The Collaborative International Dictionary of English v.0.48:

Disbud \Dis*bud"\, v. t. [See Bud, v.] (Hort.)
   To deprive of buds or shoots, as for training, or economizing
   the vital strength of a tree.
   [1913 Webster]

WordNet (r) 3.0 (2006):

disbud
    v 1: thin out buds to improve the quality of the remaining
         flowers
    2: destroy undeveloped horn buds (of cattle)