Lawn Care Corner: Not All Lawn Brown Spots Are Created Equally! - National Association of Landscape Professionals

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Lawn Care Corner: Not All Lawn Brown Spots Are Created Equally!

tall-fescue-drought-tolerance
The picture illustrates a tall fescue clump in a stand of Kentucky bluegrass ryegrass lawn.
Photo: FMC Professional Solutions

The summer months bring about environmental conditions that challenge the development, growth, and health of cool-season grasses. Conversely, warm-season grasses thrive in the summer months. However, the hot and humid weather conditions promote pathogens that could impede turfgrass health, if not managed properly.

The most common impact of the summer conditions is the appearance of discolored, brown areas in the lawns that require LCOs’ attention and the need for appropriate diagnosis and management. Simply put, brown areas in the lawn can be due to a lack of water as a result of dry weather or improper irrigation coverage. They could also be caused by the presence of disease, which requires the three necessary conditions for disease development: susceptible grass type, environment, and pathogen.  

What are common turfgrass issues in July that can be mistaken as drought?

During July, the appearance of brown areas in the lawn can be commonly mistaken for dry spots due to lack of rain, drought, or an improperly functioning irrigation system. It is why LCOs would want to take a closer look because not all brown spots are created equally. For example, the appearance of circular, brownish patches about 12 to 18 inches in diameter or larger would require a closer look; particularly, if upon inspecting the soil, it feels moist and appears to receive enough water from irrigation. Drought stress can quickly be ruled out in this case. LCOs often end up checking for insects and diseases, as well. In case of the presence of disease, it is important to identify the problem correctly so the issue could be managed with the use of the proper fungicide and possibly other cultural practices.

How can an LCO determine the true cause of drought-like symptoms?

The easiest way to determine if a lawn is under drought stress is to check the irrigation system to make sure it is running the appropriate amount of time, ensure the sprinkler heads are applying even coverage to the area and also check if any heads are broken and need to be replaced. It is also important to check the frequency and duration the irrigation system is running based on the requirements of the grass type. Sometimes homeowners get their irrigation system activated in the spring, but they forget to adjust as the weather conditions change from spring to summer.  

As the weather gets warmer, plant leaf temperature increases accordingly. This drives higher demand for water. Turfgrass plants absorb water through the root system so it dissipates through the leaves to lower the leaf temperature and naturally “cool off” through evapotranspiration. When water deficits occur in the soil, this triggers drought-like symptoms usually observed as slight discoloration, or the beginning of leaf wilting or leaf folding. LCOs can tell by easily seeing footsteps on the turf or from the mower tracks. It is best to check the irrigation for even coverage and increase the watering frequency and duration to meet the lawn water needs and to keep the leaf temperature within an acceptable range for proper cooling. It wouldn’t take long before the lawns start going dormant and turning brown to survive in the absence of adequate soil moisture.

Offering irrigation tune-ups and inspections is a great add-on service for any LCO. This not only helps the customer but also allows the LCO to have a little more control over one aspect of maintaining the lawn.

What are the best watering and mowing practices during a drought?

It is important to maintain best practices of watering and mowing throughout the growing season. Under drought conditions, these practices do not change but become more important for LCOs to be aware of. For example, maintain optimum mowing height for each grass type and avoid scalping are well-known best practices of mowing. These become even more critical as drought-stressed lawns could be harmed from a lower height of cut or worse from scalping as it could expose the crown to excessive heat and desiccation.

The same applies to irrigation. It is best to water consistently and be aware of the coverage of the sprinkler heads, irrigation frequency, and duration. Generally, it is important to water deeply and infrequently. This can be setting the sprinklers for 2 to 3 days per week, and program them to come on in the early mornings and avoid watering in the evenings. Depending upon the irrigation system and its output, program the sprinklers to run for 30 to 45 minutes per zone. It is best for LCOs to educate the customers on these best practices and consider routine irrigation maintenance checks by professionals.

During a drought, it is important to make sure that the lawn is watered adequately to ensure that it gets enough water to meet its needs. When there are watering restrictions, it is important to observe and follow the local community guidance. LCOs may decide whether or not to continue watering if the restrictions are fairly rigid or won’t allow for adequate watering. Remember that lawns that are tolerant to drought will recover quickly when rainfall resumes and clients should not be too concerned about the brown appearance.

Are there any turfgrasses that withstand drought pretty well?

In the months of July and August, it is not uncommon for the air temperatures to soar and rainfall to be less frequent, leading to a water deficit in the soil. Without irrigation or rainfall, lawns will start to show signs of wilting and turning brown. While this may look alarming, the lack of water triggers a survival mechanism within the plant tissue, called dormancy. Grass types vary in their adaptability and tolerance to drought stress. The following common grass types have excellent tolerance to drought: Bermudagrass, Zoysiagrass, and Kentucky bluegrass. However, it is important to know that drought tolerance depends on a variety of factors including genetics, geographic adaptation, soil type, and relative tolerance over time.  

Are there certain areas of the lawn that are more prone to drought stress?

Generally, full-sun exposed areas tend to be more prone to drought stress because of the extended exposure to direct sunlight and its desiccation effect. Areas next to sidewalks or roadsides can also be prone to drought since concrete and asphalt tend to hold in heat that radiates onto nearby grass.

Grass types that are well-adapted to drought can tolerate extended periods of drought without any permanent damage. The lawns would recover normally with 2 to 3 weeks and resume growth and healthy color. Lawn areas in the shade or partial shade maintain their color because of the cooling effect of the shade and the reduced loss of water from the soil surface.

What are the symptoms of damage from drought conditions?  

Damage from drought appears as straw/brown color and matted turf with no signs of growth or “life.” Drought damage is not apparent at the onset of the dry period but LCOs would notice damaged turf when rainfall conditions resume, and good growing conditions are present. Areas that do not recover with adequate water, rainfall, and favorable temperatures can be assumed damaged by drought if all other factors are ruled out such as diseases or insects. The drought-damaged areas will have to be sodded or seeded.    

Created in partnership with the experts at FMC True Champions.

Ben Hamza

Ben Hamza, Ph.D., is a product development associate director with FMC Professional Solutions.

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