Apple and Pear Bark Canker
Some apple trees are susceptible
to infection by canker – rough lumpy areas on the trunk or branches.
Cox’s Orange Pippin is one of many trees that seem to get infected
with this disease.
It is caused by a fungal spore entering the bark. The first signs
are usually leafless twigs or twigs with small shrivelled leaves.
Closer inspection will reveal cracks in the bark – exuding a sticky
substance, or at the later stages of infection, lumps – best
described as carbuncles!
Canker can also spread to the fruit -
resulting in the fruit turning brown and dying on the tree - or sometimes emerge
It is probably the most serious of all apple tree diseases,
and often left until it is too late to do anything.
Splits and Lumps on the bark of Apple and Pear Trees.
Causes of Apple and Pear Canker
The fungus spores of Apple and Pear Canker
usually enter the tree bark from pruning wounds and other damages – even damaged
fruit. It is also more prevalent where the tree is suffering other stress
symptoms – maybe as a result of waterlogged soil, or lack of feed, leading to a
general demise of the tree’s health.
Once you start to notice Canker disease, it
will have already taken hold beneath the bark. For it is out of sight where it
first starts - just under the bark of the Apple tree. The infection then starts
to 'lift' the bark, and the infected wood can be seen beneath. The affected area
of bark will show white or red spots or pustules of the Canker Spores.
How to treat and cure Canker Disease.
There are chemical controls, but physical
attack is the first option for badly infected trees.
Cut out the affected areas on small branches with a sharp knife – or remove the
branch completely. Make sure that you cut back to clean wood, and that there is
no infected (brown) tissue left in the area.
Larger ‘carbuncles can be cut away with an axe – if you are used to using one –
or a hammer and chisel.
ALL cut off sections should be burned, or sent to rubbish in sealed container.
Do NOT try to compost these cut offs. Paint the cut away areas with Canker
Badly infected trees are probably best
removed, as they rarely get back to full health. It may take a few years for the
tree to die from a bad infection of Canker, during which time it will realease
spores to affect other trees in the area. The spores are easily carried by the
wind - or even rain splashes from infected fallen leaves.
Proprietary Bordeaux mixture can be used as a preventative, or to help contain
the spread of the disease. Apply twice in the Autumn – right after fruit
picking, and then again as the leaves start their autumn colour change. Treat
health trees as well as those infected with Canker disease. Dithane 945 can also
be used to control and contain Canker disease in the early stages, as can
Mancozeb. Read the manufacturers' labels before use.
The spores can overwinter on fallen leaves, so cleanliness is also important.
Again, do not compost the leaves from trees affected by Apple Canker.
Apples that are resistant include Lord Lambourne, Discovery, and Ellison’s
Orange. If it is a particular problem in your area – avoid planting Cox’s Orange
Pippin – Sad!