Efficacy of Fungicides and Optimization of Application Timing for the Management of Sclerotinia Rot of Mustard Caused by Sclerotinia sclerotiorum

Sclerotinia rot of rapeseed-mustard caused by Sclerotinia sclerotiorum (Lib.) de Bary has gained significant importance in Rajasthan, Punjab, Haryana and other major rapeseed-mustard growing areas of India in recent years. Fungicides are extensively used for the control of this disease since no commercial cultivars have been found resistant to S. sclerotiorum and other management practices have not been found very effective. Therefore, the present investigations were carried out to evaluate the efficacy of fungicides and to optimize application timing for the effective management of Sclerotinia rot of mustard. Among 08 fungicides tested in vitro, Carbendazim 50% WP and Propiconazole 25% EC were found most efficient at completely inhibiting the mycelial growth of S. sclerotiorum at all the concentrations tested. In an in vitro sclerotial (carpogenic) germination test, Carbendazim 50% WP completely inhibited sclerotial germination at 100, 250 and 500 ppm. Under artificial inoculation conditions in the field, Propiconazole 25% EC @0.1% was found most effective in reducing Sclerotinia rot incidence (87.04%) followed by Carbendazim 50% WP (83.33%) and Tebuconazole 25.9% EC (75.93%). Similarly, under natural epiphytotic conditions in field, Propiconazole 25% EC @0.1% was found best in disease incidence reduction (85.34%) with increased yield (40.00%) followed by Carbendazim 50% WP (81.25% & 38.09%) and Tebuconazole 25.9% EC (79.72% & 35.24%) in disease reduction and increased yield respectively. Differential time and frequency of application of Propiconazole @0.1% were tested and found that 02 applications i.e. 1st spray at 4.2 flowering stage i.e. 30% bloom stage (70 DAS) and 2nd spray at 4.3 flowering stage i.e. 50% bloom stage (85 DAS) was equally effective in disease incidence reduction (82.70%) with 03 applications i.e. 1st spray at 4.1 flowering stage i.e. 10-20% bloom stage (55 DAS), 2nd at 4.2 flowering stage (70 DAS) and 3rd at 4.3 flowering stage (85 DAS). Therefore, the optimization of fungicide application timing and the number of sprays with adequate concentrations is advisable to increase the cost-effectiveness of crop production while controlling the disease.

Efficacy of Fungicides and Commercially Available Organic Products against Blight of Cotton Caused by Alternaria macrospora

An attempt was made to test available formulation of fungicides and commercially available organic products for their efficacy under laboratory condition, an experiment was carried out at Department of Plant pathology, Raichur, Karnataka, India by using poison food technique. Among the commercially available organic products tested, fatty alcohol and diluents has recorded significantly higher mycelial inhibition of 100 per cent at the concentration of 5 and 10 per cent. In case of contact fungicides propineb 70% WP, metiram 70% WP and mancozeb 75 % WP recorded 100 per cent mycelial inhibition, with respect to systemic fungicides hexaconazole 5% EC, propiconazole 25% EC and difenoconazole 25% WP and among the combi fungicides azoxystrobin 8.3% + mancozeb 66.7% WG were most effective in 100 per cent inhibition of mycelial growth of Alternaria macrospora over the control. The commercially available organic product fatty alcohol and diluents, propineb 70% WP, hexaconazole 5% EC, propiconazole 25% EC and azoxystrobin 8.3% + mancozeb 66.7 % WG were found to be effective against inhibition of mycelial growth of Alternaria macrospora.

In vivo Bio-efficacy of Fungicides and Antagonists for the Management of Target Leaf Spot of Soybean [Corynespora cassiicola (Berk. and Curt.) Wei]

Foliar diseases cause major qualitative and quantitative yield loss in soybean, among which target leaf spot of soybean caused by Corynespora cassiicola is one of the constraints. Hence, management of this disease is much needed effort. Thus the present investigation was carried out for management of the disease under field condition using fungicides and bioagents that were effective in inhibiting the pathogen under in vitro studies. Among the different treatments evaluated, seed treatment with (pyraclostrobin 5% + thiophanate methyl 45%) @ 2 ml/kg seed followed by spray with (tebuconazole 50% + trifloxystrobin 25%) @ 0.05% at 55 and 75 days after sowing (DAS) recorded the least disease severity of 2.23 percent with higher seed yield (17.20 q/ha) and test weight (17.41 g) as compared to untreated check which recorded disease severity of 27.50 percent. Apart from the target disease, other diseases like rust, anthracnose and Alternaria leaf spot were also take care in the same treatment. Use of fungicides for the management of disease in the absence of resistant genotypes is an old practice and it is one of the best options when there is outbreak.

