Thanks all...I will examine the tree closer and see where else it's got the canker. As you might see from at least one of the pics, it seems that the main trunk is affected, so pruning there will be impossible. I read something about copper? is that something to try? and you refer to making it healthier, like fertilizing? mulching? and thanks for the kitty compliment, she is a ferrel turned housecat and she's a polydactal and a real sweetie. Still a bit uneasy around strangers, but she has come a long way, the kitty in the first picture (bottom right corner, tiger striped) she was part of her ferrel family, when you would come within 10 feet of her, she would scramble, now she sits on my lap and purrs, she's a real lover and sweet too. I took in these 2 the calico's kitten and rehomed one other (they all got left behind when some trailers moved out from a neighboring area).

It looks as though you, or whoever drew the plan, mostly followed/paralleled the track of the Comcast, and maybe phone lines, (are the electric wires in front, or is it also in the back? If in front, does it run along the driveway into the garage?) as you decided where your SW bed was going to go - very clever. It would seem as though the planned spot for the oak (which I assume is replacing the HL next to the patio, since you didn't say) will be far enough from the lines not to have a problem. One thing you might definitely do, ASAP, is call both the power, phone and Comcast people and have someone come and mark where the lines run, unless the marks are still visible. That way, your memory maybe being off by a foot or three, there will be no nasty surprises. They'll do it for free - it's usually a "call-before-you-dig program", or some such name - since it saves mightily on their repair time! Digging the holes ahead of delivery is not a bad idea, although the crew coming to plant may have to do more work on them. YOu don't have to do it, esp. if you are paying for the job and not for the hour. If all they are doing is delivering, then having the holes, and having them deliver the trees next to the holes would be good. It wouldn't hurt, if the man (or woman) power is available, to place the plants in their planned spots, and take a few minutes to look at them from several angles, including inside and upstairs. You may see some minor tweaking that you can do, even at that stage. It's a LOT easier to re-dig a hole than to try to move a tree, or to kick yourself for the next umpty-ump years about how that tree would have been better over there, just a bit. A future tree near the play area/structure is an excellent idea. I am not sure a Sycamore is the best bet, as they can get very large, can be messy, and, if a friend's experience is common, can cause allergies in some people. If you do decide you want to put a tree there, start another thread, as this one is covering enough topics, and confusing readers enough, already!

The other problem with this tree is a rather large vertical crack starting from the ground and going right up. It's a frost crack - has been there for at least 2 years that I've noticed. From what I read, frost cracks on ash trees don't necessarily kill a tree but do give bugs an opportunity to crawl in there. After Rick's suggestion that it might be another borer, which I hadn't considered, I read about the Redheaded Ash Borer and the Banded Ash Clearwing Borer, native pests that attack ash trees. I'm quite certain there's something buggish in that tree, based on the woodpecker activity which is almost constant. I'm also thinking this tree is a goner - perhaps not from EAB but something else, slowly but surely. I'll still check it closely - I got some plants from southern Ontario a couple of years - is it possible for EAB to have travelled that way? Those plants are now planted right near that ash tree but that's got to be a stretch, no? Having to remove the tree will affect some plants that now benefit from the midday shade it provides (but they can be easily moved). Having to remove it will mean less ash seeds. Having to remove it give me the opportunity to plant something new there, and that's okay with me.

My guess from the photos is that it needs Nitrogen, it may also be deficient in something else, it looks like Magnesium deficiencies to me based on the leaves, though I would not expect to see that in the calciferous soils that are commonly found on the west coast. Soil pH effects nutrient uptake, so the first thing I would do is do a soil pH test, get home pH test kits for under $10 in most garden centers. This includes a small capsule of powder that you mix with a soil sample and water then compare colors on a chart. Do note if you have recently fertilized the soil it can throw off the readings if your soil sample is contaminated with any granuals of the fertilizer. (Don't trust he cheap electronic probe pH meters). If your soil pH is above 7 I would suggest the first step being to fertilize with a fast acting Nitrogen source, my first choice would be Ammonium Sulfate, available at better garden centers, Amazon, etc. Just be ware it can cause fertilizer burn if used too strongly. Or Calcium Nitrate if soil pH is below 6.5, though I think the chances of this are VERY low for southern California. If you want to stay Organic use Blood Meal as a fast acting Nitrogen source, though it is a little slower acting than the other two mentioned above. If you do need Magnesium, common unscented household Epsom salts are a great source of it, you can probably add a bit without much chance of overdosing, if you want to try just sprinkle half a cup of so evenly around the tree. p.s. if your pH is above 7.5 or 8 you may also have Calcium induced Iron Chlorosis, the solution is to add iron using something like ironite, and lower your pH over time through the addition of Sulphur, this is a long slow process though.