ABSTRACT
Evaluation of the relative efficacy of powdered leaf extracts of Aloe vera(Linn) and Aloe schweinfurthii(Baker) in the control of some plant pathogens was undertaken in this work. Antimicrobial activities ofthe extracts obtained using cold water, hot water and ethanol were tested against four fungal spp., namely, Alternaria solani,Colletotrichum lindemuthianum, Sclerotium rolfsiiand Trichophyton rubrum. The phytochemical screening of the leaf extracts of the two aloe species revealed the presence of bioactive compounds such as alkaloids, tannins, saponins, flavonoids, cardiac glycosides, phytates and oxalates. The extracts were observed to exhibit varying inhibitory effects on the selected fungi. Ethanolic extract of A. veraat 50mg/ml and 100mg/ml had the greatest impact on A. solaniand C. lindemuthianum respectively.Similarly, cold water extract of A. schweinfurthiiat 100mg/ml was the most effective against S. rolfsiiandT. rubrum.However, hot water extract of A. vera wasleast effective against C. lindemuthianum. Also, the efficacy of cold water extract of A. schweinfurthii at 50mg/mlwas very low against T. rubrumand A. solani. The hot water extract of A. schweinfurthii at 20mg/ml also showed the least effect against S. rolfsii. Consequently, extracts from both Aloe species can be recommended in the management of the four fungal pathogens evaluated in this study. It is hoped that in no distant future, botanical fungicides would be developed from the two Aloe species
ABSTRACT
Objective: To study the chemical constituents of endophytic fungus Alternaria solani from Aconitum transsectum. Methods: The compounds were isolated and purified by column chromatography , and their structures were elucidated based on the spectroscopic analysis (1H-NMR, 13C-NMR and MS).Results:Totally 15 compounds were isolated from A.solani and characterized as 20-hydroxyl-ergosta-4,6,8(14),22-tetraen-3-one(1),ergone(2),stellasterin(3),episterol(4),ergosterol peroxide(5),cyclo(D)-Pro-(D)-Leu(6),cyclo-(L-Val-L-Pro)(7),cyclo-(S-Pro-S-Ile)(8),tentoxin(9),porrotoxin(10),7-dehydroxyl-zinniol(11),zinniol (12),8-zinniol methyl ether (13),3-methoxy-4-methyl-5-(3′,3′-dimethylallyloxy)-2-methoxymethyl benzoic acid (14) and pseudo-monas aeruginosa H2-sesquiterpene lactone (15).Conclusion: Totally 15 compounds are isolated from endophytic fungus Alternaria solani, and compounds 2-10 and 12-15 are isolated for the first time .
ABSTRACT
ABSTRACT: Early blight is one of the most important fungal diseases of potato. The objective of this study was to evaluate the in vitro reaction of potato genotypes to the severity of early blight and compare the species Alternaria solani and Alternaria grandis , etiologic agents of disease, through the evaluation of physiological characteristics. Twenty-two genotypes of the Potato Breeding Program at UFLA, two cultivars, Aracy and Bintje, patterns of resistance and susceptibility, respectively were evaluated. For inoculation, three isolates of A. grandis and two isolates of A. solani were used. Plantlets obtained in vitro were inoculated with a 5mm diameter mycelial disk of isolates Alternaria spp. of. These were incubated in severity and classified according to the rating scale. Isolates of Alternaria spp. were evaluated for mycelial growth index (MGI) and for formation of mycelial compatibility groups (MCG). The methodology for evaluating the in vitro reaction of genotypes to severity of early blight was efficient for both isolates. The isolates of A. solani and A. grandis were similar in their aggressiveness. The isolates of A. grandis MGI's had higher, and therefore mycelium grew faster when compared to those isolated from A. solani . The occurrence of mycelial compatibility among isolates of A. solani and A. grandis indicated the possible occurrence of parasexual cycle.
