Toxicity of 26 Fungicides against and Synergistic Effects of Binary Mixtures on Oidium heveae

[Objective] This study was conducted to determine the toxicity of 26 fungicides against Oidium heveae and the synergistic effects of their binary mixtures.[Method] The sensitivity of O.heveae to 26 fungicides was determined in vitro and in vivo by calculating EC50 values.Horsfall＇s toxicity rate was preliminarily employed to predict the type of joint action of 180 two-way mixtures,based on which the interaction level of the potentially synergistic mixtures was validated by Sun and Johnson＇s co-toxicity coefficient.[Result] Triflumizole,pyraoxystrobin,flufenoxystrobin,epoxiconazole,pyrametostrobin,flusilazole,pyraclostrobin and tetraconazole were the most potent inhibitors of both spore germination and mycelial growth.An ‘in vitro-in vivo＇ integrated strategy is proposed for screening the inhibitors of O.heveae,according to the fact that data obtained in germination experiment are able to reflect to some extent the effectiveness of fungicide confirmed by pot experiment.Results achieved by Horsfall＇s were in line with that validated by Sun and Johnson＇s,the Horsfall＇s seems to be a convenient means to assess rapidly the potential interaction type and level of fungicides in a binary mixture.Nineteen mixtures interact synergistically：epoxiconazole ＋ pyraclostrobin at the mixing ratio of 6：4,8：2;tetraconazole ＋ flufenoxystrobin at 1：9,2：8,3：7 and 4：6;triadimefon ＋ flufenoxystrobin at 9：1;triflumizole ＋ flufenoxystrobin at 8：2;flusilazole ＋pyrametostrobin at 7：3,8：2 and 9：1;tetraconazole ＋ pyrametostrobin at 6：4;triadimefon ＋ pyrametostrobin at 5：5,8：2;triflumizole ＋ pyrametostrobin at 7：3,8：2;tetraconazole ＋ pyraoxystrobin at 9：1;triflumizole ＋ pyraoxystrobin at 8：2,9：1.[Conclusion] The single fungicides and their binary mixtures are expected to serve as the alternatives to triadimefon and the alternate use of them could delay the buildup of resistant O.heveae isolate.

The Effect of Three New Fungicides against Rice Sheath Blight in Field Experiment

[Objective] The aim was to study the effect of three new fungicides against rice sheath blight in field experiment. [Methods] The experiment set up 7 treatments with three times of repetition and designed by random grouping. By using 5 sampling points in each plot, and investigating continuous 4 holes of each point, total plants, diseased plants and disease degrees were recorded. Then disease index and control efficiency were calculated, and variance analysis was carried out. [Results] 300 or 450 ml/hm^2 azoxystrobin ＋ difenoconazole 325 g/L SC had better control efficiency to rice sheath blight and had no phytotoxicity effect, we should use it at the initial disease stage and continuously spray 2-3 times. [Conclusion] The experiment provided a theoretical basis for controlling rice sheath blight using fungicides.

Biological Activity of Several Fungicides against Ustilaginoidea virens

[Objective] This study aims to screen for the high effective fungicides which could significantly decrease the disease incidence and disease index of rice false smut. [Method] The inhibitory activities of the fungicide against mycelial growth of Ustilaginoidea virens were measured to in vitro evaluate the ECho values. And 17 fungicides were sprayed to evaluate the efficacy and effect of the fungicides tested in the field trials on the rice characters, [Result] The results showed that epoxicona- zole, difenoconazole, propiconazole and procloraz exhibited high inhibitory activity against mycelial growth of Ustilaginoidea virens with the ECso values 0.04, 0.07, 0.12 and 0.11 pg/ml, respectively. The results of field trials showed that the efficacy of Wen- quning, and fungicides such as difenoconazole, prochloraz, propiconazole, epoxi- conazole and their mixtures in controlling rice false smut were all 70% or more. [Conclusion] The 17 tested fungicides behaved efficacy in controlling rice false smut and did not cause drug injury on leaves and grains of rice plants, sprayed when flag leaves of rice fully expanded.

