Hi, I have an unusual terrain, where there are many hawthorns, even large ones, is it true that they are a good apple tree rootstock?
in fact the hawthorn (crataegus monogyna) was traditionally used as a rootstock for many fruit plants, such as pear, apple, peach, plum; unfortunately this type of graft has been abandoned over the years, due to the fact that hawthorns are often very susceptible to a disease, called bacterial fire blight. It is a disease caused by a bacterium, called Erwynia amylovora, which affects pome fruits in particular, such as apple, pear, cotogni, even pyracanth, cotoneaster and hawthorn. This disease did not once exist in Europe, and therefore the hawthorn was used without problems as a rootstock, being a very robust and vigorous plant. For some years this bacterium has come to Europe from North America, and is spreading. Fortunately, the European Union is trying to contain the spread of this bacterium, and therefore there are many commercially available rootstocks for fruit crops, resistant to the fire.
The plants affected by this bacterium have foliage that suddenly dries up, starting from the apexes of some branches towards the inside; as the common name says, it seems that the plants have been ruined by heat, as if someone had access to a small fire near the affected branches. The only method we now know to contain the disease is to remove the affected branches and destroy them; if the disease spreads too much, the entire plant is burned. This bacterium spreads in the air, thanks to the wind, and tends to hit the plants on the soft tissues of the shoots, or where there are scars or cuts due to pruning. Once penetrated into a plant, it develops and spreads very quickly.
If you believe that your land can become an orchard tomorrow, you can try to use your hawthorns as rootstocks, but be prepared to watch very often for the presence of this type of disease, which can quickly become destructive, and can force you to remove and destroy all the plants on your land.