungal endophytesFUNCTIONAL ECOLOGY, Issue 6 2000G. P. Cheplick Abstract 1Grass leaves are often inhabited by fungal endophytes that can enhance host growth. In some forage species, endophytes improve host resistance to, and recovery from, drought. 2Our objective was to determine if the growth of genotypes of Lolium perenne L. was improved by endophytes during recovery from drought. 3Thirteen infected genotypes were cloned into ramets. Half were treated with a systemic fungicide to eliminate the endophyte (E,); half were untreated and retained high endophyte levels (E+). In a glasshouse, half of all E, and E+ ramets were watered regularly, whilst half were exposed to a 2 week drought on two occasions, each followed by a 3 week recovery period. 4After the first drought and recovery period, endophytes significantly reduced tiller production in the drought-stressed group. 5After the second drought and recovery period, effects of drought on live leaf area and dry mass were highly dependent on host genotype, but not endophytes. The mean tiller mass of E+ ramets after drought was significantly less than that of watered E+ ramets, but this was not true in E, ramets. For six genotypes there was greater mass allocation to storage in the tiller bases of E, ramets after drought. 6This perennial ryegrass population showed marked genotypic variation in the ability to recover from drought stress, but endophytes played little or no role in this ability. For some host genotypes there may be a metabolic cost of harbouring endophytes during environmentally stressful conditions. [source] Plant growth promotion and biological control of Pythium aphanidermatum, a pathogen of cucumber, by endophytic actinomycetesJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2009K.A. El-Tarabily Abstract Aims:, To evaluate the potential of Actinoplanes campanulatus, Micromonospora chalcea and Streptomyces spiralis endophytic in cucumber roots, to promote plant growth and to protect seedlings and mature plants of cucumber from diseases caused by Pythium aphanidermatum, under greenhouse conditions. Methods and Results:, Three endophytic isolates, out of 29, were selected through tests aimed at understanding their mechanisms of action as biocontrol agents and plant growth promoters. When applied individually or in combination, they significantly promoted plant growth and reduced damping-off and crown and root rot of cucumber. The combination of the three isolates resulted in significantly better suppression of diseases and plant growth promotion, than where the plants were exposed to individual strains. Conclusions:, The three selected actinomycete isolates colonized cucumber roots endophytically for 8 weeks, promoted plant growth and suppressed pathogenic activities of P. aphanidermatum on seedling and mature cucumber plants. Significance and Impact of the Study:, The results clearly show that the endophytic, glucanase-producing actinomycetes used, especially as a combined treatment, could replace metalaxyl, which is the currently recommended fungicide for Pythium diseases in the United Arab Emirates. These endophytic isolates also have the potential to perform as plant growth promoters, which is a useful attribute for crop production in nutrient impoverished soils. [source] The use of powder and essential oil of Cymbopogon citratus against mould deterioration and aflatoxin contamination of ,egusi' melon seedsJOURNAL OF BASIC MICROBIOLOGY, Issue 1 2005S. A. Bankole Dr. Experiments were carried out to determine the potential of using the powder and essential oil from dried ground leaves of Cymbopogon citratus (lemon grass) to control storage deterioration and aflatoxin contamination of melon seeds. Four mould species: Aspergillus flavus, A. niger, A. tamarii and Penicillium citrinum were inoculated in the form of conidia suspension (approx. 106 conidia per ml) unto shelled melon seeds. The powdered dry leaves and essential oil from lemon grass were mixed with the inoculated seeds at levels ranging from 1,10 g/100 g seeds and 0.1 to 1.0 ml/100 g seeds respectively. The ground leaves significantly reduced the extent of deterioration in melon seeds inoculated with different fungi compared to the untreated inoculated seeds. The essential oil at 0.1 and 0.25 ml/100 g seeds and ground leaves at 10 g/100 g seeds significantly reduced deterioration and aflatoxin production in shelled melon seeds inoculated with toxigenic A. flavus. At higher dosages (0.5 and 1.0 ml/100 g seeds), the essential oil completely prevented aflatoxin production. After 6 months in farmers' stores, unshelled melon seeds treated with 0.5 ml/ 100 g seeds of essential oil and 10 g/100 g seeds of powdered leaves of C. citratus had significantly lower proportion of visibly diseased seeds and Aspergillus spp. infestation levels and significantly higher seed germination compared to the untreated seeds. The oil content, free fatty acid and peroxide values in seeds protected with essential oil after 6 months did not significantly differ from the values in seeds before storage. The efficacy of the essential oil in preserving the quality of melon seeds in stores was statistically at par with that of fungicide (iprodione) treatment. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Ecosystem properties determined by plant functional group identityJOURNAL OF ECOLOGY, Issue 2 2010Jennie R. McLaren Summary 1.,Ecosystem properties may be determined by the number of different species or groups of species in a community, the identity of those groups, and their relative abundance. The mass ratio theory predicts that the effect of species or groups of species on ecosystem properties will be dependent on their proportional abundance in a community. 2.,Single plant functional groups (graminoids, legumes, non-leguminous forbs) were removed from a natural grassland in northern Canada to examine the role of group identity in determining both ecosystem properties and biomass compensation by remaining species. Removals were conducted across two different environmental treatments (fertilization and fungicide) to examine the context dependency of functional group identity effects. 3.,The degree of biomass compensation in the first 4 years after removal was influenced by the identity of the functional group removed and also of those remaining. When graminoids were removed, none of the remaining functional groups compensated for the loss of biomass. Graminoids partially compensated for the removal of forbs or legumes, with the degree of compensation depending on environmental treatments. 4.,Light interception, soil moisture and soil nutrients were all influenced by functional group identity, with graminoids having a greater impact than expected based on their biomass contribution to the community. Legumes, in contrast, had very little effect on any of the ecosystem properties measured. 5.,For most ecosystem properties measured, the role of plant functional groups was not context dependent; functional groups had the same effect on ecosystem properties regardless of fertilization or fungicide treatments. 6.,Synthesis. We have shown that the effects of losing a functional group do not solely depend on the group's dominance. In this northern grassland, there are greater effects of losing graminoids than one would predict based on their biomass contributions to the community, and functional group identity plays a critical role in determining the effects of diversity loss. [source] Pesticide residues and vertical integration in Florida strawberries and tomatoesAGRIBUSINESS : AN INTERNATIONAL JOURNAL, Issue 2 2001Richard L. Kilmer Government regulations and consumer concern about pesticide residues in food may increase the costs of production and marketing for producers and processors associated with food safety risks. Vertical coordination is an economic response for mitigating the costs associated with uncertain pesticide residue levels. Data from a survey of Florida strawberry and tomato growers were used to test the hypothesis that vertical integration is associated with a lower mean and variance of pesticide residues. The results confirm a significant negative relationship between vertical integration and fungicide and insecticide residues in Florida strawberries and insecticides in Florida tomatoes. However, fungicides in tomatoes had the opposite effect. [Econ-Lit citations: L220, L660] © 2001 John Wiley & Sons, Inc. [source] Searching for anthropogenic contaminants in human breast adipose tissues using gas chromatography-time-of-flight mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2009Félix Hernández Abstract The potential of gas chromatography-time-of-flight mass spectrometry (GC-TOF MS) for screening anthropogenic organic contaminants in human breast adipose tissues has been investigated. Initially a target screening was performed for a list of 125 compounds which included persistent halogen pollutants [organochlorine (OC) pesticides, polychlorinated biphenylss (PCBs), polybrominated diphenyl ethers (PBDEs)], polyaromatic hydrocarbons (PAHs), alkylphenols, and a notable number of pesticides from the different fungicide, herbicide and insecticide families. Searching for target pollutants was done by evaluating the presence of up to five representative ions for every analyte, all measured at accurate mass (20-mDa mass window). The experimental ion abundance ratios were then compared to those of reference standards for confirmation. Sample treatment