Inhibitory Effect of 16 Fungicides on Persimmon Anthracnose Pathogen Colletotrichum horii

In this research,the inhibitory effect of 16 fungicides on Colletotrichum horri causing persimmon anthracnose was investigated using mycelial growth method and spore germination method. The results showed that among the 16 tested fungicides,10% of Difenoconazole WG,33. 5% of Copper quinolate SC,25%of Bromothalonil EC,70% of Mancozeb WP,430 g/L of Tebuconazole SC,50% of Prochloraz-manganese chloride and 400 g/L of Flusilazole EC achieved the best inhibitory effect on mycelial growth of C. horri,with the inhibition rate of 100%; 70% of Polyram WG,33. 5% of Copper quinolate SC,25% of Bromothalonil EC,70% of Mancozeb WP,50% of Chlorobromoisocyanuric acid AF,50% of Triram WP and 400 g/L of Flusilazole achieved the best inhibitory effect on spore germination of C. horri,with the germination rate of 0. In conclusion,33. 5% of Copper quinolate SC,25% of Bromothalonil EC,70% of Mancozeb WP and 400 g/L of Flusilazole EC achieved the best inhibitory effect both in mycelial growth and spore germination,which could be used as the preference fungicides for the control of persimmon anthracnose,and 70% of Polyram WG and 50% of Triram WP achieved the secondly best inhibitory effect,which could be used as alternative fungicides. The results of this research could provide scientific evidence for the effective control of persimmon anthracnose,and more optional pesticides for utilization in the production practice of persimmon industry.

Field Efficacy of Six Kinds of Fungicides for Control and Prevention of Apple Powdery Mildew(Podosphaera leucotricha)

[Objective] This study aimed to screen effective fungicide for prevention and control of apple powdery mildew. [Method] Field efficacy of six kinds of fungi- cides with 18 concentrations against apple powdery mildew was investigated. [Re- sult] 4 000-fold triflumizole WP exhibited the highest control efficacy of 82.96%, fol- lowed by 3 000-fold triflumizole WP with control efficacy of 77.75%, while 800-fold and 1 000-fold 70% thiophanate methyl WP exhibited relatively low control efficacy, which was both lower than 60%. [Conclusion] In actual production, 4 000-fold triflu- mizole WP and 3 000-fold triflumizole WP should be used alternately to control and prevent apple powdery mildew.

Inhibition of Chlamydospore Germination and Mycelial Growth of Trichoderma spp. by Chemical Fungicides

For exploring the influences of application and residue of chemical fungi- cides on chlamydospore preparations of Trichoderma spp., the effects of seven chemical fungicides on chlamydospore germination and mycelia growth of two bio- control fungi T. harzianum 610 and T. Iongibrachiatum 758 were studied. Carben- dazim, tebuconazole and difenoconazole showed strong toxicities, thiram and car- bexin showed moderate toxicities, and metalaxyl showed Mycelia growth of the two strains was more sensitive to most tested fungicides than those of chlamydospore germination. Chlamydospore germination of 610 was more sensitive to tested fungicides than those of 758, and mycelia growth of 758 was more sensitive to most tested fungi- cides than those of 610. Among the seven fungicides, 98% carbendazim had the strongest effects （ECru values were 1.64 and 0.05μpg/ml）, and 70% pentachloroni- trobenzene had the weakest effects （EC50 values were 1.64 and 0,05 μg/ml） for chlamydospore germination and mycelia growth of 610. As for 758, 98% carbendaz- im had the strongest inhibitory effects and 95% metalaxyl had the weakest inhibitory for chlamydospore germination of 756 （EC50 values were 0.62 and 1 108.61 μg/ml respectively）, whereas 96.2% tebuconazole showed the strongest inhibitory effects for mycelia growth of 758 （EC= value was 0.32μg/ml）, and 95% metalaxyl was the weakest （EC= value was 1 206.29 μg/ml）. According to the applied concentration of different fungicides in practice, we concluded that chlamydospore preparations of 610 and 758 could not be combined with carbendazim, tebuconazole, thiram and carboxin for controlling plant diseases, and the pesticide residues to the biocontrol effects should be kept in mind. Chlamydospore preparations of 610 and 758 can be and difenoconazole for controlling plant dis- eases, 758 chlamydospore preparations and germinated chlamydospore of 610 can be combined with metalaxyl for controlling plant diseases, and pesticide residue risk was not serious.

