One of the privileges of working at ECHO North America are the interactions with ECHO Network Members, such as Noris Ledesma. Several months ago she came to ECHO North America and taught the Interns how to do Inverted Root Grafts on Mamey Sapote. In addition to tree size control benefits this technique reduces time to fruiting.
As with every graft budwood selection is a key place to start. Look for Budwood inside the canopy and along the branches instead of at the end of main branch. These will be slender and easier to graft. This post shares more details Mamey (Pouteria sapota) - Budwood Selection.
To select ideal rootstock look for a seed that has started to germinate, but has not yet pushed out any cotyledons. Remove it from the container and dust off any soil.
Invert the root so that it is pointed up. Cut off the tip of the tap root at a diameter that matches with your budwood diameter. Next make a cut 1.5 inches (~4cm) deep down the center of the tap root. Finally, on your budwood cut two cuts about 1.5 inches (~4cm) long, one on each side of the base. The result was a V shape with a fine point.
Insert the cut budwood into the cut in the tap root. Secure the graft union with a rubber band.
Repot the seed, burying any exposed rootlets. Label your graft with [Date - Species - Variety - Grafter - Comment]. Next, cover the graft with a clear plastic bag to reduce stress on the healing graft. Set the graft in a container of water and keep it moist, but not over saturated. Regularly observe the graft for new leaves pushing from the scion. Once new leaves are pushing and beginning to establish, open the bag to gradually over several days/weeks to adjust the humidity around the graft.
Special thanks to ECHO Intern Daniel Mbaiasde for the photos of his inverted root graft on Mamey.
If you would like more information on this technique check out this article! ihttps://www.cabidigitallibrary.org/doi/pdf/10.5555/20183290802
Do you use this grafting technique regularly or on other species? We’d love to hear from your experience.