Raspberries at Risk: Saving Your Canes from Deadly Purple Blotch.

Didymella: A Serious Threat to Raspberry Crops

According to TSN.ua: Didymella, caused by the fungus Didymella applanata Sass, is a severe disease that targets young raspberry canes and leaves, potentially stunting plant development. The first visible signs appear on new shoots of the current season, where purple spots emerge, typically concentrated around the buds. This fungus can persist in the soil for 8 to 10 years, making it especially challenging to eradicate.

Risk Factors and Prevention Strategies

Fungal spores begin attacking young growth in early summer when temperatures rise above 15°C (59°F). Conditions that increase the likelihood of Didymella infection include:

• Dense, overcrowded plantings
• Low-lying, poorly drained areas
• Excessive use of nitrogen fertilizers

In cases of widespread infection, cutting all canes down to the ground is recommended. During autumn, applying a 7% urea solution helps control the disease, whereas using a 2-3% copper sulfate solution can be risky. In early spring, treat plants with either a 1% copper sulfate solution or 7% urea. Systemic fungicides like 'Skor' or 'Magnicur Sensation' are used to protect new shoots. By mid-summer, biological products such as 'Fitosporin-M' offer an eco-friendly defense. To boost plant immunity, add anti-stress agents like 'Epin-Extra' to treatment mixtures.

A seasonal treatment calendar for raspberry care includes several key phases:

• Autumn: Focus on eliminating infection before winter dormancy.
• Early spring: Protect plants as they emerge from dormancy.
• Early summer: Prioritize safeguarding young, vulnerable shoots.
• Mid-summer: Ensure biological protection and good airflow around plants.
• Late summer to early autumn: Support recovery and strengthen the plants' natural defenses.

Adopting an integrated approach—combining fungicide applications with the removal of infected plant parts—is essential for managing Didymella and maintaining healthy raspberry plants.

Infection by the fungus Didymella applanata can significantly reduce raspberry yields, highlighting the need for effective agricultural practices.

Because the fungus can survive in the soil for many years, a systematic management plan is crucial to minimize risks and ensure stable crop development. Regular monitoring of plant health and quick action at the first signs of disease will help growers protect their raspberry plants and achieve a high-quality harvest.