Ian: I am not a disease expert on Colorado trees, but it puzzles me why you would choose to replace the infected (or not yet) Aspens as they "need to come down". Nor am I familiar with cytospora disease, but it is apparently quite contagious to nearby trees. To me, the most logical course of action with a line of trees that are either infected now, or will be in the next few years, would be to get them all out of there pronto. If you plan to eventually replace the trees with fruit bearing species, I don't see much reason to do that serially either. Since part of your plan seems to be the visual effect of a line of new trees, it would seem better to have them all be approximately the same age and stage of development, rather than several larger trees alternating with smaller ones. I certainly agree with the CSU analysis that the overall health of a tree, especially fruit trees that generally require a higher level of care than decorative species, depends at least partially on healthy soil with all the needed elements present. This can usually be achieved with soil tests, and amending as required. The use of organic mulches around fruit trees is one way to provide small amounts of micronutrients, and conserve soil moisture at the same time. But with fruit trees, pruning to keep the trees open to light and air, and prompt removal of branches beginning to show disease, can also contribute to long-term health. Dormant spraying with oil and fungicides like copper can also delay or eliminate many fruit tree maladies. You can accumulate a list of trees diseases with Latin names as long as your arm, but you will not really know whether fruit trees will prosper in your yard until you try it by planting some. Sure, there are lots of disease threats out there, and nearly all of us who grow fruit trees have to deal with them, but careful observation and attention, combined with prompt remedial measures when indicated, can go a long way toward controlling them or eliminating them entirely. Don Yellman, Great Falls, VA

May, on my acre of North St Louis glory I would probably just cut it flush with the ground. If it is only 12 foot tall how thick is the trunk? Maybe a foot across. Someplace large than that I can not cut flush with my chainsaw and they seem to linger. FWIW when I had a large white ash removed with its about three foot across trunk I had it ground. Three years later the soil where it was still is not right to plant in. The soil near the rotting 30 inch across stump I left for decoration when I removed a white ash almost a decade ago was and is much better. Maybe I just should have asked how large a yard do you have, how manicured it is, and whay your plans are for the spot. I'm long winded.

While some have woodland gardens with tree stumps in them there is always the possibility of Armillaria where stumps are present near plantings. And it does seem it could be a good idea to not plant where a stump has been ground into buried fragments. One of the most pervasive root rots, Armillaria spp., will survive in the soil on root pieces of susceptible hosts. This would caution one to thoroughly remove diseased roots from the soil, which would be in much closer contact with healthy root systems than topdressings would be. It is a different story, however, if one is foolish enough to amend backfill soil with wood chips. A researcher working with Rhododendron spp. lost plant material to Phytophthora root rot after amending the soil with 33% composted wood chips. Not only is this a poor practice for installing woody plants, it also casts doubt on the efficacy of composting to remove pathogens from wood chips A garden specimen can grow for decades and then be lost to Armillaria. British references have cautioned for years that stumps should be cleared out of woodland gardens before planting. Here is a link that might be useful: The Myth of Pathogenic Wood Chips

I can only positively recommend Penstemon "Huskers Red", German Iris, Japanese Anemone "Honorine Jobert" and a Daylily "Hyperion". I have had many plants survive under this tree, but not thrive includung Siberian Iris and Monarda. Actually, the Monarda has been all but eradicated. You can read the lists. but they aren't correct in all cases. Plant a small patch of sundrops and see what happens. My ace in the hole is Honorine. She takes time, but every fall there is a plethora of beautiful flowers and the foliage is always luxuriant. Some of the plants get black marks on their leaves which I blame on the Walnut, but since they are constantly sending out roots and spreading, the majority of them are healthy. I've decided to no longer obsess about these trees and if all else fails, let Honorine do her thing. I also have the poison ivy. Golden Rod seems to grow back there too. Also I found, what I thought was a dead tree trunk and trained a trumpet vine on it. I was a woundeed, but not completely dead Walnut. The vine is thriving.