ABSTRACT Calibrachoa (Calibrachoa hybrida, Solanaceae) is an annual flowering ornamental plant, which is widely used in landscape design. In October 2019, 5% of the plants grown in a greenhouse in Buenos Aires, Argentina, showed a sudden wilt characterized by chlorosis, loss of turgor, and root rot. The objective of this study was to identify the causal agent of the disease. Five morphologically identical isolates developed from the roots of wilting plants. One of the isolates was selected and identified using morphological and molecular markers, while its pathogenicity was confirmed by Koch’s postulates. The obtained results allow concluding that Ceratobasidium sp. AG-A (anamorph Rhizoctonia sp.) is the causal agent of the disease. To the best of the authors’ knowledge, this is the first report of Ceratobasidium sp. as pathogen of calibrachoa in the world.

ABSTRACT Extensive green roofs (EGR) contain less than 15 cm of substrate, which must be stable, with low density, high aeration and sufficient water and nutrient retention for adequate plant development. In search of alternative components to formulate this type of substrates, the objective of this work was to evaluate substrates with brick dust and its effect on the growth of species of the genus Sedum L. The trial consisted of four treatments/substrates composed of pumice stone (P), microleca (M), perlite (Pe), Sphagnum peat (T), enriched zeolite (Z) and brick dust (PL) in volumes indicated by the subscripts: 1) P20: M25: Pe40: Z15; 2) PL85: Z15; 3) P20: M25: Pe30: Z15: T10; and 4) PL75:Z15:T10. Three tables were made and divided into four experimental units of 1.2 m2. The Sedum species evaluated were S. acre, S. alba, S. mexicanum and S. ruflexum. Physical and chemical analyzes were carried out on all substrates. The surface area (cm2) covered by the vegetative part and survival was measured for each plant. All substrates had a pH value greater than 6.3 and a high initial electrical conductivity value, but low at the end of the trial. The aeration porosity in all substrates was greater than the water retention capacity. The surface covered by S. acre was greater in the substrate PL75: Z15T10 and by S. alba in the substrates P20: M25: Pe40: Z15 and PL75: Z15T10. Sedum mexicanum covered less surface in the substrate PL85:Z15, and no differences were observed with S. reflexum (P: 0.6114). Brick dust is a viable alternative for use in EGR.

RESUMEN Los techos verdes extensivos (TVE) contienen menos de 15 cm de sustrato, el cual debe ser estable, con baja densidad, alta aireación y suficiente retención de agua y nutrientes para el adecuado desarrollo vegetal. En busca de componentes alternativos para formular este tipo de sustratos, el objetivo de este trabajo fue evaluar sustratos con polvo de ladrillo y su efecto sobre el crecimiento de especies del género Sedum L. El ensayo fue conformado por cuatro tratamiento/sustratos compuestos por piedra pómez (P), microleca (M), perlita (Pe), turba de Sphagnum (T), zeolita enriquecida (Z) y polvo de ladrillo (PL) en volúmenes indicados por los subíndices: 1) P20:M25:Pe40:Z15; 2) PL85:Z15; 3) P20:M25:Pe30:Z15:T10; y 4) PL75:Z15:T10. Se confeccionaron tres mesadas divididas en cuatro unidades experimentales de 1,2 m2 . Las especies del género Sedum evaluadas fueron S. acre, S. alba, S. mexicanum y S. ruflexum. Se realizó análisis físicos y químicos a todos los sustratos. A cada planta se midió la superficie (cm2) cubierta por la parte vegetativa y la supervivencia. Todos los sustratos tuvieron un valor de pH superior a 6,3 y un valor inicial de conductividad eléctrica alto, pero menor al final del ensayo. La porosidad y aireación en todos los sustratos fue mayor que la capacidad de retención de agua. La superficie cubierta por S. acre fue mayor en el sustrato PL75:Z15T10 y por S. alba en los sustratos P20:M25:Pe40:Z15 y PL75:Z15T10. Sedum mexicanum cubrió menor superficie en el sustrato PL85:Z15, y con S. reflexum no hubo diferencias significativas (P : 0,6114). El polvo de ladrillo se muestra como una alternativa viable para su uso en TVE.

