Microbials To Treat Dollar Spot: An Environmentally Friendly Approach To Disease Management

Dollar spot, caused by the fungi species Clarireedia spp., is a common turfgrass disease that affects both cool-season and warm-season grasses, as well as certain agricultural crops. With a significant economic impact on industries like turfgrass and golf, the research and treatment of dollar spots have become crucial. In this article, we explore the symptoms, life cycle, growth conditions, and various methods of prevention and control, including the use of microbes as an environmentally friendly approach to managing microbials to treat dollar spot.

Symptoms of Dollar Spot

Dollar spot infects the leaves and stems of turfgrass, leading to the development of circular or irregularly shaped patches of light tan or straw-coloured turfgrass. These patches, approximately the size of a silver dollar, range from 10 to 40 mm in diameter. The affected grass blades become thin and brittle, causing a decline in the overall health and appearance of the turf. Additional symptoms include hourglass-like lesions on grass blades and the presence of white or pink cobweb-like aerial mycelium in early morning dew or high humidity.

Life Cycle and Infection Stages

Clarireedia fungi primarily reside in the soil and thatch layer of turfgrass. They can survive in infected dead plant tissue and wait for optimal conditions to grow and infect. The fungi can penetrate leaves directly, enter through cut leaf tips, or through stomata. Once inside the plant, they colonise cells, secrete enzymes and toxins, and cause tissue necrosis. When conditions are favourable, mycelium grows from infected tissue and spreads to nearby plants. Unlike other fungi, Clarireedia does not produce spores and relies on the movement of mycelium or infected leaf debris for dissemination.

Growth Conditions for Dollar Spot

Dollar spot thrives in warm and humid conditions, typically appearing in late spring or early summer. The disease is most active in temperatures ranging from 60 to 85 degrees Fahrenheit, with high humidity and dew. Fungal spores can survive in the thatch layer or soil for extended periods and can spread through equipment, people, animals, water, or wind.

Methods of Prevention and Control

To effectively manage and prevent dollar spot outbreaks, several preventative measures and management strategies can be employed:

• Proper irrigation management: Deep and infrequent watering, preferably in the early morning, can help prevent the development of dollar spots.

• Fertilisation: Maintaining a proper fertilisation program based on soil testing can keep turfgrass healthy and less susceptible to the disease. However, over-fertilization should be avoided, as it can increase the risk of disease.

• Cultural practices: Regular mowing, thatch removal, and aeration are essential. Proper mowing heights, removal of clippings, and aeration to improve soil drainage and air circulation can reduce the risk of dollar spot development.

• Fungicides: In severe cases, chemical control through fungicides can be effective. However, it is important to rotate fungicides with different modes of action to prevent the development of resistance.

• Inoculants: An environmentally friendly approach to disease management involves the use of inoculants containing beneficial microorganisms. These microbes, such as bacteria and fungi, compete with and suppress the growth of the dollar spot pathogen. Research has shown the effectiveness of inoculants in reducing the severity of dollar spot while being sustainable and environmentally friendly.
  
  

Conclusion

Dollar spot poses a significant threat to turfgrass and agricultural crops, making research and treatment of this disease crucial. Ongoing studies aim to classify the species more accurately and evaluate various treatment techniques, especially those that promote environmentally conscious mitigation steps and products. By adopting preventive measures and utilising environmentally friendly strategies such as microbials, the control and management microbials to treat dollar spot can be achieved effectively while minimising the impact on the ecosystem.