Strawberry Plant Disease: Phomopsis Leaf Infection and Rotting of Fruits
In the heart of the agricultural landscape, Ohio strawberry farmers face a persistent challenge: Phomopsis leaf blight. This fungal disease, caused by the organism Phomopsis obscurans, can lead to significant losses and has been a growing concern in recent years.
The fungus survives overwinter within infested plant debris or infected plant parts, ready to strike when conditions are favorable. Symptoms of Phomopsis leaf blight on strawberry leaves start as circular spots, similar to leaf spot disease, but often have a reddish halo. These symptoms are most visible on older leaves near or after harvest.
While the fungus remains dormant in infected leaves early in the growing season, it can become active when conditions are right, typically developing later in the season, often during or after harvest in Ohio. This is when the economic impact of Phomopsis leaf blight can be felt, although it remains relatively minor in Ohio compared to other regions.
Effective management of Phomopsis leaf blight in Ohio strawberry crops involves a combination of cultural practices and fungicide applications. Cultural practices include water management, field sanitation, crop rotation and site selection, and proper spacing and air circulation.
Water management involves irrigating strawberries at the soil level rather than overhead to minimize leaf wetness, which encourages fungal growth. Field sanitation requires the removal and destruction of infected plant debris promptly to reduce fungal inoculum sources. Crop rotation and site selection are essential to limit pathogen buildup, while proper spacing and air circulation help improve airflow and speed leaf drying, thereby reducing favorable microclimates for the fungus.
Fungicide management typically involves fungicides labeled for Phomopsis management in strawberries, applied preventively or at early disease onset. Common classes include Botran (captan + iprodione), Pristine (boscalid + pyraclostrobin), Quadris Top (azoxystrobin + difenoconazole), and other azole-, strobilurin-, or dicarboximide-based fungicides. Fungicide applications should follow label recommendations for timing and frequency.
While the specific fungicides effective against Phomopsis leaf blight in Ohio strawberries were not detailed in the provided search results, cultural practices to reduce leaf wetness and inoculum, along with timely fungicide sprays, are generally recommended strategies for managing this foliar fungal disease.
Controlling weeds within the planting is another important cultural practice for successful strawberry production. Weakened strawberry plants due to Phomopsis leaf blight can result in reduced yields the following year. In favorable conditions for disease development, Phomopsis leaf blight can cause defoliation and, in some cases, death of plants.
It's crucial to use certified disease-free plants for planting and to avoid varieties that appear to be highly susceptible to leaf blight. The disease primarily affects older leaves of strawberry plants in the eastern United States, particularly in Ohio. Always remember that while fungicides are available for control of leaf blight, emphasis should be placed on cultural practices and variety selection.
This fact sheet was originally published in 2008, but the strategies for managing Phomopsis leaf blight in Ohio strawberry crops remain relevant today. For detailed, region-specific recommendations, farmers are encouraged to consult local extension services such as Ohio State University Extension.
The scientific study of Phomopsis leaf blight and potential solutions for its management in Ohio strawberry crops involves aspects of soil science (as microclimates within the soil and water management affect fungal growth), pest management (since Phomopsis leaf blight is a destructive fungal disease), and health-and-wellness (as healthy plants are less susceptible to disease and yield better crops).
Effective pest management strategies for Phomopsis leaf blight often include the prevention and management of medical-conditions (such as reducing leaf wetness to limit fungal growth) and the use of certified disease-free plants for planting to minimize the initial inoculum of the disease.
