I have several dying pines. I'm sampling for nematodes, but wonder what the other possibilities are. This tree looks worst. Small galleries, sawdust around base. The sample I took for nematodes does have blue staining starting on the inside.
Boulder County Colorado trees and shrubs
I'm sending you links to several facts sheets related to your pine tree. One is pine wilt disease caused by nematodes. I don't know what species you have but this may be helpful.
- Exotic pines including Scots, Austrian, and mugo are susceptible to infection by the nematode. Native pines are not susceptible to this pathogen.
The only certain way to diagnose pine wilt is to submit a wood sample to a diagnostic lab for extraction and confirmation of the presence of PWN. Diagnosticians usually require for analysis a one inch (2.5 cm) thick sample of wood from the trunk (pie slice, wafer, etc.) or a wilted branch that is 6 inches (15 cm) long and 2-3 inches (5-7.5 cm) in diameter taken nearest the trunk. Because the distribution of the PWN in a tree can be non-uniform, it is best to collect at least two samples from different parts of the tree.
- Looking at your pictures you may have an IPS beetle infestation http://extension.colostate.edu/topic-areas/insects/ips-beetles-5-558/
- Boulder County Master Gardner office