Mycosphaerella Leaf Spot Research Articles

Epidemiology of Mycosphaerella Leaf Spot and Powdery Mildew and Agronomic Parameters of Strawberry Cultivars and Genotypes in the Highland Region of Southern Brazil

Epidemiology of Mycosphaerella Leaf Spot and Powdery Mildew and Agronomic Parameters of Strawberry Cultivars and Genotypes in the Highland Region of Southern Brazil

New record occurrence of mycosphaerella leaf spot of eucalyptus in Himachal Pradesh

A study on occurrence and distribution of Mycosphaerella leaf spot of Eucalyptus was conducted at Solan district of Himachal Pradesh during August, 2015 to December, 2015. On the basis of the morphological characteristics, the fungus was identified as Mycosphaerella cryptica and Mycosphaerella marksii which produced symptoms like necrotic spots and patches on leaves and presence of crinkled and distorted foliage. Ascopores of M. cryptica and M. marksii are hyaline, with one septum, fusiform to tunecate and whose size varies from 12-16 x 2-4 μm and 11-14 x 2-3 μm, respectively.

Impact of the extension of black leaf streak disease on banana susceptibility to post-harvest diseases

Impact of the extension of black leaf streak disease on banana susceptibility to post-harvest diseases. Abstract - Introduction. The susceptibility of banana fruit to crown rot and anthracnose, the two main banana post-harvest diseases, is influenced by many pre-harvest abiotic factors. Mycosphaerella leaf spot diseases (MLSD) of bananas are biotic pre-harvest factors, which have an influence on fruit physiology. The fruit's susceptibility to post-harvest diseases may also be influenced by foliar diseases caused by M. fijiensis, responsible for black leaf streak disease (BLSD), and M. musicola, which causes sigatoka disease (SD). The aim of our study was to determine the influence of these biotic pre-harvest factors on banana fruit's susceptibility to crown rot and anthracnose. Materials and methods. A disease severity gradient was established in two experimental fields (Cameroon for BLSD and Guadeloupe for SD) where, at the flowering stage, six different levels of MLSD severity were selected. Fruit susceptibility was determined through necrotic surface assessments after artificial inoculation by Colletotrichum musae on the 3rd hand of harvested bunches. Results and discussion. BLSD significantly influenced banana sensitivity to crown rot (P 0.05) on banana susceptibility to either post-harvest disease. These results are discussed with emphasis on the influence of variations in the source-sink ratio on fruit physiology. The influence of BLSD on crown rot disease suggests the need to take into account the management of these foliar diseases for an alternative control method of post-harvest diseases through integrated pest management programs. Cameroon / Guadeloupe / Musa / fruits / Mycosphaerella fijiensis / Mycosphaerella musicola / black sigatoka / black leaf streak disease / anthracnoses / crown rots Impact de l'extension de la maladie des raies noires sur la sensibilite des bananes aux maladies post-recolte.

Avaliação de extrato de algas no progresso temporal da mancha de Mycosphaerella em cultivares de morangueiro

Em morangueiros, a mancha das folhas, causada por Mycosphaerella fragariae, é uma das doenças mais comuns na cultura, o que torna importantes os estudos de controle alternativo e de cultivares, sobre o progresso da epidemia. Em busca de práticas alternativas para seu controle, avaliou-se o efeito de cultivares de morangueiro e do extrato da alga Ascophyllum nodosum, na expressão dos sintomas de mycosphaerella, além de avaliar o ajuste de modelos de crescimento para o progresso temporal da incidência e severidade da doença. Utilizou-se o extrato de algas a 29%, na dose de 2 L ha-1, aplicado no solo, na folha e em ambos. As cultivares Dover, Toyonoka, Albion, Camarosa, Ventana, Campinas, Tudla e Camino Real foram avaliadas, quinzenalmente, quanto a incidência e severidade da doença. Utilizou-se o delineamento inteiramente casualizado, com parcelas subdivididas e três repetições. Com os dados de incidência e severidade, calculou-se a área abaixo da curva de progresso da doença e utilizou-se a análise de variância para avaliar o efeito de cultivares e do extrato de algas. Aos dados do progresso temporal da incidência e da severidade, em cada cultivar, foram ajustados os modelos monomolecular, logístico e de Gompertz. O extrato de algas não apresentou efeito ou interação com cultivares, no controle da mycosphaerella. Houve efeito de cultivar com menor intensidade da doença, em Albion e Ventana, devido, principalmente, ao atraso na epidemia, pela redução do inóculo inicial efetivo. Aos dados de progresso temporal da incidência e da severidade ajustaram-se, respectivamente, os modelos logístico e monomolecular, para todas as cultivares.

