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.
Tree automaton three statements are equivalent: Tree automaton A tree automaton is a type of state machine. Tree automata deal with tree structures, rather than the strings of more conventional state machines. The following article deals with branching tree automata, which correspond to regular languages of trees. As with classical automata, finite tree automata (FTA) can be either a deterministic automaton or not. According to how the automaton processes the input tree, finite tree automata can be of two types: (a) bottom up, (b) top down. This is an important issue, as although non-deterministic (ND) top-down and ND bottom-up tree automata are