Evaluation of Vinca Cultivars for the Landscape or as Potted Plants In Guam

Forty-nine vinca (Catharanthus roseus) cultivars were evaluated for days to flower, flower diameter, flower color, plant dimensions, general tolerance to disease and appearance during the drier months in Guam. While vinca can be a perennial in Guam's growing conditions, the majority of cultivars succumb to target leaf spot (Corynespora cassilcola) once rainfall increases. Mediterranean cultivars were found to be highly susceptible to target leaf spot. Plants were grown in soil in raised beds and in pots on raised beds. In general, the cultivars survived longer in pots than in ground beds.