"Net blotch" (Drechslera teres) and "Bipolaris spot blotch" (Bipolaris sorokiniana) are foliar diseases of barley. Biological control is currently considered as an efficient alternative to chemical management of these plant diseases. The aim of the present study was to identify 2 isolates of Chaetomium (C2 and C5), endophytics on barley seedlings and to study the in vitro interactions with D. teres and B. sorokiniana, isolated from seeds of the same host. Cultural and morphological characterization of all microorganisms was done. In addition, molecular characterization of Chaetomium spp. was conducted and dual culture tests were carried out to find, by microscopic observations, the effects of the antagonist on the morphology of the pathogens. The results confirm the identity of the pathogens and the isolates of Chaetomium spp. as Chaetomium globosum species group. Inhibition of B. sorokiniana and D. teres by C2 and C5 accounted for 30% and 31.2 %, and 40% and 36% respectively, compared with the control. The mechanisms of action against B. sorokiniana and D. teres were antibiosis and competition and mycoparasitism, respectively. Microscopic observation revealed deformed conidia in B. sorokiniana and plasmolisis, coiling and orange pigmentation in D. teres.

La "mancha en red y la "mancha borrosa" son enfermedades foliares de cebada causadas por Drechslera teres y Bipolaris sorokiniana, respectivamente. Una alternativa para su manejo es el control biológico. El objetivo de este trabajo fue identificar dos aislamientos del género Chaetomium (C2 y C5), endofíticos de plántulas de cebada y estudiar sus interacciónes in vitro con D. teres y B. sorokiniana, aisladas de semillas del mismo hospedante. Todos los microorganismos se caracterizaron cultural y morfológicamente. Los aislamientos de Chaetomium además se caracterizaron molecularmente. Se realizaron pruebas de cultivos duales y se registraron los efectos del antagonista a nivel microscópico en la morfología de los patógenos. Los resultados confirmaron la identidad de los patógenos y de los aislamientos de Chaetomium spp. como Chaetomium globosum grupo de especies. Bipolaris sorokiniana fue inhibida en un 30% por C2 y en un 31.2 % por C5 respecto al control. D.teres fue inhibida en un 40% por C2 y en un 36% por C5 en referencia al control. Los mecanismos de acción frente a B. sorokiniana fueron antibiosis y competencia. Microscopicamente se observaron conidios aberrantes. Frente a D. teres se registró competencia y micoparasitismo. Microscópicamente se evidenció plasmólisis, enrollamiento y pigmentación anaranjada.

O grão de arroz é, com frequência, atacado por uma série de patógenos (fungos) durante o armazenamento produzindo danos econômicos e à saúde humana. O objetivo do trabalho foi identificar os gêneros fúngicos presentes em diferentes genótipos de arroz e quantificar sua variação durante o armazenamento. Analisaram-se as frações casca, integral e polido dos genótipos Nutriar (N), H329-5 (H329) e Don Ignácio aos 4, 8 e 12 meses de armazenamento. Os fungos foram identificados por suas características micromorfológicas e suas colônias. Os gêneros observados segundo sua frequência foram: Alternaria, Nigrospora, Epicoccum, Bipolaris, Curvularia, Cladosporium e Fusarium (fungos de campo) e Penicillium e Aspergillus (fungos de armazenamento). A composição da micoflora foi diferente segundo fração de grão e tempo de armazenamento: os fungos de campo localizaram-se na casca e no farelo, enquanto os de armazenamento, no endosperma. Os diferentes genótipos apresentaram diferente suscetibilidade à contaminação.

The rice grain is frequently infected by a series of pathogens (fungi) during its storage, producing damages to the economy and health of humans. The aim of this study was to identify the fungal genera present in different rice genotypes and to quantify their variation during storage. Paddy, brown and milled rice fractions of Nutriar, (N) H329-5(H329) and Don Ignacio genotypes were analyzed at 4, 8 and 12 months of storage. Fungi were identified based on their micromorphological characteristics and colonies. The observed genera according to their frequency were: Alternaria, Nigrospora, Epicoccum, Bipolaris, Curvularia, Cladosporium and Fusarium (field fungi) and Penicillium and Aspergillus (storage fungi). The mycobiota composition was different depending on the grain fraction and the period of storage: field fungi were located in the hulls and bran layers, while storage fungi were mainly in the endosperm. The different genotypes showed different susceptibility to contamination.

For the first time, the genus Marielliottia is registered on wheat grains in Argentina. This fungus was isolated from seed samples from trials conducted at the Estación Experimental Julio Hirschhorn (Los Hornos, Buenos Aires). The seeds were plated on potato dextrose agar (PDA) and incubated at 21±1°C; HR 80% under fluorescent lamps supplemented with UV light during 12 h photoperiod. Evaluation was performed for the presence of fungi at 5 and 8 days with the aid of a stereoscopic microscope. For taxonomic identification, the micromorphology and cultures features were examined. As a result of this study, Marielliottia biseptata was determined and inoculations with spore suspension on seeds were carried out. A description, illustrations, antecedents and importance of the treated fungus are presented.

Se registra por primera vez al género Marielliottia asociado a la micoflora del grano de trigo pan en Argentina. Marielliottia biseptata fue aislada de muestras de semillas provenientes de ensayos conducidos en la Estación Experimental Julio Hirschhorn (Los Hornos, Buenos Aires). Las semillas fueron sembradas en agar papa glucosado (APG) e incubadas a 21± 1°C ; HR 80% bajo 12 h luz + UV; 12 h de oscuridad. La evaluación para el relevamiento de los hongos se realizó a los 5 y 8 días mediante una lupa estereoscópica. Para la identificación taxonómica, se examinaron las características micromorfológicas y de cultivo. Se realizaron inoculaciones sobre semillas con suspensión de esporas. Se presenta una descripción, ilustraciones, antecedentes e importancia del hongo aquí tratado.