consisted of an extraction with hexane and subsequent normal-phase (NP) High performance liquid chromatography (HPLC) or SPE cleanup. The fat-free LC fractions were then investigated by GC-TOF MS. Full-spectral acquisition and accurate mass data generated by GC-TOF MS also allowed the investigation of nontarget compounds using appropriate processing software to manage MS data. Identification was initially based on library fit using commercial nominal mass libraries. This was followed by comparing the experimental accurate masses of the most relevant ions with the theoretical exact masses with calculations made using the elemental composition calculator included in the software. The application of both target and nontarget approaches to around 40 real samples allowed the detection and confirmation of several target pollutants including p,p,-DDE, hexachlorobenzene (HCB), and some polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Several nontarget compounds that could be considered anthropogenic pollutants were also detected. These included 3,5-di- tert -butyl-4-hydroxy-toluene (BHT) and its metabolite 3,5-di- tert -butyl-4-hydroxybenzaldehyde (BHT-CHO), dibenzylamine, N -butyl benzenesulfonamide (N -BBSA), some naphthalene-related compounds and several PCBs isomers not included in the target list. As some of the compounds detected are xenoestrogens, the methodology developed in this paper could be useful in human breast cancer research. Copyright © 2008 John Wiley & Sons, Ltd. [source] High-performance liquid chromatographic/tandem mass spectrometric identification of the phototransformation products of tebuconazole on titanium dioxideJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 6 2002Paola Calza Abstract Tebuconazole is a widely used fungicide. The formation of by-products on irradiated titanium dioxide as a photocatalyst was evaluated. Several species derived from tebuconazole degradation were identified and characterized by HPLC/MSn. A pattern of reactions accounting for the observed intermediates is proposed. Different parallel pathways are operating (and through these pathways the transformation of the molecule proceeds), leading to a wide range of intermediate compounds. All these molecules are more hydrophylic than tebuconazole. The main steps involved are (1) the hydroxylation of the molecule with the formation of three species having [M + H]+ 324; the hydroxylation occurs on the C-1 carbon and on the aromatic ring in the two ortho -positions; (2) the cleavage of a C,C bond with the release of the tert -butyl moiety and the formation of a species having m/z 250; analogously to step 1, also on this species a further hydroxylation reaction occurs; (3) through the loss of the triazole moiety with the formation of a structure with m/z 257. Copyright © 2002 John Wiley & Sons, Ltd. [source] A Quantitative Polymerase Chain Reaction Assay for the Detection of Polyscytalum pustulans, the Cause of Skin Spot Disease of PotatoJOURNAL OF PHYTOPATHOLOGY, Issue 3 2009A. K. Lees Abstract Skin spot disease of potato caused by the pathogen Polyscytalum pustulans is likely to become more important with the withdrawal of 2-aminobutane as a fungicide, and new methods of control will need to be found. As part of a disease control strategy, it will be necessary to study the disease in more detail, to utilize host resistance and to identify stocks where problems are likely to arise. Existing methods for the detection and quantification of P. pustulans are time-consuming and require specific expertise. Real-time PCR assays have been developed for many pathogens of potato and have subsequently been used as tools for the study of the epidemiology and control of disease. The development of a real-time PCR assay for the detection and quantification of P. pustulans is described. The specificity of the assay was demonstrated and detection was shown to be reliable at levels as low as 20,250 fg/,l DNA, (equivalent to 60,680 pg DNA/g) in soil and on symptomless tubers at attogram (ag) levels. These values are in line with previously developed tests. [source] Analysis of Mycelial Growth Rates and RAPD-PCR Profiles in a Population of Gaeumannomyces graminis var. tritici Originating from Wheat Plants Grown from Fungicide-treated SeedJOURNAL OF PHYTOPATHOLOGY, Issue 6 2005Z. Weber Abstract Linear mycelial growth rates of 70 isolates of Gaeumannomyces graminis var. tritici on agar medium amended or unamended with the fungicide silthiofam were not correlated. Mycelial growth rate was not influenced by the fungicide applied to the seed of the plants from, which the isolates originated. DNA polymorphism determined by randomly amplified polymorphic DNA (RAPD) polymerase chain reaction was used to assess