A Review on Sustainable Alternatives of Post Harvest Treatments in Fruits

The fruit farming industry faces spoilage and disease after harvest, with Colletotrichum being the most common cause. Safer, more effective, biorational, and sustainable disease management are suggested. Plant-based essential oils (Eos) have synergistic antimicrobial, herbicide, insecticide, antioxidant, and fungicide properties that can fight agricultural fungi. Due to their negative effects on agroecosystems and public health, the OECD recommends a switch to sustainable food systems and synthetic fungicides. Essential oils are complex lipids from plants' secondary metabolism that are allelopathic, herbivorous, and phytopathogenic microorganism-protective. Their effects on bacteria and fungi include cell wall degradation, cytoplasmic and lipid membrane synthesis interference, lysis, cell death, and mitochondrial dysfunction. Essential oils were shown to treat postharvest diseases in apple cultivars and Penicillium spp., B. cinerea in strawberries and apples. Combining essential oils and non-toxic additives can control fruit postharvest fungal infections. Immersion, spraying, fumigation, and volatilization can be applied to fruit. Researchers suggest adding essential oils to edible or biodegradable films and coatings to extend fruit shelf life and reduce microorganism spoilage. Agriculture is promising with nanobiotechnologies that improve volatile compound stability, pesticide residual effects and Aedes aegypti adhesion and repellency. Further research is needed to determine nanomaterials' toxicity and environmental impact.

In vitro Potency of Chemical Fungicides over Alternaria lini (Dey) Growth Inhibition Causing Black Bud Disease of Linseed

Linseed, the only economically significant species of family Linaceae is a dense plant with sound branches that gives rise to more production of seed per plant. It is a significant oilseed and fibre crop that grows in diverse range of climate from temperate to tropical regions of India. So, it is crucial to preserve the excellence and yield of such an oilseed crop due to its commercial significance. Linseed cultivation is impacted by a variety of fungal and bacterial diseases. Alternaria blight or often called as Black Bud Disease is one of the most important fungal diseases of this oilseed crop which causes yield loss ranging from 28-60%. The present study emphasized upon two objectives. First one is the survey of different cultivars that was conducted in various parts of Uttar Pradesh during the month of March-April, 2021-22 to assess the disease prevalence and severity of Black Bud Disease which revealed that cultivar Neelum had the highest disease intensity of 45%, while the variety Rashmi had the lowest disease intensity of 10%. Second one involves the study regarding in vitro potency of chemical fungicides that revealed the potency of three fungicides i.e. Tilt, Vitavax and Matco over 11 fungicides examined at 0.2 % concentration in fully inhibiting the growth of corresponding fungal pathogen, Alternaria lini. Rovral, Thiram, Folpet, Captan, Ridomil, Companion, Mancozeb, Zineb, Sulfex, Topsin-M, and Bavistin were the remaining fungicides in order of their inhibitory activity against the pathogen.

Evaluation of Fungicides Against Rhizoctonia bataticola (Taub) Butler Causing Dry Root Rot of Groundnut and Their Compatability with Trichoderma asperellum

The efficacy of four systemic and combination fungicides, namely Carbendazim 12% + Mancozeb 63% WP, Tebuconazole 25% WG, Hexaconazole 4% + Zineb 68% WG, and Tebuconazole 50% + Trifloxystrobin 25% WG, against Rhizoctonia bataticola, the causal agent of dry root rot in groundnut was evaluated using the poison food technique. Among the tested fungicides, Hexaconazole 4% + Zineb 68% WG exhibited the highest efficacy, with 100% inhibition of mycelial growth at all concentrations tested. Tests of compatibility of these fungicides with Trichoderma asperellum revealed that Hexaconazole 4% + Zineb 68% WG caused 38.88% of growth inhibition in T. asperellum while the other fungicides tested were totally incompatible with100 percent inhibition.

Biological Control of Groundnut Stem Rot and Collar Rot Pathogens under in vitro Conditions