Antibiotic Activity of Seven Fungicides against Alternaria panax Whetz

[Objective] This study was conducted to screen suitable fungicides to con-trol ginseng leaf blight caused by Alternaria panax_Whetz. [Method] The antifungal activity of seven fungicides against A. panax_ was determined based on mycelial growth rate in vitro. [Result] The results of in vitro antibiotic activity assay showed that there were significant differences in inhibition rate among different concentration treatments of each of the seven fungicides. Toxicity test results showed that among the seven fungicides, difenoconazole had the smal est EC50 （0.61 mg/L）, fol owed by streptomycin and captan, with EC50 value lower than 100 mg/L. [Conclusion] A fungicide which had strong antifungal activity on A. panax was screened out, and the results wil provide a theoretical basis for further field trial.

Effect of <i>Trichoderma harzianum</i>in Combination with Fungicides in Controlling Gray Mould Disease (<i>Botrytis cinerea</i>) of Strawberry

The effects of biofungicide formula containing the biocontrol agent Trichoderma harzianum (Jn14) as wettable powder in combination with the fungicides pyrimethanil and a mixture of cyprodinil and flydioxonil on Botrytis cinerea of strawberry in vitro, in vivo and in greenhouse were studied. The pathogen B. cinerea was more affected in vitro by low concentrations of the fungicides tested above 0.4 μg&middot;ml-1 than the bioagent T. harzianum (Jn14). The later was almost insensitive to pyrimethanil. In the same direction, gray mould disease severity on strawberry detached leaves and whole plants was reduced up to 89% by the tested fungicides, compared to the control, while the application of T. harzianum (Jn14) alone reduced disease severity up to 45% on strawberry detached leaves, compared to the control. In the integrated control approach, the combination of T. harzianum (Jn14) with higher concentrations of the tested fungicides (ED50) completely inhibited strawberry gray mould disease severity in pots and the greenhouse.

Mitochondrial dynamics caused by QoIs and SDHIs fungicides depended on FgDnm1 in Fusarium graminearum

Fusarium head blight(FHB) caused by Fusarium graminearum is a devastating fungal disease on small grain cereal crops,because it reduces yield and quality and causes the mycotoxin contamination to the grain.Dynamins and dynamin-related proteins(DRPs) are large GTPase superfamily members,which are typically involved in the budding and division of vesicles in eukaryotic cells,but their roles in Fusarium spp.remain unexplored.Here,we found that FgDnm1,a DRP and homolog to Dnm1 in Saccharomyces cerevisiae,contributes to the normal fungal growth,sexual reproduction and sensitivity to fungicides.In addition,we found FgDnm1 co-localizes with mitochondria and is involved in toxisome formation and deoxynivalenol(DON) production.Several quinone outside inhibitors(QoIs) and succinate dehydrogenase inhibitors(SDHIs) cause fragmentated morphology of mitochondria.Importantly,the deletion of FgDnm1displays filamentous mitochondria and blocks the mitochondrial fragmentation induced by QoIs and SDHIs.Taken together,our studies uncover the effect of mitochondrial dynamics in fungal normal growth and how such events link to fungicides sensitivity and toxisome formation.Thus,we concluded that altered mitochondrial morphology induced by QoIs and SDHIs depends on FgDnm1.

Sensitivity of Four Yeasts to Fungicides and CO2 Concentrations and Their Antagonistic Ability in Combination with Fungicide to Pathogenic Fungi in vitro

The yeasts Cryptococcus laurentii, Trichosporon pullulans, Rhodotorula glutinis andTrichosporon sp.were used to investigate their sensitivity to four fungicides anddifferent concentrations of CO2, as well as their antagonistic ability to Penicilliumexpansumand Alternariaalternata in vitro when applied with fungicide. There were significantdifferences in sensitivity to the fungicides among the different yeasts(P=0.05). R.glutinis was more sensitive to Deccocil, Iprodione and Stroby as compared to otheryeasts. Combination antagonistic yeasts with fungicide could more significantly enhancebiocontrol ability of the yeasts against the pathogenic fungi in vitro(P = 0.05). C.laurentii was the most effective antagonist among the four yeasts and could completelycontrol spore germination of P.expansum and A.alternata when combined with Stroby at theconcentration of 100 L L-1. The yeasts, except R.glutinis, could grow well on nutrientyeast dextrose agar (NYDA) after 8 d incubation even at 20% CO2 concentration at 25℃.Particularly Trichosporon sp. showeda better adaptability to low temperature as comparedto other antagonists.

