Calibrachoa (Solanaceae) is a plant genus typical of open environments that occurs in both the Pampas and the high-altitude grasslands of southern Brazil (Fregonezi et al. 2012). Calibrachoas (mini petunias) are hybrids developed from native germplasm, with increasing importance in the ornamental plant market. During October 2019, basal rot was observed in plants of C. hybrida cv. INTA 06575 grown in a propagation greenhouse in Hurlingham, Buenos Aires. Those symptoms caused the darkening and withering of the leaves (incidence of 10 %). White mycelial mats containing sclerotia of 2 to 8 mm in diameter were evident on the base of the wilted plants and the nearby soil surface. Pieces of symptomatic stem tissues were surface-disinfested in ethanol 70% for 1 min, sodium hypochlorite (2 g Cl/L) for 1 min, washed with distilled water for 1 min, and placed on potato dextrose agar (PDA) plates. The plates were incubated in the dark for 5 days at 23°C and individual colonies were transferred to new plates of PDA to obtain pure cultures. The colonies developed white cottony mycelium, and a ring of large black sclerotia at the periphery of the plates. No teleomorph was observed. Based on the morphology of the colony, sclerotia, and microscopic observations, the pathogen was identified as Sclerotinia sclerotiorum (Lib.) de Bary (Mordue and Holliday 1976). A representative isolate was deposited in the Entomopathogenic Fungal Culture Collection of Argentina, CEPAVE as CEP 785. Genomic DNA was extracted and the internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 (White et al. 1990). The resulting sequence was deposited in GenBank (Accession No. MT177216) and the BLASTn search showed 100 % of identity with those of S. sclerotiorum (ex. MG931017, KX781301). The pathogenicity of the isolate was confirmed by placing plugs of 10 mm2 obtained from a 7-day-old culture grown on PDA,on the stem bases of 12 healthy potted calibrachoas 2 months old. Those segments were wrapped with moistened sterilized cotton (Choi et al. 2017). Four plants with sterile PDA plugs served as controls. Each plant was placed inside a polyethylene bag, and all of them were kept in a growth chamber at 20°C. All the inoculated plants had their leaves discolored after five days, and wilted after thirteen days. Sclerotinia sclerotiorum was consistently re-isolated from rotten stem bases, thus fulfilling Koch’s postulates. Control plants did not develop symptoms. To our knowledge, this is the first report of S. sclerotiorum causing basal rot on Calibrachoa hybrida (Farr and Rossman 2020) in Argentina, and in the world.

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) P 20 :M 25 :Pe 40 :Z 15; 2) PL 85 :Z 15; 3) P 20 :M 25 :Pe 30 :Z 15 :T 10; y 4) PL 75 :Z 15: T 10 . Se confeccionaron tres mesadas divididas en cuatro unidades experimentales de 1,2 m 2 . 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 (cm 2 ) 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 PL 75 :Z 15 T 10, y por S. alba en los sustratos P 20 :M 25 :Pe 40 :Z 15 y PL 75 :Z 15 T 10 . Sedum mexicanum cubrió menor superficie en el sustrato PL 85 :Z 15 , 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.

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.

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.