Effects of Rose Cultivars and Fertilization Rates on Populations of Scirtothrips dorsalis (Thysanoptera: Thripidae) in Southern Florida

Roses (Rosa spp. L.) are important ornamental hosts of chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae). The knowledge of how these thrips affect 8 cultivars of landscape roses popular in Florida (‘Angel Face’, ‘Don Juan’, ‘Pink Summer Snow’, ‘Radeon’, ‘Radrazz’, ‘Radsunny’, ‘St. Patrick’, and ‘Sun Flare’) would help in developing techniques for integrated pest management of S. dorsalis. The effects of 3 rates of fertilizer and cultivars on population densities of chilli thrips and on host plant damage were evaluated. Fertilization rate, plant organ, and cultivar were important in determining S. dorsalis population density. Differences in total numbers of S. dorsalis, damage rating, and in numbers of flowers and buds produced were observed among different fertilizer rates. The higher rates recommended for accelerated floral growth resulted in more S. dorsalis damage, but not in more flowers than the rates suggested for maintenance. Among parts of the rose plant, buds had the highest density of S. dorsalis, followed by flowers and leaves, which had similar low densities. Larger flowers had more S. dorsalis than small flowers, but population densities were similar. Different cultivars of Knock-Out® rose were similar in their susceptibility to S. dorsalis, but ‘Radeon’, ‘Don Juan’, and ‘Sun Flare’ had more damage with lower S. dorsalis abundance and density than other the cultivars.