DIAGNOSIS LIMA PENYAKIT UTAMA KARENA JAMUR PADA 100 KULTIVAR BIBIT PISANG

The research which aimed to identify main pathogenic fungi of 100 banana seedling cultivars and their disease intensity was carried out at the Laboratory of Plant Disease, Faculty of Agriculture, Jenderal Soedirman University with samples and field data taking at Indonesian Insitute of Science Bogor. This descriptive research was started by taking samples and field data followed by identification of pathogenic fungi at the laboratory. Variables observed were disease symptoms, colony and pathogenic morphology, kinds of the pathogen, disease intensity, and physical data. Result of the research showed that there were five main pathogenic fungi of the banana seedlings, i.e., Fusarium oxysporum Schlecht. f.sp. cubense, causing Fusarium wilt; Mychosphaerella musicola Mulder, causing Mycosphaerella leaf spot or Sigatoka; Cordana musae (Zimm.) Hohn., causing Cordana leaf spot; Curvularia lunata, causing leaf spot; and Cladosporium musae Mason, causing speckle. From 100 banana seedling cultivars observed, Fusarium oxysporum f.sp. cubense was the most frequently found with the intensity of 1.4-72%, followed by Curvularia lunata, Mychosphaerella musicola, Cladosporium Musae, and Cordana musae with the intensity of 1-32, 2-18, 2-24, and 3-23%, respectively.

Development of expressed sequence tag and expressed sequence tag–simple sequence repeat marker resources for Musa acuminata

Banana (Musa acuminata) is a crop contributing to global food security. Many varieties lack resistance to biotic stresses, due to sterility and narrow genetic background. The objective of this study was to develop an expressed sequence tag (EST) database of transcripts expressed during compatible and incompatible banana-Mycosphaerella fijiensis (Mf) interactions. Black leaf streak disease (BLSD), caused by Mf, is a destructive disease of banana. Microsatellite markers were developed as a resource for crop improvement. cDNA libraries were constructed from in vitro-infected leaves from BLSD-resistant M. acuminata ssp. burmaniccoides Calcutta 4 (MAC4) and susceptible M. acuminata cv. Cavendish Grande Naine (MACV). Clones were 5'-end Sanger sequenced, ESTs assembled with TGICL and unigenes annotated using BLAST, Blast2GO and InterProScan. Mreps was used to screen for simple sequence repeats (SSRs), with markers evaluated for polymorphism using 20 diploid (AA) M. acuminata accessions contrasting in resistance to Mycosphaerella leaf spot diseases. A total of 9333 high-quality ESTs were obtained for MAC4 and 3964 for MACV, which assembled into 3995 unigenes. Of these, 2592 displayed homology to genes encoding proteins with known or putative function, and 266 to genes encoding proteins with unknown function. Gene ontology (GO) classification identified 543 GO terms, 2300 unigenes were assigned to EuKaryotic orthologous group categories and 312 mapped to Kyoto Encyclopedia of Genes and Genomes pathways. A total of 624 SSR loci were identified, with trinucleotide repeat motifs the most abundant in MAC4 (54.1 %) and MACV (57.6 %). Polymorphism across M. acuminata accessions was observed with 75 markers. Alleles per polymorphic locus ranged from 2 to 8, totalling 289. The polymorphism information content ranged from 0.08 to 0.81. This EST collection offers a resource for studying functional genes, including transcripts expressed in banana-Mf interactions. Markers are applicable for genetic mapping, diversity characterization and marker-assisted breeding.

