In our last post, we explained why avocado trees that are grown from seed take up to 15 years to bear fruit. In this video we are going to discuss one of the methods commercial growers use to solve this problem.
One of the most common ways of overcoming the juvenile phase is grafting a bud from an already established tree onto a young seedling. Depending on the condition, commercial avocado trees will either be grown using seed or clonal rootstocks.
Before we get started, here is a bit of background on why the avocado industry places significant importance on rootstock selection. The trees are highly sensitive to root diseases, which is caused by organisms like phytophtora. Some cultivars, like ‘Duke 7’ and ‘Dusa’, are more resistant to these pathogens and when used as rootstocks, can help prevent disease manifestation in the rest of the tree.
Propagating a seed rootstock involves 2 different plants: a seedling which is grown from a seed to become the rootstock, and a mature tree which will donate the scionwood.
Once the seedling’s stem has grown, the top part (including the leaves and branches) is pruned. A bud is taken from a mature tree and grafted onto the seedling. These buds will then develop into the canopy system and produce fruit. The root system will have the genetic characteristics of the seed, whilst the canopy will be a clone of the mature tree.
One of the problems with propagating avocado rootstocks directly from seed is that the grower will often not be able to guarantee his seed is ‘’true to type’’. In other words, even if the seed is taken from a cultivar like ‘Dusa’, cross-pollination may have caused the seed to have characteristics from another cultivar.
Therefore, another method was developed to solve this problem. Check out the next post to see how they do it.
Check out this improved method using the doube graft procedure.