Resumo Calibrachoa hybrida (calibrachoa ou falsa-petúnia) é uma planta ornamental com importância crescente no mercado devido a existência de inúmeras variedades que podem ser cultivadas em vasos, jardins e paisagismo. A característica marcante é sua floração abundante e de cores vibrantes. Em outubro de 2019, foi obtido um isolado de fungo em folhas basais de calibrachoa, com manchas foliares marrons e irregulares, em plantas cultivadas em Buenos Aires, Argentina. O objetivo do presente estudo foi identificar o agente causal das manchas foliares em calibrachoa para expandir o conhecimento sobre as doenças prevalentes nesta importante planta ornamental. O isolado foi identificado por meio de marcadores morfológicos e moleculares, bem como a sua patogenicidade foi comprovada por meio do postulado de Koch. O fungo foi identificado como Nigrospora oryzae, sendo que presente artigo, além de relatar a sua patogenicidade, parece ser o primeiro registro desta doença em calibrachoa no mundo.

Abstract Calibrachoa hybrida (calibrachoa, million bells) is a flowering ornamental with increasing importance due to the existence of many successful cultivars for growing indoors in containers and planting in the garden and landscape. The outstanding characteristic is a profuse flowering and intense colour. In October 2019, a fungal isolate was obtained from basal calibrachoa leaves with irregular brown leaf spots, in plants cultivated in Buenos Aires, Argentina. The aim of the present study was to identify the cause of the disease in this ornamental genus, to expand knowledge about prevalent pathologies. The isolate was identified using morphological and molecular markers, and the pathogenicity tests were fulfilled. This paper reports that Nigrospora oryzae is pathogenic to calibrachoa, which seems to be the first record of this leaf spot disease in the world.

Resumo Seemannia Regel pertence à família Gesnereacieae. É uma planta perene herbácea com flores coloridas e brilhantes que produz rizomas escamosas carnudas com gemas dormentes axilares. O objetivo deste estudo foi avaliar o efeito do volume do recipiente na produção e na qualidade dos rizomas. Foram utilizadas plantas de um híbrido selecionado de Seemnania. Três volumes de recipientes foram testados: v1 de 1 L, v2 de 1,5 L e v3 de 2 L. As plantas foram cultivadas nos recipientes seguindo o manejo convencional. Foram registrados a massa seca, a produção (número e peso de rizomas) e qualidade dos rizomas. Os rizomas foram classificados em quatro categorias de qualidade (A, B, C, D) de acordo com o comprimento, a largura e o número de escalas. Todos os dados foram analisados estatisticamente. A massa seca, o peso e o número do rizoma aumentaram à medida que o volume do recipiente aumentou. Para o recipiente v3 foram registrados os maiores valores para esses três parâmetros. Quanto maior o volume do recipiente, maior foi o desenvolvimento da massa vegetativa e consequentemente, o número e o peso dos rizomas foram maiores. Em relação à qualidade dos rizomas, para os tratamentos v1 e v3 foram registrados o maior número de rizomas A (o tamanho maior) em comparação ao tratamento v2. O conhecimento da qualidade do rizoma pode ser útil para os produtores, a fim de selecionar o melhor tamanho para uma boa produção. O tratamento v3 registrou o maior número de rizomas A, considerado de boa qualidade, pois possui o maior tamanho com mais escamas e portanto com mais propágulos.

Abstract Seemannia Regel belongs to the Gesnereacieae family. It is an herbaceous perennial plant with colorful and brilliant flowers that produces fleshy scaly rhizomes with axillary dormant buds. The objective of this study was to evaluate the effect of the volume of the container in the production and the quality of the rhizomes. Plants of a select hybrid of Seemnania were used. Three volume of container were tested: v1 of 1 L, v2 of 1,5 L and v3 of 2 L. Plants were cultivated in the containers following a conventional management. Dry matter, production (number and weight of rhizomes) and quality of the rhizomes were recorded. The rhizomes were classified into four qualities (A, B, C, D) according to the length and width, and the number of the scales. All data was subject to statistical analysis. Dry matter, weight and number of rhizomes increased as the volume of container increased. The v3 container recorded the highest values for these three parameters. Major volume of container, major was the development of vegetative mass and consequently the number and the weight of rhizomes were higher. In regard to the qualities of the rhizomes, v1 and v3 treatments had a better proportion of A rhizomes (the bigger size) compared to v2 treatment. The knowledge of the rhizome quality can be useful to the growers in order to select the best rhizome size for a good production. The v3 treatment recorded the highest number of A rhizomes, that we consider a good quality, because it has the bigger size with more scales and consequently more propagules.