Question: Some of the fruit on my tree has gone brown and rotten, and is covered in light brown pustules. What is the cause?
The fruit is affected by the fungal disease brown rot.
Question: What disease has caused the brown, scabby lesions and cracks on the fruit?
These are the fruit symptoms of apple scab.
Question: Why do some of my fruit have black marks on the outside?
The fruit may have been affected by the fungi causing blemish diseases known as sooty blotch and flyspeck.
Question: Fruits are falling from my tree and have been eaten inside. Which pest is responsible?
The two common culprits are apple sawfly and codling moth.
- Fruit affected by the larvae of apple sawfly often fall from the tree in June or early July. Sometimes sawfly larvae feed only beneath the skin of the young fruitlet rather than burrowing into the core – these fruit usually survive but have a long ribbon-like scar on the exterior by the time the fruit is ripe
- Those attacked by codling moth don’t fall until the fruit is ripe
Question: Why are some fruit on my tree bumpy and distorted?
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.
Question: The fruits from my tree have brown specks inside and a bitter taste. What has gone wrong?
This is a disorder known as bitter pit, caused by low calcium levels in the developing fruit.
Question: Why do large numbers of fruit often fall from my tree in mid-summer?
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.
Question: My tree has hardly any fruit! What has gone wrong?
Possibly causes of unproductive fruit trees include:
- Poor weather restricting the activity of pollinating insects during flowering
- Frost damage to the flowers
- Birds (e.g. bullfinches) eating the flowers
- Lack of a pollinating partner - you may need to plant another apple cultivar
- Biennial bearing – some trees have a habit of alternating a year of heavy cropping with few or no fruit the following year
- Young tree – it may take a few years for fruiting to start (this can vary according to the cultivar and the rootstock on which it is growing)
- Poor pruning technique
- Poor growing conditions, e.g. drought, excess shade, lack of nutrients