System Article
Angular leaf spot is a common bacterial disease of pumpkins and other cucurbits that causes chlorosis and necrosis (death) of leaf tissue. This disease primarily affects the leaves of strawberry plants and is known for its distinctive angular leaf spots. It
#Strawberries
Overview Strawberry Angular Leafspot Disease is caused by the bacterium Xanthomonas fragariae. This disease primarily affects the leaves of strawberry plants and is known for its distinctive angular leaf spots. It can lead to reduced photosynthesis, weakened plants, and potentially lower yields if not managed properly. Symptoms 1. Leaf Symptoms: o Angular Spots: The disease is characterized by small, angular spots on the leaves. These spots are typically water-soaked, then turn brown or black with a yellow or reddish halo around them. o Leaf Margins: The spots often have angular or irregular edges, which is a distinguishing feature of the disease. o Leaf Drop: Severely infected leaves may drop prematurely, reducing the plant's ability to photosynthesize and impacting overall health and yield. 2. Petiole Symptoms: o Petiole Lesions: In some cases, the disease can affect the petioles (leaf stems), causing dark lesions that may weaken the leaf attachment and lead to additional leaf drop. 3. Fruit Symptoms: o Less Common: While less common, the disease can occasionally impact fruit, leading to small, sunken lesions on the fruit surface.
Disease Cycle 1. Inoculum Source: The bacterium Xanthomonas fragariae survives in plant debris, soil, and on infected plant parts. It can also persist in the environment for extended periods. 2. Bacterial Spread: The bacteria spread through rain, irrigation water, and mechanical means, such as infected tools or equipment. They can enter plants through natural openings, wounds, or damage. 3. Infection: Once introduced, the bacteria infect the leaves and other plant parts, causing the characteristic angular spots and lesions. The disease can spread rapidly under favorable conditions. 4. Disease Development: The bacteria multiply in the plant tissues and produce more bacteria, which can be spread to other parts of the plant and neighboring plants. 5. Bacterial Dissemination: As the infected tissues decay, they release bacteria into the environment, further spreading the disease. Favorable Conditions • High Humidity: The disease thrives in conditions of high humidity and frequent leaf wetness. • Warm Temperatures: Xanthomonas fragariae prefers warm temperatures, typically between 70°F and 85°F (21°C to 29°C). • Dense Planting: Crowded plantings and poor air circulation increase humidity around the plants, creating ideal conditions for bacterial spread.
Management Strategies 1. Cultural Practices: o Proper Spacing: Space plants adequately to improve air circulation and reduce humidity around the leaves. o Pruning: Remove and destroy infected leaves and plant debris to reduce the inoculum source. o Avoid Overhead Irrigation: Use drip irrigation to minimize moisture on the leaf surfaces and reduce the risk of infection. o Crop Rotation: Rotate strawberries with non-host crops to minimize bacterial buildup in the soil. 2. Sanitation: o Remove Debris: Regularly clean up plant debris and fallen leaves to reduce sources of bacterial inoculum. o Disinfect Tools: Use disinfected tools and equipment to prevent the spread of the disease from one plant to another. 3. Disease Resistant Varieties: o Variety Selection: Some strawberry varieties have partial resistance to Angular Leafspot. Consult local extension services or nurseries for information on resistant varieties. 4. Chemical Control: o Bactericides: Although less commonly used, bactericides may be applied as a preventive measure, particularly during conditions favorable to bacterial development. Consult with local agricultural extension services for recommendations on effective products. 5. Monitoring and Timing: o Regular Inspection: Regularly inspect plants for early signs of infection and take action promptly to prevent the spread of the disease. Conclusion Strawberry Angular Leafspot Disease, caused by Xanthomonas fragariae, can significantly impact strawberry production by causing leaf damage and reducing overall plant health. By understanding the disease cycle and implementing a combination of cultural, sanitation, and management strategies, growers can effectively manage and reduce the impact of this disease. Regular monitoring and timely interventions are key to protecting strawberry crops and ensuring a healthy, productive harvest.
