Resumen. La cenicilla del rosal causada por Podosphaera pannosa afecta todas las partes aéreas de la planta, lo que repercute en su calidad como principal componente de la pérdida económica. En el presente trabajo, se confirmó la identidad del agente causal de la cenicilla en rosa y se evaluó el efecto del fosfito de potasio (K 3 PO 3 ), silicio, quitosano y acetato de dodemorf sobre la incidencia y severidad de la enfermedad, así como, su respuesta en la calidad de tallos florales. Se realizaron dos ensayos (febrero-abril y mayo-julio). Las caracterís-ticas morfométricas y moleculares del agente causal de la cenicilla correspondieron a Podosphaera pannosa. El K 3 PO 3 , silicio y quitosano redujeron Abstract. Rose powdery mildew caused byPodosphaera pannosa affects all aerial parts of the plant, which affects their quality as a major component of economic loss. In this work, the causal agent of powdery mildew of rose was identity and confirmed, the effect of potassium phosphite (K 3 PO 3 ), silicon, chitosan and dodemorph acetate on the incidence and severity of the disease was evaluated, as well as their response in the quality of flower stalks. Two trials (February to April and from May to July) were performed. The morphometric and molecular characteristics of the causal agent corresponded to Podosphaera pannosa. The K 3 PO 3 , silicon and chitosan they reduced incidence and severity compared to the control for both assays, however, only the K 3 PO 3 and silicon, exhibited a control similar to provided by the fungicide dodemorph acetate. The treatment with chitosan increased the length and diameter of the stem and flower bud in contrast to K 3 PO 3 and silicon, but was not significant to the control in both tests. Based on the results, the K 3 PO 3 , silicon and