tomforester, how I wish it were so simple. When you take a cutting, a sequence reactions take place dependent upon how the cutting is treated. Leave it lying around and the cut surface seals over to protect against loss of moisture. That is why we stick the cutting in the propagation medium asap; or if time passes, we make a fresh cut to (re)stimulate the rooting processes. All regenerative activity arises from the cambium layer - the "green sap" which we see when we scratch the bark. At first, cell division occurs - one cell becomes many. Next, cell differentiation takes place ("division of labor"). The "daughter cells" (I am not sexist; my text books may have been) begin to acquire different characteristics. In this case, the influences of temperature, lack of light and optimum moisture content produce root tissue and these differentiate into cortex and stele (the two I remember) and that's how Mother Nature makes our cuttings root. There is a separate process called "osmosis". This determines if water will flow into or out of a cell. If the solution (water with stuff dissolved in it) outside of the cell is stronger than the solution inside the cell, then water only will run out of the cell and the cell solution will become toxic. This happens when we over-apply fertilizer or we do not irrigate on time. In either case water only runs out of the cells and cell solution becomes toxic. And you might induce this when you place the cutting in a liquid with " special liquid fertilizer for citruses" dissolved in it. Do you see that "a lot of longitudinal grooves with exacto-knife at the bottom of the shoot to maximize the contact surface area" will aggravate the 'reverse osmosis' reaction?

"..If the hackberry is deciduous then you should start the air layer at the end of winter, right before it wakes up" I don't know where you got this info from, but it is not a very good idea. And will most likely not work at all. 1) If you air layer before there is foliage, there is nothing to provide the sucrose to develop roots. 2) If you "leave thin strips", the wound will just heal over, and not develop roots. "...this way it will still have some of the cambian layer to supply the upper portion," The cambium does not supply the leaves with anything. The cambium is the pathway for sucrose made by photosynthesis in the leaves, to travel to the roots. The inner core is the pathway up from the roots that supplies water and nutrients to the leaves. When we sever the cambium, water and nutrients can still reach the leaves who, who in turn send the sucrose developed (energy) back to the roots for storage (down through the cambium). Once this energy reaches the severed section of cambium, it has nowhere to go and collects there. This initiates the formation of roots at that spot. If the cambium is not entirely severed, there is still a pathway for energy to travel to the roots. And the tree will begin to heal the severed section while still functioning normally. It is a one way loop -

Hi Lou. Sorry to have a "non-answer" for you, but I'll share a little related experience that may be useful. I've tried to root pear cuttings several times and just haven't been able to get root hairs out of the cuttings! I will admit to not being very good at this kind of thing, but I did give it a shot four or five times. No go. On the other hand, pears take to grafting quite nicely, thank you. If you're new to grafting, (or even if you're not)check out Joreal's tutorial: http://citrus.forumup.org/about500-0-asc-0-citrus.html I've grafted pears primarily with ordinary old cleft grafts, but a couple of split and bark grafts have worked out too. If those pears are really, really special and might do well in Montana, is there any way I could beg/trade/other a couple of scions? Thanks, Mark

Pj, it sounded like you tried many methods but NOT air layering, which is well described on this site in other posts. In your case I would have taken cuttings, put them in barely moist towelling in a zip-lock and put them in the vegetable crisper of the fridge for a week. This puts them into dormancy. When they come out of the fridge, I would forget the baggie method for rooting and put them into a very well drained light potting medium (barely moist) in 16 oz plus clear plastic cups with drain holes. Put them on a warming tray covered with a plastic dome to keep humidity high. Your climate may already do both of these 'warm and moist' stages for you. When I do this method, I can usualy see good root development in a couple of weeks as well as budding and leafing out. Don't be in a rush to transplant, and remember that excess of water is a killer at this stage. Air layering works fine too, you just have to be patient, but you can do it anytime. However, it may take months for the branch to throw out roots, or just weeks. You could also try ground layering too if you have branches close to ground and can pin or weight them there for some time. My two cents... John.