Brown spots spreading across leaves and fruit, growth that visibly stalls, apples and pears that end up malformed and begin to rot on the branch: that is scab, a fungus that attacks apple, pear and plum trees alike. Moisture is what lets it in, so a thorough autumn leaf clean-up is what keeps a harvest clean.
As it forms brown spots on fruits and leaves of trees, scab can lead to their growth clearly slowing down.
You’ll also observe that fruits are malformed, and even start to rot.
Follow the steps listed here, and your harvest will be protected and effectively guarded against scab.
Like all fungal diseases, moisture is the most relevant appearance factor. When in conjunction with heat, the risk of seeing scab colonize your fruit trees is even higher.
It is often at the end of spring that this fungus appears, and it will develop during the entire fruit formation phase.
But sometimes scab appears only in fall when moisture is very present, especially since nights grow longer.
Almost everything that works against scab is preventive, and each step has its own moment in the year. Here is what the article recommends, and what each task is actually for.
| Measure | Type | Season | What it does |
|---|---|---|---|
| Pick up and burn all fallen leaves | Preventive | Mid to late autumn, once leaves have fallen | Destroys the fallen leaves the fungus overwinters on |
| Mow around the tree | Preventive | Late autumn, after leaf fall | Speeds up the breakdown of the fallen leaves |
| Gather fallen fruit | Preventive | Through fruit formation and after | Stops dropped fruit lying and rotting on the ground |
| Spread compost at the foot of the tree | Preventive | Autumn | Feeds the tree as part of the autumn clean-up |
| Spray Bordeaux mixture | Preventive | Autumn after leaf fall, then early spring | Protects buds and young growth; renew 2 to 3 times according to rainfall |
| Remove and burn infested leaves | Curative (the only option) | As soon as spots are seen | Cuts down the source of infection while the fungicide is renewed |
Read across the rows and the pattern is clear: the autumn tasks decide how much scab you will face the following spring.
Preventive care is the best solution
There isn’t really any curative treatment
Note that the fungus overwinters on leaves that have fallen from the tree when diseased.
In spring, the ascospores, which are how this fungus reproduces, are ejected in the air during rainy days and reach the trees born by the wind.
That is why it is critical in fall to pick up and burn all the leaves of your apple trees, pear trees and plum trees.