genetic variation among isolates. Thirty RAPD markers generated with five arbitrary 10-mer primers revealed DNA polymorphism suitable for assessing variability in this fungal population. Cluster analysis of RAPD data identified two groups at the 54% similarity level. There was a significant relationship between the presence of 11 markers and sensitivity to silthiofam. [source] Identification of Critical Stage for Disease Development and Biocontrol of Alternaria Blight of Indian Mustard (Brassica juncea)JOURNAL OF PHYTOPATHOLOGY, Issue 4 2004P. D. Meena Abstract Fungicides mancozeb and carbendazim caused 100% reduction in mycelial growth of Alternaria brassicae over control in vitro while 1% (w/v) aqueous bulb extract of Allium sativum and leaf extract of Acacia nilotica caused significant reductions. In dual culture, GR isolate of Trichoderma viride performed the best among the test isolates of Trichoderma, causing 81%, 82% reduction in mycelial growth of A. brassicae over control. Performance of isolates SI-2, P and SI-1 of T. viride were at par (P < 0.01) with that of GR isolate. Spraying of A. brassicae at different ages of the mustard host plant identified 75 days after sowing (d.a.s.) as the most critical age of the mustard plant for development of Alternaria blight severity on the crop with 45 d.a.s. being the next most important one. Mancozeb was the best among all the treatments, resulting in the lowest disease severity on leaves of mustard at both Sewar and Ludhavai as also the lowest A-value (area under disease progress curve). Performance of bulb extract of A. sativum in checking the disease severity on leaves and pods was at par (P,<,0.05) with mancozeb. The GR isolate of T. viride was at par with mancozeb in checking blight severity on mustard leaves at Sewar while performance of the bioagent was significantly (P,<,0.05) inferior to the chemical fungicide at Ludhavai. Performance of the bioagent isolate GR of T. viride in checking the disease severity on pods was at par (P < 0.05) with mancozeb at both Sewar and Ludhavai, the treatment recording the lowest A-value on pods. While application of bulb extract of A. sativum resulted in highest seed yield at Sewar in 2001,2002, the bioagent isolate GR of T. viride did so at Ludhavai, both the treatments being at par (P < 0.05) with mancozeb and significantly higher than control. Application of bulb extract of A. sativum at 45 and 75 d.a.s. resulted in lowest blight severity on leaves and pods as also in highest seed yield among the different single and combination of treatments. Although disease severity in the treatment was at par (P < 0.05) with that in mancozeb, application of the plant extract at the two stages of crop growth resulted in significantly higher seed yield compared with the two applications of the chemical fungicide. However, application of the treatments singly only at 75 d.a.s., GR isolate of T. viride at 45 and 75 d.a.s., A. sativum 45 d.a.s. + T. viride 75 d.a.s., and T. viride 45 d.a.s. + A. sativum 75 d.a.s. resulted in seed yield at par (P < 0.05) with application of bulb extract of A. sativum at 45 and 75 d.a.s. [source] Protective, Curative and Eradicant Activity of the Strobilurin Fungicide Azoxystrobin against Cercospora beticola and Erysiphe betaeJOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2003T. Anesiadis Abstract The protective, curative and eradicant activity of the strobilurin fungicide azoxystrobin against Cercospora beticola and Erysiphe betae on sugar beet was determined under growth chamber conditions. Difenoconazole and chlorothalonil were used as standard fungicides against C. beticola, while chlorothalonil was replaced by sulphur against E. betae. Fungicides were applied before (protective treatments) and after (curative treatments) inoculation at 24, 48 and 96 h intervals, respectively. An additional spray treatment was applied after the appearance of the symptoms to evaluate the eradicant activity of the fungicides tested. Applications of azoxystrobin at 16 ,/ml provided 89,94% and 95,97% disease control against C. beticola and E. betae, respectively. Curative treatments of azoxystrobin either at 8 or 16 ,g/ml provided control of Cercospora leaf-spot higher than 90% only when it was applied 24 h after inoculation of the plants. Comparatively, chlorothalonil (100 ,g/ml) provided satisfactory control of C. beticola when applied in protective treatments (83,87% disease control) but showed little activity when applied after the inoculation of the seedlings (45,76% disease control). High control efficacy against E. betae was also obtained by protective applications of sulphur (600 ,g/ml) but the fungicide failed to provide satisfactory disease control, particularly when applied