Dematophora root rot (Rosellinia root rot)
Dematophora necatrix
Also Known As - Rosellinia root rot (Dematophora root rot )What is Dematophora root rot (Dematophora necatrix, Rosellinia necatrix)?
Dematophora root rot, also known as Rosellinia root rot or white root rot, is primarily caused by the fungus Rosellinia necatrix. Although it is not commonly found in landscape settings, it can have severe consequences for various woody plants, including fruit trees like apple and pear, avocado, cotoneaster, holly, poplar, and viburnum. Infected plants exhibit wilting, yellowing, and stunting. The roots decay and turn black, leading to their deterioration. Rosellinia produces cobwebby mycelia, which can be seen on the lower trunk, in soil over infected roots, or beneath the bark.
How does Dematophora root rot (Dematophora necatrix, Rosellinia necatrix)?
Rosellinia necatrix reproduces and spreads through several means. The fungus can persist in soil for years through dried pieces of infected bark and wood. It produces cobwebby mycelia that can grow from infected roots or spread through the soil when conditions are moist. Root contact or grafting between nearby plants of the same species allows for the transfer of the fungus. Additionally, spore-forming structures called coremia can be produced, contributing to further dissemination of the disease.
Symptoms
1 - Effects on plants
• Infected plants experience wilting, yellowing, stunting, and root decay, leading to a decline in health and eventual death. • This can result in reduced crop yields, loss of ornamental plants, and economic losses for farmers.
2 - Effects on soil
• Decay of infected roots contributes to organic matter decomposition, affecting soil structure and nutrient availability. • The disease can also lead to soilborne inoculum buildup, increasing the risk of future infections. • The spread of Dematophora root rot can disrupt natural ecosystems and impact biodiversity.
Solutions
1 - Preventive Measures
• Source healthy plants from reputable nurseries to reduce the risk of introducing the pathogen. • Implement proper site preparation techniques, such as ensuring good soil drainage and avoiding waterlogged conditions. • Plant susceptible hosts on raised beds or soil mounds in areas with poor drainage. • Provide optimal cultural care, including appropriate watering, fertilization, and overall plant health management.
2 - Cultural Practices for Management
• Promptly remove and dispose of infected plants to prevent further spread of the disease. • Break root grafts by trenching around the infected site to inhibit fungal spread between nearby plants. • Clean soil and remove root debris to minimize the presence of inoculum before replanting. • Establish a dry (unirrigated) zone in the area where an infected plant was located to prevent soil movement and water runoff.
3 - Expert Consultation and Monitoring
• Seek expert advice from a plant pathologist or agricultural extension service if Dematophora root rot is suspected. • Promptly confirm the diagnosis to ensure appropriate management strategies are implemented. • Regularly monitor plants for symptoms and early detection of the disease to take immediate action if needed.