The experiment was conducted under laboratory conditions by using native isolates. These were tested against stem rot (S. rolfsii) and collar rot (A. niger) pathogens of groundnut under in vitro conditions by using dual culture technique. The fungal and bacterial bioagents which are inhibitory against these pathogens were identified by 18S rRNA (fungi) and 16S rRNA (bacteria) techniques and were compared with those from the GenBank using the BLAST program. Among fungal isolates T. harzianum (MBNRT-1) was superior in inhibition of S. rolfsii and A. niger and the per cent inhibitions were 70.5% in case S. rolfsii whereas; in A. niger the inhibition was 72.9 per cent. Among native bacterial isolates the isolate B. amyloliquifaciens (MBNRB-3) and is significantly superior over the other isolates in inhibiting the pathogens S. rolfsii and A. niger under in vitro conditions and the inhibitions were 66.6 per cent and 63.0 per cent respectively. Further, compatibility of effective fungal and bacterial bioagents T. harzianum (MBNRT-1) and B. amyloliquifaciens (MBNRB-3) with six fungicides and eight herbicides indicated that among the fungicides the azoxystrobin was highly compatible with both the bioagents T. harzianum (MBNRT-1) and B. amyloliquifaciens (MBNRB-3) whereas, among the herbicides imazethapyr + imazamox was found to be compatible with both the bioagents with all the concentrations. While, tebuconazole, thiram, mancozeb+carbendazim (fungicides) and quizolofop-p-ethyl and pendimethalin (herbicides) were highly inhibitory to the T. harzianum (MBNRT-1) and B. amyloliquifaciens (MBNRB-3) under in vitro conditions.

Effect of satellite-emitted frequency sequences on Phakopsora pachyrhizi control, on soybean nutrition and yield

The obstacles in Phakopsora pachyrhizi management result especially from susceptible soybean genotypes and resistant fungal strains. The objective of the current study was to evaluate the applicability of the emission of extremely low and specific frequencies by Effatha technology in the soybean Asian rust control, nutrition, and its impact on yield. The in-vivo test followed the detached leaves method, with six treatments: frequencies 1 and 2 individually and in association; the conventional chemical treatment (fungicide azoxystrobin + benzovindiflupyr); and witnesses in presence and absence of the fungus. Frequency 1 relates to inhibition of the enzyme succinate dehydrogenase and 2 to ubiquinone oxidase. In the field, frequencies 1 and 2 associated (with the same fungicidal action of the in-vivo study); nutritional frequency; application of azoxystrobin + benzovindiflupyr + mancozeb, and control without application were evaluated. In vivo, the fungicide provided 85% control of the disease symptoms, against 65% of frequencies 1 and 2 in association, which showed a higher efficiency compared to the isolated frequencies. In the field, the rate of increase of symptoms were reduced by all treatments compared to the control. At the end of the soybean cycle, the conventional fungicide resulted in 33% severity against 56% of frequencies 1 and 2 associated, and 69.2% of the control. The emission of the frequency for increased nutrient efficiency stood out positively on yield in relation to all the other ones. The conventional application provided the highest weight of 1,000 grains, possibly a direct reflection of the better control of the disease.

Chemical control of dieback and mango malformation in a semiarid region

The São Francisco Sub medium Valley is a great mango exporter in Brazil. In this semiarid region, diseases such as dieback and mango malformation have reduced the production of this crop. In this work the effectiveness of different active ingredients (flutriafol, methyl-thiophanate, copper hydroxide and fluxapyroxad mixed with pyraclostrobin) was assessed for the control of these diseases in a mango orchard. Monthly assessments of disease incidence were carried out. There was a difference among treatments for the two diseases studied, with flutriafol as the most effective fungicide against dieback and, for the malformation, the mixture of fluxapyroxad and pyraclostrobin and methyl-thiophanate showed the best results.

The Potential Effects of Fungicides on Association of Rhizophagus irregularis with Maize and Wheat

Abstract The effect of different fungicides on mycorrhizal fungi should be investigated in different plants and environmental conditions. Thus, the purpose of this study was to appraise the effect of simultaneous fungicides application (including benomyl, rovral TS, mancozeb, and tilt) on the efficiency of Rhizophagus irregularis in cultivations of maize and wheat. This study was conducted in two separate experiments in the laboratory and greenhouse. The results of the laboratory stage showed that the use of all four fungicides significantly reduced the spore number compared to the conditions of non-use of the fungicide, although only rovral TS and mancozeb led to a significant reduction in root colonization percentage of R. irregularis. In the greenhouse, the benomyl significantly increased root dry weight in maize although tilt significantly reduced root colonization of maize with R. irregularis. The tilt and rovral TS had a positive effect and benomyl had a negative effect on wheat growth traits, but the root colonization of wheat with R. irregularis was not affected by fungicides. Generally, benomyl (2 g L-1) in maize and tilt (2 mL L-1) in wheat and rovral TS in both plants could be recommended with the combined application of R. irregularis inoculants. Therefore, depending on the type of fungicide and the host plant, the effect of the fungicide on colonization and association of mycorrhiza varies.

