ROOT DAMAGE AND WATER-STRESS - TREATMENTS AFFECTING THE EXPLOITATION OF THE BUDS OF COMMON ASH FRAXINUS-EXCELSIOR L, BY LARVAE OF THE ASH BUD MOTH PRAYS FRAXINELLA BJERK (LEP, YPONOMEUTIDAE)

Damage to the buds of the common ash (Fraxinus excelsior L.) by larvae of the ash bud moth Prays fraxinella Bjerk. was investigated in trees growing in the presence, or absence, of an adjacent ditch. The presen ce of a ditch was correlated with increased damage levels due to bud m oth. Saplings were used in an experiment to compare the effects of art ificial drought and root damage with those of ditches. Both root damag e and drought elicited analogous responses to those observed in trees growing near a ditch, being associated with elevated levels of bud mot h exploitation and reduced growth of shoots. There exists a documented link between ditches, root disturbance, and the dieback of hedgerow a sh trees in Great Britain; the response of P. fraxinella to environmen tal disturbances associated with dieback is hypothesised to be evidenc e of the possible role of moth damage as a causal factor in dieback.