Virus-free rootstocks

There are large differences in performance between the various selected M9 clone rootstocks. Their origin is a critical factor. M9 clones generally perform better and are to be preferred. Freedom from viruses is essential for the vitality of a rootstock. Virus-free rootstocks are superior in all respects ... 

M26. This rootstock is less demanding than M9 in terms of soil requirements and has rather better anchorage. M26 virus-free is about 50% more vigorous than M9, and this is why the commencement of cropping is later. 

M9 EMLA UK > M9 T337 first virus-free M9 rootstock... 

At present we consider that the optimum planting stock is a well-developed, virus-free, 2-year-old tree on a Quince C rootstock. With some cultivars, e.g. Williams Bon Chretien, an interstock is needed. On poorer sites, or when replanting, it may he advisable to use Quince A or Quince Adams. In most cases Quince C should he given preference, however. These trees produce faster and grow less vigorously as a result, so the tree structure is simpler. 

---