The Analysis of Favourable Mass Multiplication Conditions of Defoliator Lymantria Dispar in Beech Forests from Romania

In Romania, Lymantria dispar is a defoliator with a high injury potential that produces strong and frequentgradations in Querqus forests in mixture with beech. The research concerning Lymantria dispar infestation was carriedout by in brushes from Herculane Baths County, with gradations of the defoliator in numerical growth and eruptionphases. The statistical data were processed by using the Discriminative Analysis. It has put into evidence the influenceof stationed and brushes properties on the appearance and development of gradations. Strong infestations dominatebrushes with a reduced consistency (0.4 – 0.7) and included in larger age classes. In eruption phase, one evidences theextension tendency on the altitude of infestations (advancing towards the versant, strongly inclined) and in brushes witha larger participation of beech, situated in different age classes and middle-superior production classes, with a morevigorous vegetation stage.