Modern Fungicides: Mechanisms of Action, Fungal Resistance and Phytotoxic Effects

The establishment of safe and effective methods for controlling fungal diseases is an urgent issue in agriculture and forestry. Fungicide research has provided a wide range of products with new modes of action. Extensive use of these compounds in agriculture enhances public anxiety due to the harmful potential for the environment and human health. Moreover, the phytotoxic effects of some fungicides are already recognized but still little is known about their influence on the photosynthetic apparatus and plant physiology. This review provides an understanding of the mechanisms of action of fungicides, mechanisms of fungicide resistance development, and the phenomenon of phytotoxicity.

Reaction of maize hybrids to Northern corn leaf blight and common rust, and chemical control of Northern corn leaf blight / Reação de híbridos de milho a helmintosporiose e ferrugem comum, e controle químico de helmintosporiose

Northern corn leaf blight (NCLB) and common rust are among the primary fungal diseases affecting maize production. This study aimed to evaluate the susceptibility of ten maize hybrids to NCLB and to common rust and to verify the efficiency of fungicides in the chemical control of Exserohilum turcicum. In the first experiment, hybrids Pioneer (30F53, P1630H, P2530), Monsanto (AG 8045, AG 9045), Dow AgroSciences (2A550, 2A106 and 2B587) and Syngenta (SYN7205 VIPTERA, SW 3949 TL) were used and in the experiment for effectiveness of fungicides in the control of NCLB. The efficiency of fungicides propiconazole, azoxystrobin, cyproconazole + azoxystrobin, prothioconazole + trifloxystrobin, benzovindiflupir + azoxystrobin, cyproconazole + azoxystrobin + mancozeb were tested in the Pioneer P1630H hybrid. In both experiments, the leaf disease severity (%), yield and the weight of one thousand seeds were evaluated. The experimental design was carried out in randomized blocks with four replicates. The hybrids SYN7205, P2530, SW 3949 TL, 2B587, AG 9045, 2A550, P1630H, 2A106 and AG 8025 showed the smallest areas under the common rust severity progress curve. Hybrids AG9045, 30F53, and 2A550 presented the smallest areas under the NCLB progress curve. Hybrids AG8025, 2B587, P1630H, AG9045, 2A106, 2A550, present the highest yields. The fungicides prothioconazole + trifloxystrobin present the highest chemical control efficiency for NCLB and the lowest area under the disease progress curve (AUDPC).(AU)

A helmintosporiose e a ferrugem comum estão entre as principais doenças fúngicas que afetam a produção do milho. Os objetivos desse trabalho foram avaliar a suscetibilidade de dez híbridos de milho a helmintosporiose e a ferrugem comum e verificar a eficiência de fungicidas no controle de Exserohilum turcicum. No primeiro experimento utilizaram-se os híbridos Pioneer (30F53, P1630H, P2530), Monsanto (AG 8045, AG 9045), Dow AgroSciences (2A550, 2A106 e 2B587) e Syngenta (SYN7205 VIPTERA, SW 3949 TL), e no experimento de eficiência de fungicidas no controle de helmintosporiose, testou-se a eficiência dos fungicidas propiconazol, azoxistrobina, ciproconazol + azoxistrobina, protioconazol + trifloxistrobina, benzovindiflupir + azoxistrobina, ciproconazol + azoxistrobina + mancozebe, no híbrido Pioneer P1630H. Em ambos os experimentos avaliaram-se a severidade foliar das doenças (%), o rendimento e o peso de mil sementes. O delineamento experimental foi em blocos ao acaso com quatro repetições. Os híbridos SYN7205, P2530, SW 3949 TL, 2B587, AG 9045, 2A550, P1630H, 2A106 e AG 8025 apresentam as menores áreas abaixo da curva de progresso de severidade de ferrugem comum. Os híbridos AG9045, 30F53 e 2A550 apresentam as menores áreas abaixo da curva de progresso de helmintosporiose. Os híbridos AG8025, 2B587, P1630H, AG9045, 2A106 e 2A550 apresentam os maiores rendimentos. Os fungicidas protioconazol + trifloxistrobina apresentam a maior eficiência de controle químico de helmintosporiose e a menor AACPD.(AU)

Effect of Six Fungicides against Fusarium oxysporum and F. solani Associated with Peach Seedlings Decline in Tunisian Nurseries

