It looks like either black oak or northern red oak. The white stuff is from spittlebugs. The froth covers the nymphs while they are feeding. They are unlikely to harm the tree seriously.

Concur with Northern Red Oak. Black Oak quite rare in metro Denver.

I don't know about the spittlebugs. However, I just saw a large Shumard Oak (close relative of Northern Red) at the Denver Botanic Gardens that has a bad infestation of kermes scale, and the damage looks quite similar to these photos--dead branch ends (mainly the new stem and foliage growth of the year) shriveling up and later blowing off in strong winds. You should be able to see the kermes scale if it is present since they are 1/8 to 3/16". Hope you don't have two problems there.

Here is a link that might be useful: Kermes Scale N. Red Oak

The dead branch tips look not unlike the 'flagging' that we commonly see subsequent to periodic(and, to a lesser degree, annual) cicada oviposition damage. In photo #2, the larger branch, to the lower right, displays what appears to be healing linear cicada oviposition wounds from a previous year .

and.. perhaps.. those holes int eh leaves.. MIGHT indicate that a hail storm rolled thru .... can you rule out severe storms.. before you came to the property???

second.. in one pic.. all the damage is under the canopy .... from the angle of the pic anyway .... there is natural selection done by the tree... perhaps it is just sacrificing that limb ..

regardless.. its a rather large tree .... other than removing the dead branches.. no treatment is necessary ... trees can withstand and cope with just about any plague that is sent to then ... anything you can dream up... other than proper pruning... is a waste of your money .. and time ....

seriously .. a plague f locusts could come by .. denide the tree ... and odds are extremely high... with nothing from you.. it will be just fine ..

let it do its thing .... rather than poison the earth trying to HELP it ...

good luck

ken

i hate when i hit send.. before previewing all my spelling corrections .... lol

forgive the cryptic method of communication ... lol

ken

I am not familiar with oak problems in your area. However, when I see the dying leaf signs such as you have posted on mature trees I always ask if there is a gas line running beneath the trees? On numerous occassions when this type of damage shows up in one area by itself it is wise to ask the gas company to check for leaks if such a line is present. On one occassion the gas company found that a leaking gas line installed on the other side of a street had a leak so severe gas was following the extensive tree roots, injuring maples on the opposite side. This may not be applicable to your situation but should be kept in mind when dealing with older neighborhoods.

I've seen extensive damage to branch tips on a wide variety of trees due to squirrels. That's another possibility for you to consider. Nandina, do you remember the huge 'epidemic' of squirrel damage to the live oaks in Beaufort? Everyone (including me, probably) was convinced that it was some kind of fungal infection until Michael Murphy started investigating. It was a drought year, and the squirrels had been BUSY!!!

I don't have any good ideas about the icky stuff dripping from the tree. I do not, however, think that it's from spittlebugs.

I disagree with Ken that trees can withstand most anything that comes their way. Urban trees face circumstances that can set them up for failure, infestation, and infection. Such factors as compaction, street and sidewalk construction, poor soil, vehicle emissions, some street lighting, and an assortment of other 'trials and tribulations' can each (or all) take chinks out of a tree's natural armour.

If these trees are valuable to you in terms of shade and/or added property value, I'd seriously consider finding a couple of ISA (International Society of Arboriculture) Certified arborists to come out for an evaluation and estimate on any needed work, if required.

You might even be lucky and find that there is a well-informed certified arborist at your local extension office. That would be worth a phone call.

Rhizo is expressing some good thoughts. Sometimes even the experts have to do some detective work to figure out tree problems. I agree that the white fuzzy 'stuff' falling from the trees is not spittle bug. If I were dealing with the problem a sample would be at my extention office tomorrow for testing/identification. Why are people so reluctant to call in experts when confronted with unusual tree problems? They should realize that the good, certified arborists are alert to the various disease and insect problems around the country and continue to watch carefully for them possibly appearing in their territory. Foreign cargo delivered to our shores has unleased a number of hidden 'tree killers'. We all should be alert to the unusual and consult with the experts. This appears to be one of those situations.