Measurement of Gas Exchange in Woody Plants

Abstract

METHODS of controlling Dutch elm disease have been investigated at this laboratory for the past four years. Emphasis has been placed on two approaches to the problem of control. One approach has been the search for a suitable chemotherapeutant to control the causal agent, the fungus Ceratocystis ulmi (Buism) C. Moreau. The other approach has been the screening of systemic insecticides to control its vectors, the European elm bark beetle, Scolytus multistriatus (Marsham), and the native elm bark beetle, Hylurgopinus rufipes (Eich). A difficulty was found in methods of measuring the effects of chemotherapeutants and pesticides on diseased and healthy American elms, Ulmus americana L., in the laboratory under controlled conditions. A careful survey of existing literature showed that no device existed for measuring the effects of chemotherapeutants, pesticides and disease. Indeed, other workers in these fields have expressed and emphasized the lack of methods of measuring disease in woody plants1,2. This led us to investigate respiration as a means of studying the effects of chemotherapeutants and pesticides on woody plants.