Aims: This study investigated the efficiency of six fungicides against Fusarium spp. associated to peach seedling decline in Tunisian nurseries. Place and Duration of Study: Department of Biological Sciences and Plant Protection, Higher Institute of Agronomy of Chott Mariem, 4042, Sousse, Tunisia, between March 2016 and June 2016. Methodology: The activity of six fungicides against Fusarium oxysporum and F. solani associated with peach seedling decline in Tunisian nurseries was evaluated in vitro and in vivo. Results: The in vitro test showed that Carbendazim was the most effective at a low dose (10 ppm) against F. solani with 84.39% of hyphal growth inhibition, while it gives 60.55% of growth inhibition against F. oxysporum at 100 ppm. The percent of growth inhibition generated by Mancozeb was between 59.02 and 90.21% at 50 and 100 ppm, respectively. The efficacy of fosetyl-Al was not important in vitro at 10, 25, 50 and 100 ppm against the two tested pathogens. Hymexazol revealed to be effective against F. oxysporumbut without effect on F. solani for all used doses. The Chinosol was effective at different doses against F. oxysporum, with 88% of growth inhibition at 50 ppm for the two tested species. Thus, the fosetyl-Al, hymexazol and chinosol are the most effective on F. oxysporum and F. solani. Carbendazim was moderately effective against F. oxysporum (40. 15%), whereas it was the most effective against F. solani (98.02%). The mancozeb and metalaxyl-M+mancozeb were the lowest effective against the two pathogens tested with percents of inhibition of 27.41% and 28.96% for F. oxysporum respectively, and 48.02% and 42.46% for F. solani, respectively. Results of in vivo test indicated that disease severity parameters of peach seedlings recorded after three months of inoculation by Fusarium spp. showed that the fosetyl-Al and metalaxyl-M + mancozeb reduced significantly root browning induced by Fusarium oxysporum by 62.55%. The mancozeb and carbendazim reduced also the root browning without significant effect. Whereas, all products didn’t reduce the severity of root browning or the vegetative sanitary states index of peach seedlings inoculated by F. solani. For the growth parameters, plants inoculated by F. oxysporum and treated by fosetyl-Al and metalaxyl-M+mancozeb increased the root weight by 34% and 24.89%, respectively. The metalaxyl-M+mancozeb improved also the plant height by 8.05% compared to the control inoculated by F. oxysporum. However, chinosol was the only product that improved plant height by 10.31% and root weight by 9.78% of plants inoculated by F. solani. Conclusion: The fungicides Alliette express (fosetyl-Al), Ridomil Gold (mancozeb+ metalaxyl-M),Dithane-M45 (mancozeb) and Prodazim (carbendazim) were the most effective in vivo against F. oxysporum associated with a peach seedling decline in Tunisian nurseries, whereas Beltanol (chinosol) is the only product that improved the seedling growth inoculated by F. solani. Thus, it will be important to test them in the future against the other genera associated with this disease like Pythium and Phytophthora species. Then, it is necessary to test them against the combination of these pathogens because the causal agent of this disease is a complex.

Rust effect estimation in soybean crosses for tolerance to Asian rust / Estimativa do efeito ferrugem em cruzamentos de soja para tolerância à ferrugem asiática

ABSTRACT: Asian soybean rust is an important disease that has deeply troubled farmers and researchers since it was first reported. The causal agent, biotrophic fungus Phakopsora pachyrhizi Sydow & P. Sydow, has found extremely favorable conditions for its dissemination in Brazil. The most characteristic symptom of infection appears in the leaves, initially on the adaxial leaf surface, as small angular points less than 1mm in diameter, together with gray-colored uredospores (spores). Management involves a set of practices that guarantee coexistence between the plant and the pathogen without significant damage to the crop. The objective of this research was to evaluate tolerance to Asian rust by estimating losses caused by natural infection in the field. Experiments with generation F4 (2014/15) plants were established in a randomized blocks design with four replicates, with two types of genotypes (crosses and parents) and two schemes for disease management using fungicides. For analysis of the data, a test was applied on two dependent samples to verify the significance of the estimate of the rust effect. With regard to grain yield and tolerance, the most outstanding crosses were 104 (USP14-01-20 × EMGOPA313) and 149 (USP93-05.552 × EMGOPA313). Crosses 147 (USP93-05552 × PI153.282) and 137 (USP70.108 × PI153.282) were graded as tolerant in the evaluation of both yield reduction and seed size. We found evidence of tolerance to Asian rust in both crosses and parents. The statistical test revealed the significance of the rust effect estimates in soybean.

