Christmas tree pests and weeds Douglas fir, grand fir, white fir and California red fir on Christmas trees in Santa Clara County. Camellias imported from California to British Columbia in 2003 and early 2004 caused a significant SOD scare in the horticultural and Christmas tree industries. The detection of "P. ramorum" led to plant recalls in Canada, and a series of steps meant to quarantine the disease before it spread. The 2003–2004 SOD scare extended to Washington and Oregon nurseries and farms. Douglas-firs are vulnerable to the two plant pathogens that cause Rhabdocline needlecast, "Rhabdocline pseudotsugae", and "Rhabdocline weirii". "R. weirii" affects only Douglas-fir trees.
WAVL tree red–black tree, because they would in effect cause the recoloring of large subtrees of the red–black tree rather than making color changes only on a single path in the tree. This allows WAVL trees to perform fewer tree rotations per deletion, in the worst case, than red-black trees. WAVL tree In computer science, a WAVL tree or weak AVL tree is a self-balancing binary search tree. WAVL trees are named after AVL trees, another type of balanced search tree, and are closely related both to AVL trees and red–black trees, which all fall into a common framework of rank balanced