First report of Berkeleyomyces basicola (synonymous: Thielaviopsis basicola) on roots of sweet potato (Ipomoea batatas (L.) Lam) in Argentina

Symptomatic sweet potato cv Arapey INIA samples were collected from a commercial production field in Colonia Molina, Guaymallén department, Mendoza province, Argentina. They showed dark rounded lesions, sometimes coalescing with white granular mycelium. Fungus was obtained from symptomatic sweet potatoes, which represented the generalized infection that affected the crop. They were seeded in PDA with streptomycin sulfate and incubated for seven days at 21°C, alternating white/black (UV400nm) light. Observations with an optical microscope revealed the presence of hyaline, not septated, cylindrical endoconidia with rounded ends. They were 8-16 μm length and 4–6 μm width. Phialides were 43-46 μm length, rounded bases (7-9 μm width) and tapering to the neck´s tip (4-6 μm width). Brown chlamydospores (aleuriospores), 9-13 μm length and 8-12 μm width, in chains of 2-8 spores were observed. For molecular identification, total genomic DNA was extracted. ITS fragment of 565 pb was amplified using ITS5/ITS4 primers and sequenced. The sequence indicated 99% identity with Berkeleyomyces basicola (synonymous: Thielaviopsis basicola). This was deposited in GenBank as (KX580957) (CBS: C430.74, Gen Bank accession number AF275482.1). This is the first report of B. basicola in sweet potato in Argentina, a potential threat to storage root yields. Highlights: Sweet potato black root rot, new disease in Argentina. First report of Berkeleyomyces basicola causing black root rot on sweet potato in Mendoza, Argentina.

A New RoVe Method to Purify Endophytic Fungi from Medicinal Plants Western Ghats of Karnataka India

Endophytic fungi from medicinal plants were hardly ever reported as compared to those from soil and marine sources. The present results associate the presence of endophytic fungi in medicinal plants by isolating them from three medicinal plants i.e. Bombax ceiba, Aloe vera, and Ximenia americana. In the present research investigation, surface sterilization method and media were standardized, and 32 endophytic fungi were isolated from three medicinal plants. We assessed the competence of three different surface sterilization methods and four media for isolation of endophytic fungi. The RoVe method used was more effective in eliminating epiphytic microorganisms. Therefore by using new method we have isolated total of 32 fungal endophytes and those were belongs to Aspergillus nomius (63.20%), Aspergillus niger (41.60%), Thielaviopsis basicola (38.33%), Fusarium oxysporum (33.20%), Pestalotiopsis inflexa (27.20%), Nigrospora sphaerica (20%), Alternaria alternata (15.30%) and Phomopsis archeri (20%). This is the first report of successful isolation of endophytic fungi from the said medicinal plants, for using newly formulated surface sterilization method.

Atividade antifúngica in vitro dos óleos essenciais Eugenia uniflora e Psidium cattleianum contra o fitopatógeno Thielaviopsis basicola.

O fungo Thielaviopsis basicola (Berk. & Br.) Ferr é responsável por grandes perdas econômicas em diversas culturas agrícolas. O uso de óleos essenciais é uma técnica de controle alternativo de doenças fitopatogênicas. Este trabalho teve por objetivo caracterizar os compostos bioquímicos de óleos essenciais extraídos de folhas de Eugenia uniflora L (Pitanga) e Psidium cattleianum ‘Sabine (Araçá Vermelho) e avaliar se concentrações crescentes desses óleos essenciais aumentam a inibição do crescimento do fitopatógeno T. basicola. A caracterização dos compostos bioquímicos ocorreu pela análise em GC/MS em cromatógrafo gasoso. Para o teste in vitro foram utilizadas concentrações de 0,1%, 1,0% e 1,5% de cada óleo essencial extraído, sendo este diluído em meio BDA mantendo-se um tratamento controle (ausência dos óleos essenciais). Utilizou-se delineamento inteiramente casualizado, com cinco repetições. As placas foram incubadas por 19 dias à 25°C. As avaliações foram realizadas através de medições dos diâmetros das colônias. Verificou-se inibição de crescimento do fungo nas concentrações de 1,0% e 1,5% para ambos os óleos testados. Os resultados obtidos neste estudo demonstram que shiobunona e espatulenol são os compostos bioquímicos com maiores concetrações em óleo essencial de folhas de E. uniflora, enquanto 1.8-cineol é o composto bioquímico com maior concetração em óleo essencial de folhas de P. cattleianum. Ainda, os resultados obtidos confirmam a eficácia dos óleos essenciais no controle do crescimento de T. basicola, onde concentrações crescente desses óleos essenciais aumentam a inibição do crescimento desse fungo.