RESUMO: A ferrugem asiática da soja é a doença que mais tem preocupado os produtores e pesquisadores desde sua primeira evidência. Ela é causada pelo fungo biotrófico Phakopsora pachyrhizi Sydow & P. Sydow que encontrou condições extremamente favoráveis para a sua disseminação no Brasil. O sintoma mais característico apresenta-se nas folhas, inicialmente na face adaxial, como pequenos pontos angulares com menos de um milímetro de diâmetro, juntamente com os uredósporos (esporos) de coloração acinzentada. O manejo se dá por meio de um conjunto de práticas que garanta a boa convivência entre a planta e o patógeno e sem que ocorra danos significativos à lavoura. O trabalho objetivou avaliar a tolerância à ferrugem asiática estimando as perdas causadas pela infestação natural a campo. Os experimentos com a geração F4 (2014/15) foram delineados em blocos ao acaso com quatro repetições. Foram realizadas categorias de experimentos, envolvendo dois tipos de genótipos (cruzamentos e genitores) e dois tipos de manejos de doenças com fungicidas. Para a análise dos dados foi aplicado um teste, para duas amostras dependentes, a fim de verificar a significância da estimativa do efeito ferrugem. Considerando a produtividade e a tolerância, os cruzamentos mais importantes foram 104 (USP 14-01-20 x EMGOPA 313) e 149 (USP 93-05.552 x EMGOPA 313). Os cruzamentos 147 (USP 93-05.552 x PI 153.282) e 137 (USP 70.108 x PI 153.282) foram tolerantes tanto na avaliação de redução da produtividade e do tamanho de semente. Houveram evidências de tolerância à ferrugem asiática nos cruzamentos e nos genitores. O teste estatístico revelou a significância das estimativas de efeito ferrugem em soja.

Sensitivity of two isolates of Phakopsora pachyrhizi to dithiocarmamate, chloronitril, triazoles, strobilurins, and carboxamides fungicides / Sensibilidade de Phakopsora pachyrhizi aos fungicidas ditiocarbamatos, cloronitrilas, triazóis, estrobilurinas e carboxamidas

Asian soybean rust (ASR), caused by the phytopathogen Phakopsora pachyrhizi Sydow & Sydow, is a worldwide distributed fungal disease responsible for causing damages in soybean crops [Glycine max (L.) Merril] of up to 90% of its productive potential. So far, due to limited availability of resistant varieties, fungicide application is the most widely used strategy for ASR control, although some populations of the pathogen have shown reduced sensitivity to certain active ingredients. Several methods have been described to measure the sensitivity of a fungus to a given fungicide, or even the fungitoxicity of a chemical. The most used tests are spore germination in wateragar medium and evaluation of disease severity in detached soybean leaves. Experiments were carried out with Brazilian populations of the pathogen: one from Uberlândia - MG and the other from Chapadão do Sul - MS, following the mentioned methodologies. The results showed the reduction of benzovindiflupyr efficiency in relation to spore germination and disease severity for the MS population, as also did fluxapyroxad, cyproconazole, and tebuconazole. Multisite fungicides (chlorothalonil, copper oxychloride, and mancozeb) may be used in the management of ASR resistance in the fields of Brazil associated with strobilurins, triazoles, and carboxamides. The efficiency of the main active ingredient tested depends on the formulation and others molecules used in the commercial product.

A ferrugem asiática da soja (FAS), causada pelo fitopatógeno Phakopsora pachyrhizi Sydow & Sydow, é uma doença fúngica distribuída mundialmente e responsável por causar danos na cultura da soja [Glycine max (L.) Merril], em até 90% do potencial produtivo. Até agora, devido à limitada disponibilidade de variedades resistentes, a aplicação de fungicida é a estratégia mais utilizada para controlar a FAS, embora algumas populações do patógeno tenham demonstrado menor sensibilidade a determinados ingredientes ativos. Vários métodos foram descritos para medir a sensibilidade de um fungo a um dado fungicida, ou para monitorar sua redução ou perda de eficácia, ou mesmo a fungitoxicidade de um produto químico. Os testes mais utilizados são a germinação de esporos in vitro e a severidade da doença (%) em folhas de soja destacadas. Baseando-se nessas metodologias, foram realizados ensaios com populações do patógeno oriundas de Uberlândia - MG e do Chapadão do Sul - MS. Os resultados mostraram a redução da eficiência de benzovindiflupyr em relação à germinação e à severidade de doença para a população de Chapadão do Sul - MS. O mesmo comportamento foi obtido para os ingredientes ativos fluxapyroxad, cyproconazole e tebuconazole. Os fungicidas multissítios (clorotalonil, oxicloreto de cobre e mancozeb) podem ser utilizados no manejo da resistência à FAS nas lavouras do Brasil associados às estrobilurinas, triazóis e carboxamidas. A eficiência do principal ingrediente ativo estudado depende dos outros ingredientes ativos ou fungicidas associados na formulação comercial.

