Currently in vitro plantlets and microtubers provide the basis for pre-base production of potato seeds, from which minitubers are produced under covers -they serve later as seed material to be planted in the field. The aim of the research was to determine the possibility for multiplication of material produced in vitro directly in field conditions. The research assessed PVY, PVM and PLRV infection of potato tubers derived from plants grown directly from in vitro plantlets, microtubers, minitubers and traditional seed potatoes planted in the field at different times. Moreover, testing in laboratory conditions, the susceptibility of these plants to virus infection was determined for the case of artificial inoculation of Myzus persicae and Aphis nasturtii. It was found that the infection of tubers derived from in vitro plantlets and microtubers was greater than that of seed potatoes and minitubers. Yet it seems that the reason for their higher infection level resulted not from the plant's sensitivity or its greater attractiveness to aphids but from a largely unknown cause. Earlier planting of microtubers and in vitro plantlets in the field in case of the more resistant cultivar and certainly later in relation to the main time of planting had an impact on limiting the PVY and PVM infection of potato tubers. Hence multiplication of microtubers and in vitro plantlets in field conditions could be very economical using cultivars which are relatively resistant to viruses. However, adopting a later than usual planting period (end of June) and applying an additional protective cover (such as non-woven agricultural fabric) in the first period of a plant's growth, promotes multiplication of microtubers and in vitro plantlets in field conditions for cultivars with low resistance levels.Resumen Actualmente, las plántulas in vitro y los microtubérculos suministran el sustento para la producción de semillas pre-básicas de papa, de las cuales se producen los minitubérculos bajo cubierta, que después sirven como material de siembra para ser plantado en el campo. El propósito de esta investigación fue determinar la posibilidad para multiplicación de material producido in vitro directamente bajo condiciones de campo. La investigación analizó la infección por PVY, PVM, y PLRV en tubérculos derivados de plantas que crecieron directamente de plántulas in vitro, microtubérculos, minitubérculos y semilla-tubérculo tradicional de papas sembradas en el campo en diferentes tiempos. Además, en pruebas de laboratorio se determinó la susceptibilidad de estas plantas a la infección viral mediante inoculación artificial de Myzus persicae y Aphis nasturtii. Se encontró que la infección de tubérculos derivados de plántulas in vitro y microtubérculos era mayor que la del tubérculo-semilla y minitubérculos. Sin embargo, parece ser que la razón para su mayor nivel de infección fue el resultado, no de la susceptibilidad de la planta o por su mayor atractivo a los áfidos, sino por otra causa mayor desconocida. La siembra temprana de microtubér...