Electrical resistance measurements to detect Dutch elm disease prior to symptom expression

Abstract

Greenhouse-grown elm seedlings inoculated with Ceratocystisulmi developed visible symptoms of Dutch elm disease within 14 to 23 days. Mean electrical resistance measurements were used to detect alterations within host xylem tissue up to 6 days prior to symptom expression in populations of trees. Criteria are given for prediction of the disease in individual trees from 2 to 12 days prior to symptom expression.