A dreaded fungal disease in orchards, scab is recognizable by the brown spots it causes on fruits.
Tips for preventing and getting rid of it.
Read also :
- Apple scab
- Fight against fruit rot
- Improve fruit harvest
Scab: well known in pear and apple trees
If it also affects medlar trees and mirabelliers, it is especially on pear trees and apple trees that scab is known to wreak havoc. Fruits of infected trees show brown spots which, if they grow in size, cause them to rot.
Contamination is caused by the spores of a fungus present on dead leaves. First, the leaves of the tree become covered with downy spots during primary infection.
It may stop there, but if the summer is rainy, the spores spread by the leaf spots will germinate on the flowers and fruits of the tree. This is called a secondary infection.
Means of controlling scab
In the event of contamination, it will be difficult for you to save the current harvest, but certain actions will allow you to avoid a new infection the following spring.
> In the fall, collect and compost fallen leaves.
> At the time of bud break, treat your trees with Bordeaux mixture.
> In the event of frequent rains, a treatment with sulfur, before and after flowering, will ensure the eradication of the spores.
Varieties not very susceptible to scab
Scab is a particular concern in areas in rainy spring and summer. In these areas, it is better to opt for old varieties which are not very sensitive to them: apples "Belle de Boskoop", "Reinettes du Mans" or "Reinettes de Flandres"; "Conference" or "Williams" pears. Some new varieties - like 'Ariane' for apples - were designed to withstand it.
Conversely, varieties such as "Golden" or "Cox Orange" for apples, "Beurré Hardy" or "Beurré Giffard" for pears, as well as their hybrids, are particularly susceptible to scab.
Ask your nurseryman for advice when buying your fruit tree.