Thank you for getting back to me, Harold. The yellow substance is sap. It's oozing out from the trunk, and possibly the branches if they have the yellow substance, too. Leaking of sap can be the result of an injury, such as being scraped by a lawn mower. However, when the sap is seen is more than one place, something else is probably to blame.
This can be a first sign of pine bark beetles. The beetles tunnel inside the tree and damage it. Nutrients and water cannot pass properly to the needles, and they turn orange, yellow, or brown. If the needles have not started to turn, it is possible to save the tree. Spray the trunk with lindane (available at garden centers and nurseries).You can read more about the beetles here:http://www.barkbeetles.org/pbb/pbbpub.html
The other possibility is a bacterial or fungal canker. It won't hurt to use a fungicide, but to be honest, it probably won't help much. Once trees are infected, canker is hard to eliminate. It just has to be managed with regular pruning of dying branches and general good care.
If you can send photos of the tree, I may be able to tell you which condition is occurring. Or, you can examine the trunk carefully. The beetles leave small tunnels under the bark. Canker causes darkened spots that look wet. If you can spot either of these clues, you'll know what is wrong.
If you want to send pictures, you can upload a photo by clicking on REPLY, then at the top of the area where you would type is a tool bar with icons. Click on the little paper clip icon (it's right next to the YouTube icon). Instructions will pop up. On some browsers, this doesn't work. if that happens, you can put your photo on one of the free photo sharing websites, such as www.photobucket.com
. Then come back here and paste the link to your picture in a REPLY.
If you have more questions, let me know. I hope your tree will be able to recover.
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