Rhizoctonia Rot of Strawberries: Causes, Symptoms, and Treatment

If you're a strawberry grower or enthusiast, you must have heard about Rhizoctonia rot. This disease is one of the most common problems that affect strawberries in both commercial and residential settings. In this article, we will discuss the causes, symptoms, and treatment of Rhizoctonia rot in strawberries in detail.

What is Rhizoctonia Rot?

Rhizoctonia rot is a fungal disease that affects the roots, crowns, and fruit of strawberry plants. The disease is caused by several species of fungi from the genus Rhizoctonia, with R. solani being the most common culprit. The fungus can survive in soil, plant debris, and infected plants for several years. It thrives in moist conditions and warm temperatures, making it a prevalent problem in humid and rainy areas.

Symptoms of Rhizoctonia Rot

The first symptom of Rhizoctonia rot is usually wilting or yellowing of leaves, which progresses to the entire plant's death in severe cases. However, the most noticeable sign of the disease is the brown, sunken lesions on the fruit, which are often mistaken for physical injuries. These lesions may start as small spots but enlarge and deepen over time, causing the fruit to become misshapen and unmarketable. If left untreated, Rhizoctonia rot can cause significant losses to strawberry growers.

Causes of Rhizoctonia Rot

Rhizoctonia rot is primarily caused by poor soil management and cultural practices that favor the fungus's growth and spread. Here are some of the factors that can contribute to the disease:

• Poor drainage: Excess water in the soil creates a humid environment that encourages the growth of Rhizoctonia fungus.
• Overcrowding: Planting strawberries too close together can lead to increased humidity and reduced air circulation, promoting fungal growth.
• High soil pH: The fungus thrives in alkaline soils (pH above 7).
• Low soil fertility: Nutrient-deficient soils weaken plants' immunity, making them more susceptible to fungal infections.
• Infected plant material: Using infected seeds, transplants, or soil amendments can introduce the fungus into the field.

Treatment of Rhizoctonia Rot

Prevention is the best way to manage Rhizoctonia rot in strawberries. Here are some measures you can take to reduce the risk of infection:

• Plant resistant varieties: Some strawberry cultivars are resistant to Rhizoctonia rot.
• Improve soil drainage: Add organic matter such as compost to improve soil structure and drainage.
• Control weeds: Weeds provide a breeding ground for the fungus and can spread the disease to strawberry plants.
• Rotate crops: Avoid planting strawberries in the same spot for more than two years to reduce the buildup of pathogens.
• Practice good sanitation: Remove and destroy infected plant material and avoid working in wet fields.

If your strawberries are already infected with Rhizoctonia rot, there are no chemicals or fungicides that can cure the disease. However, you can take the following steps to minimize the damage:

• Harvest affected fruits immediately to prevent further spread of the disease.
• Remove and destroy infected plants, preferably through incineration or hot composting.
• Avoid replanting strawberries in the same area for at least three years.

Rhizoctonia rot is a serious disease that can cause significant losses to strawberry growers. However, with proper soil management and cultural practices, it is possible to prevent and control the disease. Remember to always practice good sanitation and crop rotation to minimize the chances of infection. If you suspect that your strawberries are infected with Rhizoctonia rot, act quickly to limit the spread of the disease and save your crop.

Fig. 1: Rhizoctonia rot lesions on a strawberry fruit (Source: farmprogress.com)

strawberry diseases, Rhizoctonia fungus, fungal infections, soil management, crop rotation, cultural practices.