Apples
are one of the most widely grown of hardy fruits and are available in a
wide range of varieties and cultivars.
One thing that should be understood about apples is that
the are two components to the tree. The roots and the top-growth that
actually come from two different plants. The top growth - the apple variety
is chosen for its fruiting qualities, this is grafted onto the rootstock
which is chosen for hardiness, disease resistance and also the size the
tree will ultimately grow to. The rootstock determines the size that
the tree will grow to and not the variety. There will be one of a number of possibilities from
"very dwarfing" rootstocks that will allow an apple tree to be grown in a
container, to "extremely vigorous" where you'll need a ladder to
reach much of the fruit. Most nurseries these days will sell apples
grafted onto "dwarf" or "semi-dwarf" rootstock which
are relative phrases, you might imagine dwarf trees to be below waist
height, but they'll actually be 7-10 feet tall with semi-dwarfs about
12-14 feet tall.
When positioning an apple tree ensure that it has
enough room all round to develop to its full size. A sunny position is
required to get good crops and should be as sheltered as possible too. If
you live in an area with late frosts, select late flowering varieties.
No apples are consistently and reliably self-fertile
and where possible, should always be planted with other varieties that
flower at the same time to ensue cross-pollination and so achieve better
fruit set.
Apple trees can be easily gown in a variety of forms,
bush, fan, espalier, cordon or flat against a wall or fence. The
easiest form to train is a bush and is also the most useful shape for most
gardens. The aim is to achieve an open crown with 8-10 branches radiating
from a short trunk. Apples are readily trained however, more so than
almost any other fruit tree and the other forms may be achieved relatively
easily.
Pruning should take place in mid to late winter,
while the tree is dormant, but after the harshest weather is over. Initial
training removes the leader to just above 3 or 4 strong lateral buds, over
the next three years, a network of laterals should be encouraged to
produce the required 8 - 10. Other branches not selected for the main ones
should be pruned to just 4-5 buds in length, The strong laterals should
have about 1/4 of the seasons growth cut from them at this time. All cuts
should back to outwards pointing buds so that shoots don't cross over. Any
dead or damaged wood should be removed all together.
Subsequent pruning is to prevent any shoots taking over
from the main branches and to keep fruiting spurs back to 4-6 buds in
length. Allowing any longer fruiting spurs will run the risk of them
breaking under the weight of the fruit which will damage the shape of tree
and allow disease in.
Restorative pruning of neglected trees, should
take place over 3 or 4 years if possible. If a tree has been neglected for
some time, it will have long pendulous branches that bend considerably
under the weight of fruit and some may already have broken. Cut any that
have broken to a point beyond the break so the tree can form a clean wound
seal. Cut back no more than 1/4 - 1/3 of the elongated branches in any one
year to no less than 1/2 of the previous length (unless removed
altogether). The tree will probably produce a large number of vigorous
shoots in response - many where you don't want them to be. These should be
removed or encouraged as appropriate.
Apple problems
Apple Sawfly - In early to mid summer the apples drop
soon after forming and have a maggot hole in
the side that is surrounded by sawdust like frass (yes - caterpillar
dung has a special name! - frass). Control is by picking and destroying affected
fruits before they fall off and the moth escapes. If there have been heavy
infestations in the past, then spraying with bifenthrin at the point where the
petals fall can be effective.
Aphids - Twisted curled or puckered leaves and shoots
which on inspection have hundreds or thousands of tiny green, black or
pale colored insects. Spray at first sign with a systemic insecticide or
your preferred organic alternative.
Codling moth - In mid to late summer small holes in
fruits and maggots feeding near the core. Treatment is by the insecticide bifenthrin in early
summer followed by another application about 2 weeks later. The timing of the
application can be gauged using pheromone traps to see when the moths are most
active. Alternatively if you don't want to apply an insecticide, then pheromone
traps can catch enough moths if the trees are reasonably isolated to reduce the
number of maggoty apples. You will never really totally control codling moths.
Bitter Pit - Small brown indentations in the skin and
fruit of the apples. Caused by a calcium deficiency, treat be applying
lime to the soil and watering in well (takes over a year to have an
effect) or spray with calcium nitrate if available.
Red Spider Mite - Leaves become mottled and fall off,
branches can be almost bare except towards the tip. Fine webs are
found on the leaves and tiny
red mites may be seen, but not easily. Spray with rotenone, malathion or
dimethoate in June. This is worse in dry, hot years and rarely a problem
outdoors in cooler areas in normal or damp years.
Apple Scab - Black/brown scabs appear on the fruits with
similar scabs on the leaves, though green/gray in color. Fruit may also be
small and misshapen, secondarily split and become infected with fungal rots. Venturia inaequalis
fungus is the culprit which over winters on
stems and fallen leaves. Fallen leaves should be raked up and burnt or otherwise
disposed of out of the garden. Spray the tree with a fungicide containing
carbendazim or mancozeb, some apple cultivars are resistant. Trees with
overcrowded branches are more susceptible, so pruning to open the crown will
help, the disease is more prevalent in damp years.
Brown
Rot - Soft brown spots on the apples and white or yellow fungal growths
grow on these. Remove and destroy (not on the compost heap) affected
fruits, fallen, on the tree or in store. Spray with a general fungicide or
benomyl.
Apple canker - Patches of dead or
dying bark on the branches and trunk. Twigs are killed as the diseased
bark rings the twig. Cut out and burn affected parts, stumps can be
painted with a proprietary canker paint.
Powdery
mildew - White powdery deposit anywhere on the tree which distorts leaves
and shoots. Remove affected shoots and spray the tree with a general
fungicide, benomyl or thiophanate-methyl.
Capsid
bug - Puckered regions on apples
with a brown corky swelling at the center. Capsids feed on immature
fruits so killing some of the
developing cells and so there's a region that is not so well developed as the
surrounding region, the brown corky growth is a sort of tree allergic reaction
to the saliva of the bug. The damage is only skin deep and the fruits are
perfectly edible. Severe damage in previous years can be treated by spraying
with bifenthrin or pyrethrum at petal fall.