RESUMO: A pinta preta é uma das doenças fúngicas mais importantes da cultura da batata. O objetivo deste trabalho foi avaliar, in vitro, a reação de genótipos de batata à pinta-preta e comparar as espécies Alternaria grandis e Alternaria solani , por meio da avaliação de características fisiológicas. Foram avaliados 22 genótipos do Programa de Melhoramento Genético de Batata da UFLA, sendo duas cultivares, padrões de resistência e suscetibilidade. Foram inoculados três isolados de A. grandis e dois de A. solani . As plântulas, obtidas in vitro, foram inoculadas com os isolados de Alternaria spp., incubadas e classificadas quanto à severidade. Os isolados de Alternaria spp. foram avaliados quanto ao índice de velocidade de crescimento micelial (IVCM) e a formação de grupos de compatibilidade micelial (GCM). A metodologia de avaliação precoce in vitro da reação dos genótipos à severidade da pinta-preta foi eficiente para os isolados de ambas as espécies de Alternaria . Os isolados de A. grandis e A. solani apresentaram comportamento semelhante quanto à agressividade. Os isolados de A. grandis apresentaram IVCMs superiores e, portanto, crescimento micelial mais rápido. A ocorrência de compatibilidade micelial entre isolados de A. grandis e A. solani indica a possibilidade de ocorrência do ciclo parassexual.
ABSTRACT
A requeima (Phytophthora infestans) e a pinta preta (Alternaria solani) estão entre as doenças mais frequentes e destrutivas da cultura da batata. Com o objetivo de avaliar a ação de diferentes grupos fungicidas no controle dessas doenças, foram realizados dois experimentos em cultivo comercial de batata (cultivares Agata e Monalisa), localizados em Pilar do Sul, São Paulo, nas safras 2008 e 2009. O delineamento experimental utilizado foi o de blocos ao acaso, com 4 repetições, sendo cada parcela de 20 m2. As aplicações foram realizadas com um pulverizador costal, munido de barra de aplicação e pressão constante de 3 Bar. O volume de aplicação variou de 300 a 500 L.ha-1 em função do desenvolvimento da cultura. As variáveis avaliadas para as duas doenças foram: severidade em folhas, área abaixo da curva de progresso da doença (AACPD), produtividade total e comercial, e classificação de tubérculos. Os menores níveis de doença e aumentos significativos na produtividade comercial e qualidade de tubérculos foram observados nas parcelas tratadas com fluopicolide + propamocarbe, dimetomorfe + ametoctradina, mandipropamida + clorotalonil, mandipropamida, fenamidona + propamocarbe, bentiavalicarbe + fluazinam, seguidos de dimetomorfe + clorotalonil, mefenoxam + clorotalonil e famoxadona + cimoxanil + mancozebe para requeima, e azoxistrobina + difenoconazol, picoxistrobina, piraclostrobina + metconazol, trifloxistrobina + tebuconazol, azoxistrobina, boscalida + piraclostrobina, iprodiona + pirimetanil e ciprodinil para pinta preta.(AU)
Late blight (Phytophthora infestans) and early blight (Alternaria solani) are among the most current and destructive diseases of potato. With the aim of evaluating the efficiency of different fungicides in the control of both diseases, two experiments were carried out in commercial potato crops (cultivars Agata and Monalisa) in Pilar do Sul, São Paulo State, Brazil, during 2008 and 2009 cropping season. Randomized block designs were used, with 4 replications and each parcel of 20 m2. Applications were carried out using coastal sprayer with spray-bar under constant pressure of 3 Bar. The application volume varied from 300 to 500 L per hectare according to the crop development. The evaluated variables for both diseases were: severity on leaves, area under disease progress curve (AUDPC), total and commercial yield, and classification of tubers. For late blight, the lower severity levels and significant increases in commercial yield and quality tubers were observed on the rows treated with fluopicolide + propamocarb, dimetomorph + ametoctradin, mandipropamid + chlorothalonil, mandipropamid, fenamidone + propamocarb, benthiavalicarb + fluazinam, followed by dimetomorph + chlorothalonil, mefenoxam + chlorothalonil e famoxadone + cymoxanil + mancozeb and, for early blight, azoxystrobin + difenoconazole, picoxystrobin, pyraclostrobin +metconazole, trifloxystrobin + tebuconazole, azoxystrobin, boscalid + pyraclostrobin, iprodione + pyrimethanil and cyprodinil.(AU)
Subject(s)
Solanum tuberosum , Alternaria , Phytophthora infestans , FungiABSTRACT
Early blight of tomato incited by Alternaria solani is an economically significant disease especially in commercial tomato cultivation under greenhouse and field conditions. Since, A. solani is a shy sporulator, the present investigation was taken to assess the optimum in vitro conditons for growth and sporulation of early blight pathogen. Ten A. solani isolates obtained from diseased leaf samples collected different crop growing areas of India were used in the present study. The effect of different incubation periods, fluorescent light, cold-water treatment and media were evaluated. Our results revealed maximum sporulation of A. solani on tomato fruit extract agar medium (TFEA) under continuous light for 7 days at 250C, followed by cold-water treatment and further incubated in darkness at 200C for 48 h. The sporulation of test pathogen was however sparse on V-8 juice agar. Further, the A. solani isolates on V-8 juice agar did not respond to the treatments imposed. Among the isolates, JAS (Jhajjar) isolate, that is more versatile in its ability to produce spores recorded irregular margin with abundant aerial mycelium.
