Thanks everyone!
I have a few experiments going on with Lemon Zest and Here is a quick breakdown. I have two LZ Mango trees ordered from Florida and presumably on turpentine rootstock. They were both approximately the same size when I ordered the trees but one tree was planted into the ground sooner than the other. The LZ that was planted into the ground first busted out with 4-5 flushes if I remember correctly. Because LZ is known to be a vigorous upright variety, I decided to let it grow uncontrolled with no pruning to simulate a word case scenario of uncontrolled growth.
This tree flowered and fruited the first year but the growth was so vigorous and due to the Turpentine rootstock( this is assumption but there are multiple members that can vouch) the vegetative growths were long and weak with an extremely droopy habit typical of what we see from Florida grafted Mango trees but exacerbated by the extreme vigor of the LZ. The majority of growth showed signs of nutrient deficiencies.
The brother tree was slightly delayed in growth because it was in a pot for several more months before planting into the ground and it did not flower the first year. For this tree, I implemented a tip pruning regimen following Dr Campbell's recommendation. Scaffold branching for both these trees start approximately 3-4 feet from the ground. This second tree has flushed about three times and so far the growth is not droopy although some of the growth showed signs of nutrient deficiencies.
My third LZ is actually three different branches of LZ grafted onto a Lavern Manilla rootstock. These grafts took with vigor and flushed three times with tip pruning. These grafts show no signs of droop growth and also do not show any signs of nutrient deficiencies.
My fourth LZ is my Double Stone Grafted plant from this thread:
http://tropicalfruitforum.com/index.php?topic=16549.0 It has flushed three times in three months since grafting onto double Kent seedling rootstock. The trunk has more than doubled in size and it is naturally forming ultra low scaffold branches which may be beneficial for this extremely vigorous upright grower. I would like to keep this tree low, bushy and very fruitful so I feel that very low scaffold branches are required as the foundation.
I also have DSGed LZ on Indian Mango rootstock, Ataulfo, Glenn, Haden, TA, and mixed ( mono and poly) rootstocks. I have also spread some of these DSGed LZ trees to different parts of San Diego in order to get more data points for future analysis.
So far, the best rootstock to use for DSGing is Kent seedling rootstock but any vigorous mono seedling seems to work really well. For long term health of the tree, one Mono and one Poly seedling may give better disease resistance.
Simon