Sooty Blotch: A Fungal Disease Affecting Pear Trees
Introduction
Sooty blotch is a common fungal disease that attacks pear trees, leaving behind dark gray smudges or blotches on the fruit’s surface. This disease can significantly impact the appearance and marketability of pears.
Symptoms of Sooty Blotch
Pear trees infected with sooty blotch exhibit the following symptoms:
- Dark gray or black smudges or blotches on the skin of the fruit
- The smudges or blotches are actually fungal strands
- Pears may appear dirty or handled with sooty fingers
- The disease can detract from the appearance of the fruit, making it less appealing to consumers
Causes of Sooty Blotch
Sooty blotch is caused by a complex of fungi, including:
- Gloeodes pomigena
- Zygophiala jamaicensis
- Leptodontium elatius
- Peltaster fructicola
- Geastrumia polystigmatis
These fungi overwinter in infected plants and thrive in wet springs and cool temperatures.
Impact of Sooty Blotch
Sooty blotch primarily affects the appearance of pears, making them less marketable. The disease does not penetrate into the flesh of the fruit, so it does not pose a health risk to consumers. However, it can significantly reduce the value of the crop for commercial growers.
Cultural Control of Sooty Blotch
Preventing sooty blotch requires cultural care practices that reduce the risk of infection:
- Pruning: Pruning pear trees opens up the canopy, allowing sunlight and wind to penetrate, which helps dry out the fruit and reduce moisture levels that favor the growth of fungi.
- Fruit Thinning: Removing excess fruit from the tree ensures that the remaining fruit has adequate space to dry and receive sunlight, reducing the likelihood of sooty blotch development.
- Mowing: Keeping the orchard floor mowed prevents low-hanging fruit from coming into contact with wet grass, which can contribute to sooty blotch infection.
- Brambles Removal: Removing brambles from the orchard area helps eliminate a major host for the fungi that cause sooty blotch.
Chemical Control of Sooty Blotch
Fungicides can be used as part of a comprehensive sooty blotch treatment program. It is important to follow label directions carefully when using fungicides.
Conclusion
Sooty blotch is a common fungal disease that can impact the appearance and marketability of pears. By implementing cultural control practices and using fungicides when necessary, growers can reduce the risk of infection and protect their pear crop.
