Apples are easy to grow, productive, and there are cultivars, shapes and sizes for every garden. They can be susceptible to a range of pests (such as the woolly aphid pictured above), diseases and disorders, but in most cases action can be taken to prevent or control the problem. Susceptibility to the problems differs between cultivars – you would be very unlucky to have a tree that suffers from all of the problems listed below!
Here we give answers to many of the common problems encountered. They are grouped by the area of the tree affected: shoots; leaves and flowers.
Most common problems
Take a look at some of the common problems you might encounter on an apple tree.
No, this is a harmless lichen. A build up of lichen near the shoot tips can suggest your apple tree is low in vigour. In which case, concentrate on some winter pruning and spring/summer feeding to promote more active growth.
No, it is a pest called woolly aphid. The brown-black aphids secrete the white wax as a form of defence.
This is the disease powdery mildew. Heavy infection can reduce the vigour of the tree.
Your tree is affected by the disease apple scab. This disease can also attack the fruit (see below).
The most likely cause is a disease called silver leaf, which can also cause branch dieback.
The shoots are infested by aphids. A number of species can affect apple trees – some species leave the tree in summer to find other host plants, whereas others remain on the tree. The sticky substance is honeydew produced by the aphids, and this can lead to the growth of sooty moulds. The uncommon rosy leaf-curling apple aphid causes leaves to become distorted and red. Rosy apple aphid is a frequent pest and causes yellowish green curled leaves; it can also affect the fruit (see below).
The caterpillars of a number of moth species will eat the leaves of apple trees.
Distorted young leaves full of small holes may have been damaged by capsid bugs.
These are mines produced by caterpillars of the apple leaf-mining moth. No significant damage is done to the tree, so no control measures are required.
The fruit is affected by the fungal disease brown rot.
These are the fruit symptoms of apple scab.
The fruit may have been affected by the fungi causing blemish diseases known as sooty blotch and flyspeck.
The two common culprits are apple sawfly and codling moth.
If the fruits are undersized, with a pinched appearance at the eye end, it is likely that the affected fruits were infested earlier by rosy apple aphids. If there are isolated, corky bumps then capsid bugs may have been responsible.
This is a disorder known as bitter pit, caused by low calcium levels in the developing fruit.
The most common cause is a phenomenon known as the June drop (although it can occur in July as well as June). This is a natural process, during which the tree reduces its total crop to a level whereby the remaining fruit can be adequately supplied with nutrients until they are mature. If the initial fruit set has been poor (see below) then the June drop will be reduced. The extent of the drop can also vary according to the cultivar and the age of the tree (young trees are more commonly affected).
Some pests and diseases can cause fruit drop, as can adverse growing conditions such as severe drought.
Possibly causes of unproductive fruit trees include:
AphidsApplesApples and pears: summer pruningApples and pears: renovating old treesApple cankerApple scab and pear scabBitter pit in applesBlossom wiltBrown rotCapsid bugsCodling mothCoral spotFireblightHoney fungusMussel scalePhytophthora root rotPowdery mildewsReplant diseaseRosy apple aphidSilver leafSooty blotch and fly speck of applesWaterlogging and floodingWinter moth caterpillarsWoolly aphid
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Lucy, mum, part-time lectureer & RHS member
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cdals on 16/05/2014
apple trees with branches of many leaf bunches of small narrow leaves
david robertson on 15/07/2014
Dave, R 15/7/2014. Apple scab, (Worcester Permain) I cleaned up all the leaves, sprayed the tree, and the ground, last two years, no sign of disease, spray every 2 weeks, Bayer systhane fungus fighter.
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