Question
We have a stand of ponderosa pine, that has been dying, we have just cut 10-15 trees in the past month, the trees are located in our horse pasture, where the  horses are fed and the manure build-up is quite high. I am wondering if that would have some affect on why we have so many of these trees dying, also here in northwest Montana we have a beetle issue also, so I am wondering maybe that could be the problem. Thanks for your help, I will look forward to hearing back from you, Doug  

Answer
Sounds like the trees are under stress from the horses either by compaction of the soil or the increase in urea and nitrogen form the manure. The stressed pines are an easy target for pine mountain beetle attack. I would suggest that you call the Montana Forestry Agency and ask one of their Forester to come take a look. Here is the web link to tier contact page.

http://dnrc.mt.gov/forestry/Assistance/Servicemap.asp

The signs of beetle infested trees are wads of pitch on the bark , boring dust on the bark, or all the needlesturning from green to brown or red. Here is a web link to more information on pine mountain beetles in Montana.

http://beetles.mt.gov/