Prevalence of Soil-borne Diseases in Kalanchoe blossfeldiana Reveals a Complex of Pathogenic and Opportunistic Fungi

Greenhouse cultivation of ornamentals is subjected to a high incidence of soil-borne fungal pathogens. In Kalanchoe, these pathogens are responsible for root and stem rot, and for infection of the vascular tissue. Well-known soil-borne pathogens are believed to cause these diseases. Yet, a systematized survey of these pathogens is lacking for Kalanchoe produced commercially. Here, we studied the occurrence of soil-borne fungal pathogens associated with cultivation of Kalanchoe in Denmark and production of cuttings and stock plants in greenhouse facilities located in Turkey and Vietnam. Molecular identification of pathogens complemented mycological identification and pathogenicity testing of the soil-borne fungal pathogens. This study revealed that the fungi Corynespora cassiicola, Thielaviopsis basicola, Fusarium solani, and F. oxysporum are the most prevalent pathogens associated with root and stem rotting and wilt of Kalanchoe under the conditions studied. Furthermore, the study showed that some of the pathogens are part of an infection complex comprising both primary and opportunistic fungal species. The fact that some of the pathogens were present in some regions, while absent in others, suggests how they move between greenhouse facilities on infected plant material. This study generated important information about the soil-borne fungal complex affecting Kalanchoe, which is useful for a better understanding of the biology of the disease and for designing control strategies.

Évaluation de maladies racinaires du soya dans des champs de la Montérégie en 2014 et 2015

Un inventaire des maladies racinaires du soya causées par des champignons et des oomycètes a été réalisé en 2014 et 2015 dans 80 champs situés en Montérégie et 4 au Centre-du-Québec. Douze plantules au stade de deux feuilles trifoliées ont été prélevées par champ pour évaluer l’état sanitaire de leurs racines (indice racinaire) selon une échelle de 1 à 5 (1 = belles racines abondantes ; 5 = nécroses et peu de racines), et pour révéler dans ces racines, à l’aide de techniques de mise en culture, la présence de champignons et d’oomycètes pathogènes. L’indice racinaire moyen pour l’ensemble des champs était de 2,6 en 2014 et 3,2 en 2015. Des espèces de Pythium et de Fusarium étaient présentes dans presque 100 % des champs chaque année, alors que Rhizoctonia solani et Thielaviopsis basicola ont été plus abondants en 2015 (88 % des champs) qu’en 2014 (52 %). Phytophthora sojae n’a été isolé d’aucune racine, mais l’a été à partir des sols de 37 % des champs. Les espèces de Fusarium les plus fréquentes étaient F. solani, F. oxysporum et F. equiseti, présentes dans au moins 60 % des champs. La méthode d’analyse « stepwise » a sélectionné trois facteurs pour expliquer la variation de l’indice racinaire, dont deux ont montré des différences significatives entre leurs niveaux, soit le type de semence (indice plus élevé pour non-OGM que pour OGM) et le nombre d’années en culture de soya au cours des quatre dernières années (indice augmentant avec le nombre d’années). Le travail du sol a été le seul facteur sélectionné pour expliquer la variation des Fusarium totaux (somme diminuant avec l’intensité du travail de sol).