Controle de doenças foliares e de flores e qualidade pós-colheita do morangueiro tratado com Saccharomyces cerevisiae

O efeito de diferentes preparações de Saccharomyces cerevisiae foi avaliado sobre o desenvolvimento das doenças do morangueiro, como mancha-de-micosferela (Mycosphaerella fragariae), mancha-de-dendrofoma (Dendrophoma obscurans) e flor-preta (Colletotrichum acutatum) além da qualidade pós-colheita dos frutos. O trabalho foi realizado entre 2004 e 2005 na Universidade Tecnológica Federal do Paraná, Campus Dois Vizinhos. Os tratamentos consistiram de pulverizações semanais de cinco diferentes preparados a partir da levedura S. cerevisiae: suspensão com fermento biológico fresco comercial, suspensão de células de levedura, suspensão autoclavada de células, filtrado de cultura em meio líquido e Agro-MOS®, produto comercial formulado a partir da levedura, além da testemunha com água destilada e do tratamento controle com fungicidas. Nenhuma das preparações apresentou efeito contra a mancha-de-micosferela; preparações com a presença de células vivas e o produto Agro-MOS® apresentaram efeito contra mancha-de-dendrofoma; preparações com suspensão do produto comercial e filtrado de cultura líquida reduziram a incidência de flor-preta em flores e frutos. Preparações de S. cerevisiae com suspensão de células, suspensão autoclavada de células e filtrado de cultura líquida promoveram aumento na produtividade dos morangueiros que variou de 589,6 a 617,8 g planta-1. Preparações de S. cerevisiae, com presença de células vivas ou não, alteraram o metabolismo do morangueiro, aumentando a atividade das enzimas quitinase e glucanase, envolvidas na resistência sistêmica adquirida. Todos os tratamentos, com exceção do tratamento com suspensão autoclavada de células, reduziram a incidência de mofo-cinzento em pós-colheita de frutos.

NEW APPROACHES TO SELECT CULTIVARS OF BANANA WITH DURABLE RESISTANCE TO MYCOSPHAERELLA LEAF SPOT DISEASES

ISHS III International Symposium on Banana: ISHS-ProMusa Symposium on Recent Advances in Banana Crop Protection for Sustainable Production and Improved Livelihoods NEW APPROACHES TO SELECT CULTIVARS OF BANANA WITH DURABLE RESISTANCE TO MYCOSPHAERELLA LEAF SPOT DISEASES

Epicuticular waxes and plant primary metabolites on the surfaces of juvenile Eucalyptus globulus and E. nitens (Myrtaceae) leaves

Our knowledge of the composition of the waxes on the surfaces of Eucalyptus leaves is growing but that of plant primary metabolites has been completely overlooked. The diffusion of primary metabolites above the cuticle exposes them to a variety of herbivorous taxa and has the potential to influence their responses to that plant. Juvenile leaves of two families of Eucalyptus globulus Labill. ssp. globulus and two families of E. nitens (Deane & Maiden) Maiden had 11 out of 16 of the epicuticular waxes that were detected in common. However, two phenylethyl esters (waxes) were only detected on leaves of one family of E. globulus and two benzyl esters (waxes) were not detected or were uncommon in samples from E. nitens. Wax compounds were generally found in samples from both leaf surfaces but a few were only detected in samples from particular sides. Species and families of eucalypt did not differ significantly in the concentrations of free sugars, polyols, malic acid or γ-aminobutyric acid (GABA) (all plant primary metabolites) collected from the surfaces of leaves. However, concentrations of all these metabolites were usually higher in collections from the upper surfaces of leaves. High wax abundance, especially on the lower surfaces of E. globulus leaves, is suspected to have hindered dissolution of all the primary metabolites quantified. Several free amino acids exhibited significant species-level differences in concentrations, namely the aromatic, amide and sulfur-containing amino acids as well as proline; family-level differences in amino acid concentrations were not significant. Australian and overseas evidence showing that differences in waxes and primary metabolites can be influential in plant susceptibility to herbivorous taxa is considered with respect to the threats posed by the autumn gum moth and Mycosphaerella leaf spot fungi.

Nematode resistance in bananas: screening results on some new Mycosphaerella resistant banana hybrids

Banana hybrids with resistance to Yellow Sigatoka and Black Leaf Streak disease were evaluated for resistance to the burrowing nematode Radopholus similis and to the lesion nematode Pratylenchus coffeae in a growth chamber at 24–28°. Plants produced by tissue culture were acclimatised for 6 weeks prior to inoculation. Forty-five days after inoculation with nematodes, the root systems were processed and nematode numbers assessed. Two cultivars of Grande Naine (Musa AAA, Cavendish subgroup, ITC1256 and cv902) and one cultivar of Yangambi Km5 (Musa AAA, Ibota subgroup, ITC1123) were used respectively as susceptible and resistant controls. Results based on multiplication rates and root infestations showed that three of these hybrids (FB918, FB919 and FB924) were not significantly different from the resistant control Yangambi Km5 with a lower multiplication of R. similis. Similarly four of these hybrids (FB918, FB919, FB920, FB924) showed a lower multiplication of P. coffeae, not significantly different from the same resistant control. This is the first study that shows a partial resistance to both nematode species, R. similis and P. coffeae within synthetic hybrids of M. acuminata, adding an important extra value to these dessert banana hybrids formerly bred to resist to Mycosphaerella leaf spot diseases.