Caracterización química y evaluación de la actividad antifúngica del aceite esencial foliar de Lippia alba contra Colletotrichum gloeosporioides

El objetivo de este estudio fue caracterizar y evaluar in vitro la eficiencia del aceite esencial foliar de Lippia alba contra Colletotrichum gloeosporioides. Se extrajo el aceite esencial a partir de las hojas mediante el método de hidrodestilación asistida por microondas (MWHD) y se identificaron sus metabolitos mediante una cromatografía de gases acoplada a espectrometría de masas (GC/MS). La evaluación in vitro se realizó empleando 4 concentraciones del aceite esencial (500, 1000, 3000 y 10000 ppm) diluidas en acetona; se utilizó un control positivo con Benomil 1 g/L, un control negativo con acetona y un testigo absoluto; la eficiencia del aceite se midió mediante el porcentaje de índice antifúngico (%I.A). El componente mayoritario en el aceite esencial fue el citral (34.62 a 40.03%) y que el mayor %I.A se encontró a la concentración de 10000 ppm (97.8%), muy similar a la del Benomil (100%). Lo anterior demostraría la eficacia del aceite esencial de L. alba para controlar a C. gloeosporioides, y su posible uso como fungicida biológico.

The aim of this study was to characterize and evaluate the in vitro efficiency of leaf essential oil of Lippia alba against Colletotrichum gloeosporioides. Essential oil from the leaves was extracted by the method of assisted microwave hydrodistillation (MWHD) and metabolites were identified by gas chromatography coupled to mass spectrometry (GC/ MS). The in vitro evaluation was performed using 4 concentrations of essential oil (500, 1000, 3000 and 10000 ppm) diluted in acetone; positive control with Benomyl 1 g /L, a negative control with acetone and absolute control was used; oil efficiency was measured by the percentage of antifungal index (% IA). It was found that the major component was in the essential oil citral (34.62 to 40.03%) and the highest %I.A was found to 10000 ppm concentration (97.8%) very similar to Benomyl (100%). This would demonstrate the efficacy of the L. alba essential oil to control C. gloeosporioides, and its possible use as a biological fungicide.

Sensibilidad in vitro de Trichoconiella padwickii a diversos principios activos usados como fungicidas en el cultivo del arroz / In vitro susceptibility of Trichoconiella padwickii to various active ingredients used as fungicides in the cultivation of rice

El objetivo de este trabajo fue evaluar in vitro la sensibilidad micelial de Trichoconiella padwickii a diferentes principios activos por medio del cálculo de la concentración inhibitoria media (CI50). Para ello se realizaron siembras de discos de inóculo en agar poroto con distintas concentraciones (0,1; 1; 10; 30, 50; 100 y 1.000 mg/l) de diversos fungicidas. A los 7 días se midió el diámetro de crecimiento de la colonia (cm). Los datos obtenidos se ajustaron a modelos de regresión no lineal. La sensibilidad se clasificó utilizando la escala de Edgington. Los resultados obtenidos demuestran que el patógeno es muy sensible a los productos que actúan sobre la cadena respiratoria (quinone outside inhibitors QoI y succinate dehydrogenase inhibitors SDHI) y la membrana celular (multisitio), y moderadamente sensible a los que interfieren en la división celular (metil benzimidazol carbamatos MBC), en la síntesis de ácidos nucleicos (fenilamidas PA) y en la transducción de la señal osmótica (actividad multisitio). Este trabajo es el primer antecedente sobre la sensibilidad in vitro de T. padwickii a principios activos fungicidas.

The aim of this study was to evaluate in vitro the mycelial susceptibility of Trichoconiella padwickii to different active ingredients through average median concentration IC50 calculation. Inoculum disks were seeded on bean agar at different concentrations (0.1; 1; 10; 30, 50; 100 and 1000 mg/l) of various fungicides. After seven days the colony diameter was measured. The data obtained were fitted to nonlinear regression models. Susceptibility was classified using the scale proposed by Edgington. The results show that the pathogen is very sensitive to products that act on the respiratory chain (quinone outside inhibitors QoI and succinate dehydrogenase inhibitors SDHI) and cell membrane (multi-site contact activity), and moderately sensitive to those products interfering with cell division (methyl benzimidazole carbamates MBC), synthesis of nucleic acids (phenylamides PA) and osmotic signal transduction (multi-site contact activity). This work is the first record on the sensitivity of T. padwickii.

The Effect of Fungicides on Mycelial Growth and Conidial Germination of the Ginseng Root Rot Fungus, Cylindrocarpon destructans

Ginseng root rot caused by Cylindrocarpon destructans is the most destructive disease of ginseng. Six different fungicides (thiophanate-methyl, benomyl, prochloraz, mancozeb, azoxystrobin, and iprodione) were selected to evaluate the inhibitory effect on the mycelial growth and conidial germination of C. destructans isolates. Benomyl and prochloraz were found to be the most effective fungicides in inhibiting mycelial growth of all tested isolates, showing 64.7% to 100% inhibition at a concentration of 10 µg/mL, whereas thiophanate-methyl was the least effective fungicide, showing less than 50% inhibition even at a higher concentration of 100 µg/mL. The tested fungicides exhibited less than 20% inhibition of conidium germination at concentrations of 0.01, 0.1, and 1 µg/mL. However, the inhibition effect of mancozeb on condium germination of C. destructans was significantly increased to 92% to 99% at a higher concentration of 100 µg/mL, while the others still showed no higher than 30% inhibition.

