Lawn Diseases
Leaf Spot
Turf affected: Kentucky bluegrass (especially common bluegrasses), fescues and other lawn grasses
Symptoms: Small lesions on leaf blades. Dark coloured spots that eventually turn light tan but remain bordered by a dark brown outer edge. Eventually these plants die out and turn brown or straw coloured, this can occur in patches.
Disease occurrence: Spring, typically during time of cool, wet weather
Management: Mow the turf high (2.5 – 3 inches) to provide leaves that produce food for the plant and maintain a healthier lawn. Avoid excessive nitrogen fertilization in spring which can promote lush growth. Once area becomes “straw coloured” assume fertility application to encourage healthy turf and recovery. Manage thatch by aerating the lawn. This will also promote a deeper healthier deeper root system.
Fairy Ring
Turf affected: All species
Symptoms: Large arcs or rings consisting of very green grass, dead grass, mushrooms, puffballs or a combination of all.
Disease occurrence: Late March to early November
Management: Remove desiccating organic matter such as tree stumps, rotting lumber, etc… from the soil before planting. Provide proper fertilization (more nitrogen) and irrigation along with regular dethatching and/or aerating of the Turfgrass to help prevent the development of this disease. Fungicide treatment or soil removal may be necessary if fairy ring becomes a problem. If fairy ring symptoms consist only of mushrooms and there is no zone of dark green grass, the mushrooms can be raked off and disposed of. Since some of the mushrooms are poisonous, mushrooms should be removed or destroyed. Chopping them up with the mower is adequate, but if children or pets are present, it is probably best to collect the mushrooms and place them in the garbage out of their reach. While removing the mushrooms will not weaken or control the fungus, it will improve the turf’s appearance.
Red Thread
Turf affected: All species of grass.
Symptoms: Pinkish red threads that form around the leaf blades and bind them together. Eventually, the affected turf will turn brown. The red threads are most visible when the turf is wet and you may see red spores on your mower and shoes.
Disease occurrence: Early spring
Management: The best prevention for red thread is to aerate regularly and remove thatch. Mow at proper levels, reduce shade on the turf and follow a regular fertilization program. Collect and dispose of grass clippings when disease is present. Increased nitrogen and phosphorus fertility has been correlated to decreased red thread susceptibility. So, fertilizing on a regular schedule will eliminate one of the primary causes of red thread. Also, water deeply but infrequently early in the day to allow the leaf blade to dry off.
Brown Patch
Turf affected: Bluegrass, Fescue, and Ryegrass.
Symptoms: Circular brown patches up to 3ft in diameter that develop during hot, wet weather. Infected leaves become dark, wilt and die quickly when the disease is active. The entire patch will eventually become a brownish tan color.
Disease occurrence: Mid June to early September
Management: Avoid excessive fertilization with high nitrogen fertilizers in late spring or early summer. Reduce thatch to increase air circulation, and water deeply but infrequently early in the day to allow the leaf blade to dry off.
Dollar Spot
Turf affected: Bluegrass and Ryegrass
Symptoms: Straw-colored patches 2 to 6 inches in diameter. Hourglass shaped lesions with reddish-brown margins develop across the leaves.
Disease occurrence: Late March to early November.
Management: Drought soils and prolonged wet foliage are key factors for disease development, so water deeply but infrequently early in the day to allow the leaf blade to dry off. Regular fertilizations will help the turf to overcome the disease. Collect and dispose of grass clippings when disease is present.
Dog Spot
Turf affected: All species.
Symptoms: When your pet urinates on your lawn, it can cause the grass to burn out and yellowish dead spots will appear due to the high levels of nitrogen in their urine. It’s worse with female dogs because they typically have stronger urine, and they usually revisit the same spots, but this happens with male dogs as well.
Disease occurrence: Year round
Management: There are several ways to solve the problem of these unsightly dead spots:
- Saturate the place where your dog urinates with a large amount of water immediately after it does its duty. This will cause the nitrogen in the urine to be evenly distributed and diluted.
- Set aside one particular corner of your yard as your dog’s bathroom and train it to go there when it feels the call of nature. Cover the area with gravel or mulch so it can be easily replaced. This prevents dead spots in your lawn and helps to prevent odor from feces and urine.
- Be sure to keep your dog well hydrated in order to lower nitrogen levels in its urines naturally. Your dog should always have access to water at all times.