for 48 or 96 h after inoculation of seedlings. Difenoconazole (8 ,g/ml) gave excellent protective and curative activity against both pathogens. Eradicative treatments with azoxystrobin provided high antisporulant activity of 94,96% and 85,93% against C. beticola and E. betae, respectively. Similarly, high antisporulant activity was also provided by difenoconazole, while postsymptom applications of chlorothalonil and sulphur provided significantly lower antisporulant activity against C. beticola and E. betae, respectively. Such results encourage the evaluation of azoxystrobin under field conditions to determine optimal treatment schedules and to select possibly partner fungicides for use in mixtures. [source] Leaf Disc Inoculation, a Fast and Precise Test for the Screening of Metalaxyl Tolerance in Sunflower Downy MildewJOURNAL OF PHYTOPATHOLOGY, Issue 6 2001B. Rozynek A new method, based on leaf disc inoculation, was developed for the screening of metalaxyl tolerance in field isolates of Plasmopara halstedii. High-pressure liquid chromatography (HPLC) was used to determine the fungicide concentration in the inoculation medium and in the incubated leaf tissue over the test period. These measurements revealed that the fungicide concentration inside the leaf tissue within 24 h had adjusted to the concentration in the outer medium and remained constant for the time of cultivation over a period of more than 11 days. In contrast to whole seedling tests with application of the fungicide via seed dressing, the leaf disc method allows precise quantification of the effective fungicide concentration at the site of infection and is less space and time consuming. Metalaxyl tolerance of P. halstedii isolates was gradually determined according to the sporulation of the pathogen on sunflower leaf discs in the presence of increasing fungicide concentrations. Isolates collected in South Germany showed no tolerance and sporulation was prohibited when tests were carried out at 0.02 ,g (a.i.)/ml of metalaxyl or more. In contrast, a tolerant French isolate developed sporangia on leaf discs incubated in a metalaxyl solution of 100 ,g (a.i.)/ml. [source] Fungicide activity through activation of a fungal signalling pathwayMOLECULAR MICROBIOLOGY, Issue 6 2004Kaihei Kojima Summary Fungicides generally inhibit enzymatic reactions involved in fungal cellular biosynthesis. Here we report, for the first time, an example of fungicidal effects through hyperactivation of a fungal signal transduction pathway. The OSC1 gene, encoding a MAP kinase (MAPK) related to yeast Hog1, was isolated from the fungal pathogen Colletotrichum lagenarium that causes cucumber anthracnose. The osc1 knockout mutants were sensitive to high osmotic stress and showed increased resistance to the fungicide fludioxonil, indicating that Osc1 is involved in responses to hyperosmotic stress and sensitivity to fludioxonil. The Osc1 MAPK is phosphorylated under high osmotic conditions, indicating activation of Osc1 by high osmotic stress. Importantly, fludioxonil treatment also activates phosphorylation of Osc1, suggesting that improper activation of Osc1 by fludioxonil has negative effects on fungal growth. In the presence of fludioxonil, the wild-type fungus was not able to infect the host plant because of a failure of appressorium-mediated penetration, whereas osc1 mutants successfully infected plants. Analysis using a OSC1- GFP fusion gene indicated that Osc1 is rapidly translocated to the nucleus in appressorial cells after the addition of fludioxonil, suggesting that fludioxonil impairs the function of infection structures by activation of Osc1. Furthermore, fludioxonil activates Hog1-type MAPKs in the plant pathogenic fungi Cochliobolus heterostrophus and Botrytis cinerea. These results strongly suggest that fludioxonil acts as a fungicide, in part, through activation of the MAPK cascade in fungal pathogens. [source] Allelochemical tricin in rice hull and its aurone isomer against rice seedling rot diseasePEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 9 2010Chui-Hua Kong Abstract BACKGROUND: One promising area of rice disease management is the potential of exploiting biological control agents. Rice seedling rot disease caused by soil-borne pathogenic fungi has become a dominant disease problem because of greater use of direct seeding. Rice hull has been potentially used to control paddy weeds, but little information is available on rice disease. This study was conducted to investigate the relationships between disease incidence and soil amended with tricin-releasing rice hull, and to assess fungicidal activity of tricin and its synthesised aurone isomer, with an attempt to develop an allelochemical-based fungicide against rice