The Collaborative International Dictionary of English v.0.48:

Defoliate \De*fo"li*ate\, Defoliated \De*fo"li*a`ted\ a.
   Deprived of leaves, as by their natural fall.
   [1913 Webster]

WordNet (r) 3.0 (2006):

defoliated
    adj 1: deprived of leaves [syn: defoliate, defoliated]