ABSTRACT
O objetivo do presente trabalho foi selecionar clones de batata com elevado desempenho agronômico e resistência à pinta preta e aos vírus X e Y. Para tanto, foram realizados 57 cruzamentos entre clones portadores dos alelos Ry adg e Rx1, e a cultivar 'Chiquita', resistente à pinta preta (Alternaria solani). Na safra das águas de 2004, 57 famílias clonais foram avaliadas em campo e 331 clones selecionados considerando a aparência de tubérculos. Desse total de clones, avaliados em mais dois experimentos no verão de 2005, 180 foram selecionados por meio do marcador SCAR RYSC3 como portadores do alelo Ry adg,. Também foram realizadas uma avaliação de desempenho agronômico na safra de inverno de 2006 e uma avaliação de resistência à pinta preta nas safras de verão de 2007 e 2008. Paralelamente, foi utilizado um marcador CAPS visando à seleção de clones portadores do gene Rx1. Dessa forma, combinando os resultados dos marcadores moleculares com os de campo, agrupados via índices de seleção, foi possível selecionar 20 clones de alto desempenho agronômico, resistentes à pinta preta e portadores do alelo Ry adg. Devido a problemas apresentados pelo marcador CAPS, apenas sete destes foram analisados e um identificado como portador do alelo Rx1.
The purpose of this study was to select potato clones with high agronomic performance and resistant to early blight, Potato Virus Y (PVY) and Potato Virus X (PVX). Crossings were done among progenitors carrying the Ry adg and Rx1 alleles for resistance to PVY and PVX and the cultivar 'Chiquita', which presents high levels of resistance to early blight (Alternaria solani). In the rainy season of 2004, 57 clonal families were evaluated in the field and 331 clones were selected based on tuber appearance. These clones were field evaluated in two trials in the rainy season of 2005 and 180 clones were selected for Ry adg allele with the SCAR marker designed RYSC3. Another agronomic evaluation was done in the winter season of 2006 and early blight was evaluated in the rainy seasons of 2007 and 2008. Simultaneously a CAPS marker was used to select for the presence of Rx1 allele. Combining the results from these experiments we were able to select 20 clones presenting high agronomic performance, resistance to early blight and carrying the Ry adg allele. The use of CAPS marker has practical difficulties due to production of poor amplification products to be digested with the DdeI enzyme and should be changed for another marker which shows more efficiency.
ABSTRACT
Background: homeopathy is a means permitted in organic agriculture to control disease and plagues; biotherapics are a practical means for farmers to intervene on the health of plants in agro-ecological systems of production. Aims: to establish whether a biotherapic of A. solani may interfere on the in vitro development of the fungus and whether it affects the severity of early blight on tomato-plants in greenhouse. Methods: the effect of the biotherapic on the fungus was evaluated through the percentage of germinated spores under microscope and the growth of colonies in a culture medium. Treatments used were: biotherapic 26cH, 27cH, 28cH, 29cH and 30cH; sterilized distilled water; and diluted and agitated hydroalcoholic solution. The effect of the biotherapic on the development of disease was evaluated in 4 experiments in greenhouse. Plants were kept in vases and subjected to artificial inoculation of the fungus after the application of treatments. Evaluation of disease was carried out through diagrammatic scale. Results: no treatment affected the germination of spores or the development of fungus colonies in the culture medium. In the first test, treatment 26cH differed from water in Tukey?s test at 5% but did not differed from diluted and agitated hydroalcoholic solution. In the second test, treatments 27cH and 28cH showed significant difference from both water and hydroalcoholic solution with an average control of disease of 57% and 62% respectively. The other 2 tests did nor exhibit any significant effect. Conclusions: there was no direct effect of the biotherapic on the fungus, but there was an effect on the severity of the disease. Factors affecting the efficiency of the biotherapic must be better understood before it can be recommended to farmers for the management of early blight in tomato-plants.
