• Zimel, David Morris
  University of Maine Graduate School
  

Time of high susceptibility of American elm (Ulmus americana L.) to infection by the Dutch elm disease pathogen, Ceratocystis ulmi, coincident with low levels of energy reserves in June stimulated an evaluation of the possible role of such reserves in disease development. Little is known of the seasonal levels of energy reserves in American elm during this period of highest susceptibility to Dutch elm disease. Accordingly, a study was undertaken to explore the role of such reserves in elm as a potential factor in the development of Dutch elm disease. The objectives of this investigation were: (1) To determine quantitative levels of starch and extractable sugars in healthy elms and those affected by Dutch elm disease before, during, and after the period of highest susceptibility to infection, and, (2) To determine the types of extractable sugars present in the xylem during this period.