The speaker at our meeting on 18th November was Michael Abel, a former commercial fruit grower and lecturer at Writtle College. Michael started by emphasising that the subject of his talk was top fruit – primarily apples, pears and plums – and not soft fruit such as strawberries and raspberries and currants. There are many other more exotic varieties of top fruit like figs, peaches and apricots, figs and nuts but generally these are more demanding and sometimes not very productive.
The size of a fruit tree depends on the rootstock on which it is grown by grafting. Fruit trees on their own roots will grow too large for most gardens. Root stocks are classified as either dwarfing or semi-dwarfing and will produce trees varying from a height of 2 metres up to 6 metres. The smallest size should be used only for trees grown in containers as a patio plant. Apart from determining size, rootstocks have the benefits of greater stability, earlier fruiting, limited uptake of water and nutrient, better disease resistance, improved fruit quality and longer storage life. The variety of fruit tree that is required is grafted on to the root stock and this means that one tree can be grafted with different varieties, producing a ‘Family Tree’.
Fruit trees depend on pollination either by wind or insects for fruit production. Cross fertilisation is much more productive than self-fertilisation so a fruit tree needs to be in reasonable proximity to another one ( crab apples will do the job). Fertilisation and seed development need warmth so productivity may be restricted in a cold Spring.
Michael then went into detail about pruning, using a number of sample branches to make his points. The purpose of pruning is to reduce tree size and promote vigour for fruit production. A key thing to look for is the angle of growth of a branch or shoot. Vertical growth will be very vigorous not fruitful and downward growth is generally weak. These should be pruned out as horizontal growth is the most productive. Use winter pruning to promote vigour and prune in summer to reduce it. Make sure you understand the difference between fruit buds which are fat and vegetative buds which are more pointed. Most fruit trees are spur bearers which means that fruit is borne on side shoots but some, like Bramley apples, are tip bearers and cutting off branch ends means cutting off potential fruit, which can’t be helped sometimes in controlling size.
Pruning is also used for disease control by cutting out dead wood and fungal infections. Letting in air and light will reduce scab and promote good fruit colour and bud formation. Fruit size can be improved by generous thinning of fruit in the early stages of growth.
The remainder of the talk was devoted to pest and disease control. Michael dealt at some length with the question of whether you should spray with pesticides. His conclusion is that it is not very effective and has so many disadvantages that you shouldn’t do it. There are other more effective strategies. The basic one is to buy varieties that are bred with some degree of disease resistance. Prune mildewed branches or, in summer, leaves. Grease bands or barrier glue will stop ants getting at beneficial insects and prevent female winter moths climbing to the males waiting for them in the upper branches. Rake up fruit tree leaves to reduce the incidence of overwintering scab. The scourge of maggots in plums can be controlled with pheromone traps ( available together with many other pest controls from Agralan). Michael’s final advice was to do everything you can to promote the well-being of beneficial insects such as ladybirds, lacewing, hover flies and earwigs and to feed birds which will eat vast quantities of caterpillars. Agralan also sell biological controls. Trunk guards may be necessary where deer or rabbits are a problem and cherries will need netting to keep birds off.
A selection of Michael’s photographs:
Our next meeting will be our Christmas Party on December 16.