I am interested in documented cases where defoliation by European giypsy moth (Lymantria dispar dispar) has led to die-back of oak on larger area (preferrably Europe). There is an on-going debate whether weakened oak forests need help by combating mass infestations of gipsy moth to avoid complete defoliation. Often a combination of different stress factors with the relatively late defoliation by gipsy moth may lead to death of individual oaks the followong year because necessary resources to develop new leaves are depleted. Forest owners fear the loss of old oaks on larger scale in extreme years like 2018 and argue for combating caterpillars of gipsy moth which may also affect non-target organisms. But are these fears reasonable? How big is the impact of defoliation on oak or other tree species?

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