Zelkova: A 20-Year History in Southern Michigan

Abstract

In 1955, 102 Zelkova serrata trees were planted on the grounds of the Agricultural Experiment Station at Michigan State University at East Lansing. During the next 10 years, 23 trees died of unknown causes. Beginning in 1966, the condition of each tree was determined annually. By 1975 an additional 38 trees had died, primarily from nectria canker (Nectria cinnabarina) or mouse injury. Death from canker could not be correlated with the frequent injury the trees received from lawnmowers but once a tree became colonized by canker, it usually died. Of the 41 trees alive in 1975, 25 had good or satisfactory crown shape while 16 had distinctly lopsided crowns. None of the 41 trees had active trunk cankers but 6 trees had. at least one active canker on a main branch. Eight trees had severe V-crotches where the trunk divided into the crown. The trees had an average diameter one meter above ground line of 16 cm; the largest being 27 cm. In spite of the rather high mortality of these trees, Zelkova appears to be a suitable shade tree if care is taken in site selection and maintenance.