seedling rot disease. RESULTS: Tricin was detected in all hulls of 12 rice cultivars tested, but its contents in rice hulls varied greatly with the cultivar and genotype. Tricin in rice hulls was released into the soil once amended. Disease incidence was significantly reduced by soil amended with rice hull. Tricin-rich rice hull amendment greatly suppressed soil-borne pathogenic fungi Fusarium oxysporum Schlecht. and Rhizoctonia solani Kühn which cause rice seedling rot disease. In attempting to obtain enough tricin for further experiments, the aurone isomer (5,7,4,-trihydroxy-3,,5,-dimethoxyaurone) of tricin rather than tricin itself was unexpectedly synthesised. This aurone isomer had much stronger fungicidal activity on both F. oxysporum and R. solani than tricin itself. CONCLUSION: Soil amended with tricin-rich rice hull was associated with reduced risk of developing seedling rot disease. The tricin isomer, aurone, is more effective against rice seedling rot disease than tricin itself, making it an ideal lead compound for new fungicide discovery. Copyright © 2010 Society of Chemical Industry [source] In vitro effects of flutriafol and azoxystrobin on Beauvaria bassiana and its efficacy against Tetranychus urticaePEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 7 2010Mutimura C Gatarayiha Abstract BACKGROUND: Testing the compatibility of chemical pesticides and fungal biocontrol agents is necessary if these two agents are to be applied together in the integrated management of plant pests and diseases. In this study, the fungicides azoxystrobin (a strobilurin) and flutriafol (a triazole) were tested in vitro for their effects on germination of conidia and mycelial growth of Beauveria bassiana (Bals.) Vuill. and in bioassay for their effect on fungal activity against Tetranychus urticae Koch. The fungicides were tested at three different concentrations [recommended rate for field use (1 × X) and the dilutions 10,1× X and 10,2× X]. RESULTS: Flutriafol inhibited growth of mycelia and germination of the fungal conidia at all concentrations tested in vitro, and also reduced the efficacy of B. bassiana in bioassays against mites. The inhibitive effect of azoxystrobin in vitro varied with the concentration applied. A significant effect was observed at 1 × X and 10,1× X concentrations on both the germination of conidia and mycelia growth. At 10,2× X concentration, azoxystrobin showed little effect on B. bassiana. However, when this fungicide was tested in bioassays, none of the concentrations reduced B. bassiana activity against mites. CONCLUSION: Azoxystrobin was most compatible with B. bassiana, while flutriafol was the most harmful. Further studies are required to confirm the negative effect of flutriafol on B. bassiana activity. Copyright © 2010 Society of Chemical Industry [source] Inhibitory effect of bionic fungicide 2-allylphenol on Botrytis cinerea (Pers. ex Fr.) in vitro,PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 12 2009Shuangjun Gong Abstract BACKGROUND: 2-Allylphenol is a registered fungicide in China to control fungal diseases on tomato, strawberry and apple. It is synthetic and structurally resembles the active ingredient ginkgol isolated from Ginkgo biloba L. bark. 2-Allylphenol has been used in China for 10 years. However, its biochemical mode of action remains unclear. An in vitro study was conducted on the biochemical mechanism of 2-allyphenol inhibiting Botrytis cinerea (Pers. ex Fr.). RESULTS: The inhibition was approximately 3 times stronger when the fungus was grown on non-fermentable source, glycerol, than that on a fermentable carbon source, glucose. Inhibition of B. cinerea and Magnaporthe oryzae (Hebert) Barr mycelial growth was markedly potentiated in the presence of salicylhydroxamic acid (SHAM), an inhibitor of mitochondrial alternative oxidase. Furthermore, at 3 h after treatment with 2-allylphenol, oxygen consumption had recovered, but respiration was resistant to potassium cyanide and sensitive to SHAM, indicating that 2-allylphenol had the ability to induce cyanide-resistant respiration. The mycelium inhibited in the presence of 2-allylphenol grew vigorously after being transferred to a fungicide-free medium, indicating that 2-allylphenol is a fungistatic compound. Adenine nucleotide assay showed that 2-allylphenol depleted ATP content and decreased the energy charge values, which confirmed that 2-allylphenol is involved in the impairment of the ATP energy generation system. CONCLUSION: These results suggested that 2-allylphenol induces cyanide-resistant respiration and causes ATP decrease, and inhibits respiration by an unidentified mechanism. Copyright © 2009 Society of Chemical Industry [source] | |||||||||||||||||||||||||||||||||||||