Mango Top Grafting and Replanting: Operation Methods and Key Technical Points

Over the past decade, mangoes have been planted in contiguous orchards on hillsides throughout the south, and production has developed rapidly. However, large trees and new trees that have been planted for many years need top grafting and replanting due to poor quality or mixed varieties and low yields. The methods are:

1. Preparation before grafting. Before replanting, strengthen fertilizer and water management for the trees to be replanted. Prune the aboveground parts appropriately, removing diseased branches, dead branches, shaded branches, overly dense branches, and crossing branches; for perennial large trees, in spring and autumn, saw off the main and lateral branches at 1.2-1.5 m above the ground (saw in spring and graft in autumn, or saw in autumn and graft the following spring), leaving some small branches. After new shoots emerge from the saw cuts, keep only 2-3 evenly distributed new shoots per cut. After the new shoots mature and their diameter reaches 0.5-0.8 cm or more, grafting can be done on the new shoots. Stop fertilizing 15 days before grafting, which can slow sap flow and benefit grafting.

2. Grafting period. Graft when the sap is about to flow, that is, before new shoots emerge, when the rootstock and scion bark peel easily. The survival rate of top grafting and replanting is relatively low under high temperatures, low temperatures, or rainy weather, while spring grafting (March-April) and autumn grafting (mid-August to mid-September) can achieve a survival rate of over 90%. Although top grafting and replanting in May can survive, germination after survival coincides with high temperatures, and dieback is very likely to occur; grafting in October can also survive, but at this time drought and gradually declining temperatures occur, and after survival and sprouting, low temperatures cause slow growth, and new shoots may even be frostbitten or frozen to death.

3. Top grafting methods. From mother branches with excellent fruiting performance, select mature or lignified branches that are thick and free of pests and diseases from the outer canopy as scions. The methods include bud patch grafting, single-bud side grafting, and single-bud cut grafting. For trees whose branches and trunks have not been shortened, graft high on the original branches at 1 m to 1.5 m above the ground using bud patch grafting or single-bud side grafting; on new branches where the trunk has already been cut, use the cut grafting method, and bud patch grafting can also be used. When grafting, it is best to use extra-thin film for wrapping. Wrap the scion bud eye with a single layer of film; after survival, the sprouting bud can grow through the film, reducing the step of removing the film.

4. Untie at the proper time. After the graft survives, the film should not be removed too early, otherwise the new shoots will wither. Generally, untying when the first new shoots turn green is safest; untying too late will affect the thickening growth of the rootstock and scion and cause rot. For bud-branch side grafting and bud patch grafting, 30-40 days after grafting, first cut off the branch tips 8-10 cm above the graft union, and after the new buds become mature branches, untie and perform the second cutting of the rootstock, that is, cutting to just above the graft.