The Role of Xylem Vessel Size and Ray Traits in Dutch Elm Disease Frequency in Ulmaceae

Dutch elm disease is one of the most destructive and common plant vascular diseases now which is known as a global problem. The aim of this study was comparison of early- and late-wood vessels diameter and ray dimensions. In 4 species: Ulmus carpinifolia, Zelkova carpinifolia, Ulmus glabra and Celtis australis from Ulmaceae. Then, very thin transversal sections were prepared and after different stages of staining, microscopic slides were prepared. The data of xylem vessel and ray attributes measurement among disease and healthy species analysis via one-way at level of 0.01. The compare means was done with Duncan test. The results showed that the maximum and minimum frequency of disease belong to English elm and Hackberry respectively. There is significant difference between xylem vessels and ray attributes of species. The results of light and electron microscopy showed that there is a change and destruction in xylem vessels and ray structure in affected trees.