Notes on Apple Diseases
Russeting is the presence of brown scars of the surface of the fruit.
There are many different causes for russeting on fruit, which include
frost damage, fungal infections like powdery mildew, yeast and bacteria
growth, herbicide drift and phytotoxicity.
Period of activity
Russeting can occur on the fruit throughout the growing season.
Monitoring and Thresholds
There are no thresholds for russeting.
There are several causes for russeting and some are controllable, while
others are not. As a result, it is often difficult to manage this disease
in the orchard. Several important tips for russeting reduction in your
orchard are as follows:
- Select varieties that are less susceptible to russeting (e.g. Empire,
- Maintain an open canopy to increase airflow and decrease drying time
for leaves and fruit.
- Use a preventative fungicide program to manage diseases that cause
- When you plant an orchard, locate trees in sunny locations with good
air drainage to reduce frost damage.
- The use of Surround and gibberellins may help to reduce russeting
in susceptible cultivars.
- Avoid the application of pesticides during slow drying conditions
or when temperatures exceed 32° C.