Phytochemical Analysis and Antifungal Activity of Extracts from Leaves and Fruit Residues of Brazilian Savanna Plants Aiming Its Use as Safe Fungicides

The increasing demand for safe food without preservatives or pesticides residues has encouraged several studies on natural products with antifungal activity and low toxicity.In this study,ethanolic extracts from leaves and fruit residues(peel and seeds)of three Brazilian savanna species(Acrocomia aculeata,Campomanesia adamantium and Caryocar brasiliense)were evaluated against phytopathogenic fungi.Additionally,the most active extract was chemically characterized by ESI-MS and its oral acute toxicity was evaluated.Extracts from C.brasiliense(pequi)peel and leaves were active against Alternaria alternata,Alternaria solani and Venturia pirina with minimal inhibitory concentrations between 350 and 1000 lg/mL.When incorporated in solid media,these extracts extended the lag phase of A.alternata and A.solani and reduced the growth rate of A.solani.Pequi peel extract showed better antifungal activity and their ESI-MS analysis revealed the presence of substances widely reported as antifungal such as gallic acid,quinic acid,ellagic acid,glucogalin and corilagin.The oral acute toxicity was relatively low,being considered safe for use as a potential natural fungicide.

Medicinal Plants, A promising Source of Natural Fungicides against <i>Magnaporthe oryzae Triticum</i>, Causal Agent of Wheat Blast

Wheat blast, caused by a fungal pathogen, Magnaporthe oryzae Tritichum (MoT) pathotype (wheat isolates), was first reported in Bangladesh among Asian countries in 2016. It is a serious disease of wheat causing yield failures and significant economic losses during epidemic years. Extensive use of persistent synthetic pesticides to control notorious wheat blast imposes enormous threat to human health and environment. In addition, the increasing demand for organic food has stimulated people to look for alternative methods. Nowadays, the need for synthetic chemical-free agricultural practices is gaining importance due to effective in managing crop pests, inexpensive, biodegradable, easily available and have low toxicity to non-target organisms. In order to identify active plants, 12 kinds of methanol extracts obtained from 12 medicinal plants were conducted in vitro to test the effect against Magnaporthe oryzae Triticum (MoT) pathotype. The remarkable inhibitory activity {(29.6 ± 01.5) mm, (25.1 ± 01.0) mm and (20.0 ± 02.0) mm zone of inhibition)} exhibited by the extracts (5 mg/disk) obtained from Artemisia indica (Nagdona), Persicaria orientalis (Bishkatali) and Clerodendrum indicum (Bamonhati), respectively. Other medicinal plant extracts did not show any significant or no activity at all. Therefore, the three plant extracts might be a promising source for developing natural fungicides against wheat blast.

Comparative Study of Bunt Pathogen Resistance to the Effects of Fungicides in Callus Co-Cultures <i>Triticum aestivum</i>with Tilletia caries

The morphophysiological and molecular-genetic parameters of T. caries isolates collected from various fields of Southern Urals agrocenoses have been analysed. Isolate 1 of wheat callus had a high growth rate in vitro even in the presence of 0.1 mg/l fungicide Baitan. Isolate 2 of wheat callus had a low growth rate whereas 0.1 mg/l Baitan significantly inhibited its growth. Comparison of nucleotide sequences of 18S RNA gene of the two isolates showed high level of homology between them, but a large number of nucleotide substitutions have been found. The most characteristic excision was five nucleotides at position 461 of the isolate 2, compared with the isolate 1. Our results allow to assume that the environmental stress including high pesticide concentration may cause the resistance of T. caries pathogen to fungicides.

