Strawberry root rot

The causative agent of this disease is the soil-borne fungus Rhizoctonia fragariae, a pathogen that primarily attacks the root system of strawberries. It is a highly resilient organism that can survive in the soil for several years by forming sclerotia, making it a persistent challenge for strawberry growers globally.

The main host crop for this pathogen is the cultivated strawberry. While it affects plants of all stages, the disease is particularly devastating in nurseries and newly established plantations. The fungus penetrates the roots, disrupting the plant's ability to absorb essential water and nutrients from the soil.

Key symptoms include the browning and eventual blackening of the roots. The fine feeder roots, which are crucial for nutrient uptake, are often the first to rot, leading to a brittle root structure. Above ground, the symptoms appear as stunted growth, leaf chlorosis, reddening of older leaves, and a progressive wilt that does not recover even with regular irrigation.

Environmental conditions play a decisive role in the disease cycle. The pathogen thrives in moist, cool to temperate soil environments, with temperatures between 15°C and 22°C being most conducive to infection. Poor drainage, soil compaction, and high levels of soil salinity can exacerbate the severity of the outbreak by creating stress for the plants.

The economic impact of Rhizoctonia fragariae is significant, as it leads to reduced fruit yield and poor berry quality. In severe cases, large portions of a plantation may collapse, leading to total crop loss. The long-term presence of the fungus in the soil often forces growers to avoid replanting strawberries on infested sites for many seasons.

Strategies for management and prevention involve:

• Sourcing only certified, disease-free nursery plants for new plantings.
• Implementing strict crop rotation practices, avoiding known hosts of the fungus.
• Improving soil aeration and drainage to prevent waterlogging, which favors the pathogen.
• Applying biocontrol agents, such as beneficial fungi, to suppress the growth of Rhizoctonia.
• Sanitation measures, including the removal and destruction of infected root systems and plant debris.