Common spot of strawberry

Mycosphaerella fragariae 2

Common spot of strawberry is a plant disease affecting strawberry plants, caused by the fungal pathogen Mycosphaerella fragariae. This disease is also known as strawberry leaf spot or Mycosphaerella leaf spot. It is a significant concern for commercial strawberry producers and home gardeners alike due to its potential to reduce both the yield and quality of strawberry fruits.

Symptoms

The initial symptoms of common spot of strawberry include small, purple to red spots appearing on the upper surface of the leaves. As the disease progresses, these spots enlarge and turn gray to white in the center, surrounded by a red to purple border. Severely affected leaves may turn yellow and die, leading to premature leaf drop. In addition to leaf symptoms, the disease can also affect petioles, stolons, and calyxes, although less commonly.

Disease Cycle

Mycosphaerella fragariae overwinters in infected plant debris and begins producing spores in the spring, which are dispersed by wind and rain to infect new leaves. High humidity and moist conditions favor the development and spread of the disease. The fungus can produce several generations in a single growing season, allowing for rapid increases in disease severity under favorable conditions.

Management

Management of common spot of strawberry involves an integrated approach combining cultural, biological, and chemical strategies:

• Cultural Control: Practices such as removing and destroying infected plant debris, using resistant strawberry varieties, and ensuring proper plant spacing to improve air circulation can significantly reduce disease pressure.
• Biological Control: There are limited options for biological control of this disease. However, maintaining a healthy soil microbiome through the addition of organic matter can help suppress soil-borne pathogens.
• Chemical Control: Fungicides may be necessary in commercial production settings or severe cases. Application timing and selection of effective fungicides should be based on local extension service recommendations to minimize the risk of resistance development.

Importance

The common spot of strawberry is of particular concern due to its impact on the aesthetic and commercial value of strawberries. The disease can lead to significant economic losses by reducing the marketability of the fruit and increasing production costs associated with disease management.

Prevention

Preventative measures include selecting disease-resistant strawberry varieties, practicing crop rotation with non-host plants, and maintaining clean fields by removing weeds and plant debris that can harbor the fungus. Regular monitoring for symptoms and early intervention when the disease is detected can also help prevent widespread outbreaks.