Management of blight of bell pepper (Capsicum annuum var. grossum) caused by Drechslera bicolor

Abstract Sweet or bell pepper is a member of the Solanaceae family and is regarded as one of the most popular and nutritious vegetable. Blight, in the form of leaf and fruit blight, has been observed to infect bell pepper crops cultivated at the horticulture farm in Rajasthan College of Agriculture, Udaipur, India. Based on disease severity, we attempted to curb this newly emerged problem using different fungicides, plant extracts, bio-control agents, and commercial botanicals against the fungus in laboratory and pot experiments. Bio-control agent Trichoderma viride and plant growth promoting Rhizobacteria (PGPR) isolate Neist-2 were found to be quite effective against bell pepper blight. All evaluated fungicides, botanicals, commercial botanicals, and bio-control agents in vitro were further studied as seed dressers and two foliar sprays at ten days interval in pot experiments. The combinations of Vitavax, PGPR isolate Neist-2, and Mehandi extract were found to be very effective against bell pepper blight followed by Vitavax, T. viride, and Mehandi extract used individually. All treatments in the pot experiments were found to significantly reduce seedling mortality and enhance plant biomass of bell pepper. Thus, these experimental findings suggest that a better integrated management of bell pepper blight could be achieved by conducting field trials in major bell pepper- and chilli-cultivated areas of the state. Besides fungicides, different botanicals and commercial botanicals also seem to be promising treatment options. Therefore, the outcome of the present study provides an alternate option of fungicide use in minimizing loss caused by Drechslera bicolor.

Reduction of white mold level on soybean by fungicide management strategies / Redução do nível de mofo-branco na soja pelo manejo de fungicidas

The objective of this study was to verify the efficiency of the control of white mold on soybean with the use of fungicides applied alone and in rotation, at different growth stages and in a mixture of two active ingredients at three locations: Arapoti, PR, Mauá-da-Serra, PR and Pinhão, PR, Brazil. The fungicides used were carbendazim (Ca), thiophanate methyl (Tm), procymidone (Pr) and fluazinam (Fl). The experiments consisted on 17 treatments and 4 replications in a randomized block design. The analyzed variables were severity, incidence, number of sclerotia and yield. Mauá-da-Serra and Pinhão presented the highest incidences (31% and 29.8% in the control, respectively). At these two locations most of treatments with fungicides decreased the incidence and production of sclerotia, when compared to control; however, no differences in terms of yield were observed. Arapoti presented the lowest incidence (15.8% in the control) where most of treatments with fungicides did not present differences for the variables incidence, production of sclerotia and yield, when compared to the control. No differences were also observed for severity in any of three locations. In conclusion, fungicides applied in soybean areas with historically white mold incidence up to 31% can reduce the disease incidence and sclerotia production levels.

O objetivo deste estudo foi o de verificar a eficiência de controle do mofo-branco na soja com o uso de diferentes fungicidas aplicados isoladamente, alternados, em diferentes estádios fenológicos e em mistura de dois princípios ativos, em três locais: Arapoti/PR, Mauá-da-Serra/PR e Pinhão/PR, Brasil. Os fungicidas utilizados foram carbendazim (Ca), tiofanato metílico (Tm), fluazinam (Fl) e procimidona (Pr). Os experimentos foram compostos por 17 tratamentos e 4 repetições distribuídas em blocos aleatorizados. As variáveis analisadas foram incidência, severidade, produção de escleródios e o rendimento da cultura. Mauá-da-Serra e Pinhão apresentaram as maiores incidências, 31% e 29,8% no tratamento controle, respectivamente, onde a maioria dos tratamentos com fungicidas proporcionou menor incidência e produção de escleródios, quando comparados ao controle, porém sem diferenças quanto ao rendimento. Em Arapoti foi observada a menor incidência, 15,8% no controle, onde a maioria dos tratamentos com fungicidas não apresentou diferenças para incidência, produção de escleródios e rendimento, quando comparados ao controle. Em nenhum dos três locais foram verificadas diferenças entre os tratamentos e o controle para a variável severidade. Como conclusão, fungicidas aplicados em áreas de soja com histórico de incidência de mofo-branco de até 31% podem reduzir a incidência da doença e o nível de produção de escleródios.