A brown patch on the apple, a suddenly wilted shoot, orange-red dots on the pear leaf: fruit trees show their diseases openly, you just have to be able to read them. And that is the first and most important step, because the right diagnosis decides the right measure.
This article is your identification helper for the five commonest fruit tree diseases. You learn how to recognise each, how dangerous it is and what helps. And you will see: against most of them, prevention works better than any spray.
First identify, then act
The commonest mistake is to spray some product without knowing what the tree even has. A fungus needs a different answer than a bacterial disease, and a rust something other than a fruit rot. Some diseases even require you to keep an eye on the neighbour, because they alternate between two hosts.
So the close look pays off: where does the damage sit, on leaf, fruit or shoot? What colour and shape is it? And which tree is affected? With these three questions you almost always reach the right diagnosis.
The five commonest fruit tree diseases
Damage and tree at a glance
- Apple scab
Olive-green to brown-black, velvety patches on the leaves, later corky, cracked patches on the apples. Affects apple and pear. A fungus that loves damp springs.
- Fire blight
Shoots wilt suddenly, turn brown-black and curl like a shepherd's crook, as if burnt. On apple, pear, quince and ornamental shrubs. Dangerous and notifiable.
- Brown rot (Monilia)
Brown fruit rot with pale spore cushions in rings, plus the blossom and shoot blight, where flowers and shoots die back from the tip. On cherry, plum, apple and apricot.
- Pear rust
Bright orange-red spots on top of the pear leaf, with grid-like brown spore structures beneath. Needs juniper as a second host nearby.
The fifth of the group is peach leaf curl on peach and nectarine. In spring the young leaves blister, curl and turn red, until at last they drop. Let us look at the most striking damage pictures more closely.
The symptoms in pictures
What helps against nearly all: prevention and hygiene
However different the diseases are, the cornerstones of defence are much alike.
Plant robust varieties
The biggest lever. There are scab-resistant apple varieties and less susceptible pears. When planting anew, the look at the label pays off especially.
Keep the crown airy
A regular cut lets light and air into the crown, the foliage dries quickly and fungi have a harder time. More on it in Summer pruning of fruit trees.
Consistent tree hygiene
Gather fallen leaves, remove mummified fruit from the tree and cut out dead, affected shoots. That takes the pathogens' overwintering quarters away. Affected material goes in the residual waste, not on the compost.
Break the host alternation
Pear rust needs juniper, above all the savin, as its second host. If one stands in the garden or next door, removing it is the most effective measure against the rust.
With fire blight, report rather than spray
If the suspicion of fire blight is confirmed, follow the plant-protection authority's instructions. Here fast, correct action counts for more than any home remedy.
First read, then act. Leaf, fruit or shoot give the disease away, and against most of them an airy crown helps more than any spray.
The core rule for fruit tree diseases
Frequently asked questions
How do I recognise apple scab?
By olive-green to brown-black, velvety patches on the leaves and later corky, cracked patches on the fruit. It appears above all in damp springs. Scab-resistant varieties and an airy crown are the best prevention.
What do I do if I suspect fire blight?
Do not prune yourself but inform the responsible plant-protection authority. Fire blight is notifiable and highly contagious. Typical are suddenly wilting, burnt-looking shoots that curl like a shepherd's crook.
Why do I get pear rust every year?
Because a juniper or savin stands nearby, the second host of the fungus. Without this host the rust cannot complete its cycle. Removing the juniper in the surroundings is the most effective measure.
Can I still eat fruit with brown rot?
Rotten fruit affected by Monilia, no. Healthy fruit from the same tree, yes. What matters is to remove the brown mummified fruit consistently from tree and ground, because they are the source of infection for next year.
Is chemistry the only answer to all this?
No, quite the opposite. Robust varieties, an airy cut and consistent tree hygiene prevent most diseases entirely without any spray. How to prevent with little effort in general is in Biological plant protection.
