Ethylene production and premature senescence of needles from fir trees (Abies alba)

Measurements of ethylene production, free and conjugated ACC concentrations, chlorophyll content, and length of needles from fir trees (Abies alba Mill.) growing in stands affected by “Waldsterben” showed that during the development of the disease two consecutive stages can be distinguished: a. long-term, low ethylene production and accumulation of conjugated ACC (MACC) in response to chronic stress, associated with reduced needle growth, and b. high ethylene production associated with chlorophyll breakdown, followed by premature abscission of the needles.