Main content area

Occlusion of sap flow in elm after artificial inoculation with Ophiostoma novo-ulmi

Urban, J., Dvořák, M.
Acta horticulturae 2013 no.991 pp. 301-306
Ceratocystis ulmi, Ophiostoma, Ulmus glabra, aggression, branches, clones, field experimentation, fungi, heat, monitoring, mycoses, sap flow, trees, Czech Republic
In a field experiment, the sap flow of four year old wych elm (Ulmus glabra) was measured in response to inoculation with Ophiostoma novo-ulmi, a causal agent which causes vascular mycosis called Dutch elm disease. Three trees were inoculated with three different strains of O. novo-ulmi and two other trees served as controls. Sap flow of those trees was measured by trunk heat balance method (EMS 62, Czech Republic) during the entire experiment. First measurable symptoms of sap flow reduction appeared five days after the inoculation and all inoculated branches were dead within sixteen days. Preliminary results also suggest different aggressiveness of various clones of the fungi. Our experiment confirmed ability of O. novo-ulmi to quickly kill young elm trees. Progress of the disease was faster than in previous experiments utilizing O. ulmi and, to our best knowledge, this is the first sap flow measurements on trees inoculated by O. novo-ulmi. Sap flow measurements by heat balance technique provided a non-invasive tool for continuous quantitative monitoring of progression of the vascular disease.