Introdução: a homeopatia é um recurso permitido na agricultura orgânica, para o controle de doenças e pragas; bioterápicos constituem numa maneira prática para produtores intervirem na saúde de plantes, em sistemas de produção agro-ecológico. Plantas de tomate podem ser afetadas por várias doenças [...] Objetivos: verificar se o bioterápico A. solani pode interferer no desenvolvimento in vitro do fungo e se afeta a severidade da pinta-preta em plantas de tomates produzidas em estufa. Metodos: o efeito do bioterápico sobre o fungo foi avaliado através da porcentagem de esporos germinados, observados por microscopia e pelo crescimento de colônias em meio de cultura. Os tratamentos usados foram: bioterápico 26cH, 27cH, 28cH, 29cH e 30cH; água deslitada esterelizada; solução hidroalcoólica diluída e agitada. O efeito do bioterápico no desenvolvimento da doença foi avaliado em 4 experimentos realizados em estufa. As plantas foram mantidas em vasos e submetidas à inoculação artificial do fungo, após a aplicação dos tratamentos. A doença foi avaliada usando-se escalas diagramáticas. Resultados: nenhum tratamento afetou a germinação de esporos ou o desenvolvimento de colônias de fungos, em meio de cultura. No primeiro experimento, o tratamento 26cH diferiu da água (teste de Tukey a 5%) mas não da solução hidroalcoólica diluída e agitada. No segundo, os tratamentos 27cH e 28cH apresentam diferenças significativas tanto em relação à água quanto à solução hidroalcoólica, com um controle da doença da ordem de 57% e 62% respectamente. Os outros 2 experimentos não apresentaram efeitos significativos. Conclusões: não há efeito direto do bioterápico no fungo, porém existe diferença na severidade da doença. Os fatores que afetam a eficiência do bioterápico devem ser melhor entendidos, antes de que sejam recomendados aos produtores, para o controle da pinta-preta em tomateiros.
Introducción: la garrapata del ganado Rhipicephalus (Boophilus) microplus produce serios problemas a los hacenderos brasileños especialmente porque desarrolla rápidamente resistencia a los agentes pesticidas. Por este motivo, asociado a otros factores como contaminación ambiental, humana y animal y los costos, se buscan abordajes alternativos. Objetivos: este estudio buscó evaluar la eficiencia de un bioterápico preparado de garrapatas en vacas infestadas. Métodos: 34 vacas lecheras de raza holandesa fueron divididas en 2 grupos; uno recibió 100 mg/día de suplemento mineral impregnado con bioterápico 12cH durante 6 meses y después, en días alternados hasta completar 28 meses de tratamiento; el otro recibió apenas el suplemento mineral (control). Después de 28 meses de tratamiento, garrapatas hembra ingurgitadas fueron recogidas en ambos grupos, contadas y pesadas; fueron realizados pruebas in vitro para medir la masa de garrapatas; la masa de huevos, la tasa de eclosión de huevos y la eficiencia reproductiva. Resultados: hubo diferencias significativas entre los 2 grupos en todos los parámetros evaluados ? masa de garrapatas (p=0,0008), masa de huevos (p=0,0044), tasa de eclosión de huevos (p=0,0017) y eficiencia reproductiva (p=0,0044). Conclusión: el tratamiento con bioterápico de garrapata redujo significativamente la masa de hembras ingurgitadas y la deposición y eclosión de huevos, resultando en disminución de la eficacia reproductiva de las garrapatas.
Subject(s)
Organic Agriculture , Alternaria , Biotherapics , Isotherapy , Solanum lycopersicumABSTRACT
Strong inhibition of Bacillus subtilis strain NJ-18 on mycelia growth of Alternaria solani was observed in the antagonistic tests by cylinder plate methods, and the inhibition width was 21.5 mm. Observation under microscope found that the supernatant of fermentation from NJ-18 could make the pathogen hyphae cells malformed and swelled, and consequently the growth of the pathogen was inhibited. Determining of the colonization in potato plants by the signed rifampicin-resistance in NJ-18 showed that it could colonize well in the plants, the colonization quantity of NJ-18 in the root and stem of the potato detected 30 days after fermentation irrigation was 103 CFU/g plant’s fresh weight. In pot experiment, we inoculated the tomato plants with the spore suspensions of Alternaria solani after spraying the fermentation of NJ-18, the results were investigated in 14 days and the efficacy in controlling the disease was 72.9%, which was significantly higher than 45.7%, the efficacy resulted from spray treatment of 2000 fold dilution of 50% iprodione wetable powder.