Época de aplicação de fungicida para controle da mancha de Mycosphaerella do morangueiro

Estudou-se o efeito da época do início da aplicação de fungicida na severidade da mancha de Mycosphaerella fragariae em parcelas experimentais de morango cv. IAC-Campinas. O ensaio foi conduzido em área produtora (Brazlândia, DF) em blocos ao acaso com seis tratamentos (épocas de início de pulverização) e quatro repetições. Foram efetuadas aplicações quinzenais com o p.a. prochloraz (450 g i.a/litro) na dosagem de 100 ml/100 litros de água, e testadas as épocas de início de aplicação: Plantio (pulverização por ocasião do plantio das mudas, com um total de dez aplicações); Flor1 (após a primeira florada, oito aplicações); Flor2 (após a segunda florada, seis aplicações); Flor3 (após a terceira florada, quatro aplicações); Flor4 (após a quarta florada, duas aplicações) e Test (testemunha pulverizada com água desde o transplantio). As seguintes variáveis foram avaliadas: produção total acumulada; severidade de doença; número de folhas mortas e sadias; número de hastes lesionadas e sadias. Os resultados indicaram que os tratamentos Plantio e Flor1 foram superiores aos demais em todos os critérios (Duncan, 5%). O tratamento Flor2 apresentou controle intermediário de doença. Os demais tratamentos não apresentaram diferenças estatísticas significativas entre si.

New species of Mycosphaerella occurring on Eucalyptus leaves in Indonesia and Africa

Although Africa and Indonesia have not been particularly well surveyed for Mycosphaerella leaf spot fungi, several species are known to occur on Eucalyptus leaves in these areas. Three new species of Mycosphaerella with anamorph states are described from herbarium specimens and cultures in the present study. Mycosphaerella suttoniae and Mycosphaerella heimioides are described from Eucalyptus leaves from Indonesia. The former species is of particular interest, because its anamorph Phaeophleospora epicoccoides is the first species of Phaeophleospora linked to Mycosphaerella. Mycosphaerella irregulariramosa is described from Eucalyptus saligna growing in the Northern Province of South Africa. Both M. irregulariramosa and M. heimioides have Pseudocercospora anamorphs, and these are described as Pseudocercospora irregulariramosa and Pseudocercospora heimioides. Notes are also provided on the host range and geographic distribution of previously described species of Mycosphaerella on Eucalyptus leaves in other parts of Africa and in Indonesia. Key words: Eucalyptus, Kirramyces, Mycosphaerella, Phaeophleospora, Pseudocercospora, systematics.

Destruction ofGnomonia LeptostylaPerithecia onJuglans NigraLeaves by Microarthropods Associated withElaeagnus UmbellataLitter

Companion planting of the woody shrub autumn olive, Elaeagnus umbellata Thunb., with black walnut, Juglans nigra L., in plantations resulted in control of Mycosphaerella leaf spot (4, 5) and walnut anthracnose (3), important defoliating diseases of black walnut. One of the principal beneficial effects ofthe autumn olive was to reduce ascospore primary inoculum ofthe two disease causal agents, Mycosphaerella juglandis Kessler and Gnomonia leptostyla (Fr.) Ces. & de Not. in the spring. A major cause of the reduced ascospore production of M. juglandis and G. leptostyla was microarthropod feeding upon perithecia within infected fallen walnut leaves (4). The purpose of this study is (1) to describe the type and extent of microarthropod perithecial feeding occuning in the leaf litters and (2) investigate the possible role of Collembola and oribatid mites as probable main fungal feeders involved.

Effects of Mycosphaerella Leaf Spot on Growth of Eucalyptus nitens

Effects of Mycosphaerella Leaf Spot on Growth of Eucalyptus nitens