Where the problem of inadequate pollination is a more permanent one, whole or part trees of the main variety can be grafted over to a pollinating variety using frame working or top working grafting techniques (see Garner, 1988).
- Work conducted at Long Ashton Research Station showed that Malus species could perform well when grafted as branches into trees of the cropping variety (Williams, 1976).
- If the trees of the main cropping apple variety are suspected as being virus infected, grafts of Golden Hornet or Winter Gold should not be used, as they are very virus sensitive.
- In these situations, it is possible to use the less sensitive Malus aldenhamensis and Malus Hillierii.
- When grafting crab apple pollinators into trees of the main commercial variety, it is essential to control the vigour of the latter in the first few years, so as to allow the graft to develop without too strong competition.
- Grafts should be placed in a dominant position on the tree.
- Once established the grafted crabs can compete with the main variety quite effectively.
- Indeed, M. aldenhamensis and M. Hillieri frequently prove to be very strong growers as grafts.
- Grafting other fruiting apple varieties into trees of the main variety (e.g. James Grieve grafted into Cox) can also prove effective in pollination.
- However, there is seldom sufficient time to pick the pollinating branch and failure to do this can depress flowering in the subsequent year.
- Also, unless great care is exercised it is very easy to remove the branch during winter pruning (Williams, 1966).