Phytophthora trunk rot

Phytophthora cactorum:

Phytophthora cactorum is a soil-borne pathogen that causes crown and root rot in various fruit and ornamental plants. This pathogen affects a broad range of hosts, including strawberries, raspberries, apples, ornamental trees, and shrubs. Here's an informative description of Phytophthora cactorum, including its appearance, identification, and management:

Appearance:

Crown and Root Symptoms:

1. Crown Rot: Infected plants may exhibit symptoms of crown rot, where the base of the stem near the soil line becomes discolored, often turning brown or black.
2. Root Rot: The pathogen infects the roots, causing rotting and decay. Healthy roots may appear water-soaked and turn dark as the disease progresses.

Above-Ground Symptoms:

1. Wilting and Decline: Infected plants may show wilting and overall decline, as the root and crown damage compromise the plant's ability to take up water and nutrients.
2. Leaf Discoloration: Foliage may exhibit yellowing or browning, starting from the lower leaves and progressing upwards.
3. Dieback: In severe cases, dieback of branches and shoots may occur, leading to stunted growth and reduced yields.

Identification:

1. Crown and Root Examination: Carefully inspect the crown and roots of affected plants for signs of rotting and discoloration.
2. Symptomatic Foliage: Look for yellowing or browning of leaves, wilting, and dieback in the upper parts of the plant.
3. Soil Sampling: Conduct soil tests to detect the presence of Phytophthora cactorum in the planting area.

Management:

1. Well-Drained Soil:

   • Improve Drainage: Ensure proper soil drainage to reduce the risk of waterlogged conditions that favor Phytophthora infections.

2. Resistant Varieties:

   • Plant Resistant Cultivars: When available, choose plant varieties or cultivars that are resistant or tolerant to Phytophthora cactorum.

3. Avoid Overhead Irrigation:

   • Drip Irrigation: Use drip irrigation instead of overhead irrigation to minimize soil splash and reduce the spread of the pathogen.

4. Soil Amendments:

   • Organic Matter: Incorporate well-rotted organic matter into the soil to improve its structure and drainage.

5. Fungicide Application:

   • Fungicidal Treatments: In commercial settings, application of appropriate fungicides may be considered. Consult with local agricultural experts for recommended products and application schedules.

6. Sanitation:

   • Remove Infected Plants: Promptly remove and destroy infected plants to prevent the further spread of the pathogen.
   • Clean Equipment: Disinfect gardening tools and equipment to avoid transmitting the pathogen.

7. Crop Rotation:

   • Rotate Crops: Implement a crop rotation strategy to reduce the buildup of Phytophthora cactorum in the soil.

8. Monitoring:

   • Regular Inspection: Periodically inspect plants for symptoms of crown and root rot, especially during wet conditions that favor disease development.