Identification of Postharvest Pathogens of Amorphophallus muelleri and Indoor Screening of Fungicides

Konjac （Amorphophallus muelleri）, a genus of tuberous plants in the Araceae family, is one of high-value crops in Southwest China. This study aimed at identifying the main pathogens causing tuber rot during storage ofA. muelleri and screening the effective fungicides, so as to prolong the storage period ofA. muelleri and decrease the losses. Isolation and identification, as well as pathogenicity test and retro-inoculation experiments were made for the pathogen causing tuber rot during storage ofA. muelleri in Kunming city, Yunnan province, China. The effective fungicides for the main pathogens were also screened in the laboratory. Six fungi were identified as the pathogens causing tuber rot of A. muelleri, which were Fusarium solani （Mart,） Sacc., Fusarium oxysporum Schlecht., Botrytis cinerea Pers., Alternaria alternata （Fr.） Keissl., Rhizopus nigricans Ehrenb., Penicillium ulaiense Hsieh, Su ＆ Tzean. The main pathogens causing postharvest diseases ofA. muelleri were F. solani, F. oxysporum and B. cinerea. The isolation frequencies of them were 33.9%, 10.5% and 19.4%, respectively. After artificial inoculation, the incidence of tubers infected by F. solani, F. oxysporum and B. cinerea was 100%, 83% and 95%, respectively. The results of chemical screening showed that, in potato dextrose agar （PDA） media plate, the compounds Fludioxonil （50% WP） and Boscalid （50% WG） were the most effective in controlling the three main pathogens, and the average effect reached more than 97%. The test of fungicidal antisepsis on tubers consisted ofA. muelleri being dipped in the 9,000x diluted solution of Fludioxonil （50% WP） or in the 3,500x diluted solution of Boscalid （50% WG） for 3 min and stored at room temperature （25 ℃） for 7 d and 15 d, respectively. The fungicidal effects of Fludioxonil against F. solani, F. oxysporum and B. cinerea for 7 d and 15 d were 88.6%/83.2%, 90.1%/84.7% and 93.0%/91.5%, respectively, whereas the fungicidal effects of Boscalid were 87.0%/85.3%, 89.0%/85.6% and 89.2%/89.1%, respectively. The results may provide useful information for the control ofpostharvest diseases ofA. muelleri.

Pathogen Identification of the Anthracnose of Ligusticum chuanxiong Hort. and Inhibitory Effect of Four Fungicides on the Pathogen

[Objective] The research aimed to isolate and identify the pathogen of anthracnose of Ligusticum chuanxiong Hort,and make the antifungal test on four kinds of fungicides for selecting the optimum fungicides.[Method] The pathogenic fungi was separated according to Koch＇s rule and the shape characteristics were identified. The antifungal test of fungicides was made by using plate mycelium growth inhibition method.[Result] The pathogenic fungi was separated from leaves of Ligusticum chuanxiong Hort. and morphological characters were consistent with that of Colletotrichum gloeosporioides. In addition to chloroisobromine cyanuric acid,the other three fungicides could inhibit the mycelium growth. The growth inhibition rates of 1 000 times Metalaxyl＋mancozeb,zineb,Thiophanate-methyl for the mycelium were 26.8%,22.1%,59.8% respectively after 7 days.[Conclusion] The anthracnose was caused by Colletotrichum gloeosporioides. Ligusticum chuanxiong Hort. was a new record host plant of Colletotrichum gloeosporioides and the best inhibiting fungicide was Thiophanate methyl.

Determination of trace amounts of chlorinated insecticides and fungicides in ginseng using capillary gas chromatography and ^(63)Ni electron capture detector

A method for the simultaneous determination of a series of chlorinated insecticides and fungicides as residues in ginseng is presented in this article. Pulverized samples are subjected to Soxhlet extraction with acetone-petroleum ether and the extract is partitioned between petroleum ether and aqueous sodium sulfate solution (2:98). The combined petroleum ether phase is cleaned up by sulfuric acid and analyzed by capillary gas chromatography using 63Ni electron capture detector. Recoveries from the different concentrations for 11 kinds of chlorinated insecticides and fungicides are between 92.40 and 103.7% with coefficients of variations ranged 1.22 and 9.53% without samples, and between 89.00% and 104.10% with coefficients of variations between 1.16% and 9.16% with samples. The detection limits are 0.2- 7.0 ng/kg.

Synthesis of 5,7-Dimethyl-2-(5-Substituted-1,3,4-Oxadiazole-2-yl)- Methylenethio-1,2,4-Triazolo[1,5-a]Pyrimidines as Potential Fungicides

A series of diheterocyclic compounds containing 1,2,4-triazolo [1,5-a]pyrimidine and 1, 3,4-oxadiazole were designed and synthesized starting from 2-mercapto-5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine. The structure of all compounds prepared were confirmed by H-1 NMR spectroscopy and elemental analysis. The preliminary bioassay indicated that the title compounds displayed good fungicidal activity against Rhizoctonia solani.

