Morphological Characteristics and Occurrence of Yellow Tuft on Zoysiagrass (Zoysia japonica) in Cultivation Fields

Abstract

Yellow tuft symptoms of a dense cluster on zoysiagrass (Zoysia japonica Steud.) occurred extensively at cultivated fields of zoysiagrass sods in Jangsung. The dense cluster of zoysiagrass showed significant morphological changes such as the tufts of shortening of internodes. The disease symptom was spread on a large scale throughout stolon nodes with multiple short leaves and it thrives in broom-like shaped clusters, exhibiting light green or yellow color on their leaves. The dense cluster of zoysiagrass had approximately 5.8 times more leaves on each node of its stolon then healthy zoysiagrass. Also, these zoysiagrass had poorly developed root and stolon caused by the tufts of a dense cluster of shoots. The dense cluster of zoysiagrass were collected for the putative causal agent incubation and upon close observation, it was found that the sporangia took the shape of a lemon, each sporangium was pointed at the end of its axis and was measured to be 60~96×42~51 μm. These findings were analogous to the mycological characteristics of sporangia formed by the pathogen Sclerophthora macrospora. The symptoms of yellow tuft were prevalent in spring and autumn. Therefore, this study aims to present fundamental data in relation to yellow tuft on zoysiagrass in Korea.