Identifying and Preventing Lawn Diseases In Guelph

Guelph homeowners often face various lawn diseases that can harm their lawns. In this article, we’ll explore the top 5 lawn diseases in Guelph and provide tips for prevention and treatment, helping you maintain a healthy and attractive lawn.

Brown Patch

Brown patch is a fungal disease that causes circular patches of brown, dead grass. It thrives in warm, humid conditions and is most common in the summer months.

Prevention and Treatment:

  • Improve air circulation by regularly mowing and dethatching your lawn.
  • Water your lawn deeply and infrequently, preferably in the early morning.
  • Apply a balanced, slow-release fertilizer to avoid excessive nitrogen levels.
a patch of grass that has been mowed down.

Dollar Spot

Dollar spot is another fungal disease that appears as small, silver-dollar-sized patches of brown or straw-colored grass. It can affect various grass species and is more prevalent in under-fertilized lawns.

Prevention and Treatment:

  • Use a balanced fertilizer to maintain proper nutrient levels in your lawn.
  • Avoid overwatering and water early in the day to reduce humidity.
  • Remove infected grass clippings to prevent the spread of the fungus.

Red Thread

Red thread is a lawn disease characterized by reddish-pink thread-like structures on the grass blades. It is caused by a fungus that favors cool, damp conditions and often affects lawns with low nitrogen levels.

Prevention and Treatment:

  • Ensure your lawn has adequate nitrogen by using a balanced fertilizer.
  • Improve drainage and avoid overwatering to reduce dampness.
  • Mow regularly and remove infected grass clippings to limit the spread of the disease.

Snow Mold

a spider web on the ground in the grass.

Snow mold is a fungal disease that occurs in early spring as the snow melts. It appears as circular patches of matted, discolored grass and can cause significant damage to the lawn.

Prevention and Treatment:

  • Rake leaves and remove debris from your lawn before winter to improve air circulation.
  • Avoid excessive nitrogen application in the late fall.
  • Gently rake affected areas in the spring to promote drying and recovery.


Rust is a fungal disease that causes an orange or yellowish powdery substance on grass blades. It usually occurs in lawns with slow growth and inadequate nitrogen levels.

Prevention and Treatment:

  • Apply a balanced fertilizer to encourage healthy growth and prevent nutrient deficiencies.
  • Water your lawn deeply and infrequently to promote strong root development.
  • Mow regularly and remove infected grass clippings to minimize the spread of the disease.


a magnifying glass over a field of grass.

Being aware of the common lawn diseases in Guelph and taking preventive measures can help you maintain a healthy, attractive lawn. Regular lawn care, including proper fertilization, watering, and mowing practices, can reduce the risk of these diseases and promote a thriving outdoor space.

FAQs On Lawn Diseases In Guelph

Should I use fungicides to treat lawn diseases?

Fungicides can be used to treat certain lawn diseases, but they should be considered a last resort. Focus on proper lawn care practices and preventive measures to reduce the need for chemical treatments.

How can I improve my lawn’s resistance to diseases?

A healthy lawn is more resistant to diseases. Ensure your lawn receives adequate nutrients, water, and air circulation through proper fertilization, watering, and mowing

practices. Additionally, overseeding with disease-resistant grass varieties can help improve your lawn’s resilience against diseases.

Can lawn diseases spread to other plants in my garden?

A: Some lawn diseases may spread to other plants in your garden, but most are specific to turfgrass species. Nonetheless, it’s essential to monitor your entire landscape for signs of disease and take preventive measures to protect all of your plants.


Colin Thomas MacMillan

Colin Thomas MacMillan, CEO of Riverwood Landscape, boasts over 8 years of expertise in landscaping and 3 years in transportation and logistics. A prominent figure, he serves as a board member for the Waterloo Chapter of Landscape Ontario and has been a vital part of the community for five years. Recognized for his insights, Colin has contributed to major industry events, including LeadsCON 2023. His entrepreneurial journey in landscaping began post-high school, driven by a lifelong aspiration and self-taught skills. Outside work, Colin's interests span history and video games, and he's dedicated three years to learning German, reflecting his commitment to personal growth. His professional ethos emphasizes a resilient, people-first approach, advocating for mastering current tasks and prioritizing quality in business and client relations. An avid reader of industry articles and an active networker, Colin's dynamic approach to professional development cements his status as a leader and an inspiration in landscaping and logistics.

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