Efficacy of Different Fungicides against Mango Anthracnose in Senegalese Soudanian Agroclimate

Anthracnose is the one of the most devastating diseases of mango produced in the southern part of Senegal. The field trials against post harvest rot due to anthracnose took place in three orchards over two production seasons, in 2009 and 2010. Three systemic fungicides (thiophanate methyl, azoxystrobin and myclobutanyl) and one contact fungicide (mancozeb) were tested for their efficacy. The first treatments in 2009 took place in the rainy season, while 20% of mangoes on trees exhibited anthracnose lesions. At ripening stage, 100% of fruits from non treated control mango trees were affected by anthracnose and got rotten, while between 73.2% and 80% of mangoes ripened free of disease when treated with thiophanate methyl. With the treatment with azoxystrobin, between 46.6% and 60% of fruits were not infected. Treatment with myclobutanyl was less effective. This level of effectiveness was clearly improved in 2010 by preventive spraying, days ahead of onset of the rainy season, before the appearance of anthracnose symptoms on fruits. The level of effectiveness was higher respectively for thiophanate methyl (between 96% and 100% of fruits not infected) and azoxystrobin (between 84% and 96% of fruits not infected).

Indoor Toxicity and Field Efficacy of Five Strobilurins Fungicides against Phomopsis asparagi (Sacc.) Bubak

[Objective]The study was to evaluate the indoor toxicity and field efficacy of five Strobilurins fungicides including pyraclostrobin 250 g/L EC,azoxystrobin 250 g/L SC,kresoxim-methyl 50%WG,picoxystrobin 22.5%SC and trifloxystrobin 50%WG against Phomopsis asparagi(Sacc.)Bubak,and to screen out effective fungicides.[Method]The toxicity was tested by mycelial growth rate method.The field trials were carried out by routine spraying method.[Result]The indoor toxicities successively were pyraclostrobin>kresoxim-methyl>picoxystrobin>trifloxystrobin>azoxystrobin.The EC50 values were 6.1029,52.5591,83.8257,129.8616 and 252.1214 mg/L,respectively,all significantly higher than that of benzimidazole fungicide carbendazim(753.3650 mg/L).The field efficacies successively were pyraclostrobin>kresoxim-methyl≥picoxystrobin≥azoxystrobin≥trifloxystrobin.The control effects were 81.20%,77.95%,74.80%,71.69%and 68.54%,respectively,all significantly higher than that of benzimidazole fungicide carbendazim(48.27%).[Conclusion]The five Strobilurins fungicides all have good toxicity and field efficacy against P.asparagi.

Influence of Fungicides on Almond Pollen Germination and Fruit Set

The almond （Prunus dulcis） is a self-incompatible species that requires various orchard management techniques to encourage pollination and achieve a good fruit set. Fungicides are commonly applied to almond flowers to control fungaI infections, such as ＂blossom blight＂ and ＇brown rot＂ that damage the flowers and developing fruits. However there is evidence that the application of some of these products may adversely affect pollination and fruit set. The effects of the fungicides captan, chlorothalonyl, propiconazole, mancozeb and dichloran on fruit set were studied in an orchard using ＂Nonpareil＂ and ＂Carmel＂ almond trees. The effects on in vitro pollen germination and pollen tube elongation were studied using ＂Carmel＂ pollen. With respect to Non Pareil fruit set, all fungicidal treatments were statistically similar to the control （11.5%） but being propiconazole （13.1%） and chlorotalonil （5.6%） different between them. Fruit set for ＂Carmel＂ was significantly lower than the control （26.1%） with all fungicidal treatments. After 24 hours, in vitro ＂Carmel＂ pollen germination was significantly higher in the control （90.5%） compared with the fungicidal treatments, with the exception of chlorothalonyl （70.2%）. Pollen tube growth in the control was four times greater than in the fungicide treatments at 24 hours, none of which were significantly different from the other treatments. It can be concluded that the application of certain fungicides has a clearly detrimental effect on fruit set in ＂Nonpareil＂ and ＂Carmel＂ almond trees and on ＂Carmel＂ pollen activity.