I'm a little worried about a large white pine tree on my property. It has a white substance on the underside of many of the branches, up to a height of about 15 feet. It is white and fluffy like cotton. I don't know if it is a fungus, mold, or mildew of some sort. The tree has always seemed healthy. The most recent thing I've done to the tree was last year when I dug a large round mulch bed underneath it; so that when the pine leaves fall in autumn, they give a nice fresh layer of mulch. I also put some hostas under it for some decoration. I attached a picture so you can see what it looks like. After doing a bit of research, I think it may be the pine bark adelgid, but I'm not 100% sure of that either. If you could point me in the right organic direction for treating this...I would appreciate it. I grow vegetables organically nearby, so I would not want to use chemical treatments that would adversely affect beneficial insect populations in any way. I've read about some spray oils that may help, but I'm not sure which of those to use or the best time of year to use them. The sprays that I've read about are the following:

1. R Chlorpyrifos E-Pro 4CSG; ESG; PB
2. R Chlorpyrifos Pro 2 CSG; ESG; PB
3. R Chlorpyrifos Pro 4CSG; ESG; PB 
4. R Dursban 50WCSG; ESG; PB

The initial "R" stands for "Restricted use", which worries me, that it might taint my organic methods.  I'm not sure of the definition of "restricted use" in this case.  I really hope the tree is not in any fatal danger, and I hope to treat it correctly, with your help. Thanks so much in advance. Ed Tomassetti