Lawn Disease Management
Lawn problems can be challenging and frustrating. It is important to assess what might be the cause of lawn problems and receive proper treatments. Contact Us and we can come do an assessment if you have a serious lawn problem.
Necrotic Ring Spot
Colorado’s most common lawn problem is Necrotic Ring Spot (NRS). A common misperception is that it is a grass problem and can be fixed by replacing the turf with new sod. NRS is a soil borne fungus that affects Kentucky Bluegrass. Necrotic Ring Spot can be suppressed by a multi-front approach all working together. The main factors that affect NRS are irrigation, nitrogen, cultural practices, fungicides, and overseeding.
Water is an important factor for Necrotic Ring Spot. Here are some general watering practices that can make NRS worse. Watering at night, watering two times a day or more (morning & evening), watering daily are all factors that can exacerbate NRS. Please note these are general principles, we will work with you on getting your irrigation needs dialed in correctly. We recommend using the Cycle & Soak method for watering turf. Watering infrequently and longer pushes the water down to the root zone where needed and decreases evaporation and run off.
Too much nitrogen is another factor of NRS. Traditional synthetic lawn fertilization programs apply large amounts of nitrogen as the primary component in their programs. Our lawn fertilization program applies soil boosting organics with organically derived nitrogen sources to increase soil health. NRS is a soil borne fungus and boosting the soil health is crucial.
Fungicides are a wonderful tool when applied correctly to aid in suppressing Necrotic Ring Spot. We monitor soil temperatures to apply our fungicides at the appropriate times.
Ripping out all the turf in your lawn doesn’t have to be the only solution for NRS. Overseeding is another important tool for NRS. By incorporating in various grass types that are resistant to NRS and high in endophytes, we will subtly start to blend in other grasses which is less obvious than cutting out huge sections of lawn.
Mowing turf too short, mowing while grass is wet, mowing inconsistently and mowing the same direction each time can cause problems with turf. Mowing your grass at the highest mow height on the mower, mowing consistently (weekly), varying the direction mowed, sharpening mower blades often are all beneficial cultural practices.
Leaf Spot / Melting Out
Leaf spot and melting out are common diseases in turf grasses. In the past few years in Northern Colorado, we are seeing more outbreaks of Leaf Spot, mainly because of atmospheric conditions and poor cultural practices. Leaf spot symptoms, are the early stages of the disease. If left uncontrolled, the pathogen progresses into the rest of the plant to cause the melting out phase which appears as brown blades of grass and can become widespread throughout a lawn. Leaf spot symptoms initially start as small, brown or black spots or flecks on the leaf blades. As the lesions expand, the center of the lesions becomes tan with a darker brown or black border. They may also be surrounded by a yellow ring. As the lesions progress, they spread and combine to cause dieback of entire blades of grass and even plants. Melting out symptoms appear as a bronzing on a more widespread level than individual leaf spots which then leads to wilting, yellowing, and even death of the grass. Leaf Spot and Melting Out, depending on the severity, will need to be treated with multiple rounds of fungicides.
A significant spike in temperature, following a lot of rain in a short amount of time, is contributing factor that can trigger an outbreak of Ascochyta primarily in Kentucky Bluegrass. Ascochyta is different than heat stress because it can literally appear overnight. Because of all of mother nature’s moisture, people turn their sprinklers off and leave them off too long, coupled with a few days of hot and dry weather conditions contributes to an Ascochyta outbreak. Ascochyta erupts very fast and it looks like the lawn is bleached or turning to straw. This is especially noticeable after mowing, sometimes leaving stripes in the turf. It resembles drought stress but the damage is usually restricted to the leaves and the crowns and roots are not killed off. It looks like the top 1/3 of the blade of grass has been bleached.
Tips to reduce the risk of Ascochyta:
Having a balanced slower release nitrogen source in the lawn fertilization program helps instead of all quick release nitrogen in the hot summer months.
Reduce thatch and encourage moisture penetration with aeration or Liquid Dethatch.
Put mower height at highest setting during summer months
Mowing less frequently (leaving your grass taller) and sharpening your mower blade to reduce “wounding” the grass blades.
Water your lawn consistently instead of intermittently.
Follow the cycle and soak method of watering (watering longer, less frequently and in the mornings.)
According to CSU Extension, “Snow mold is a fungal disease that develops when snow falls on unfrozen turf and remains there for long periods of time.” A snow storm after warmer temperatures is when snow mold presents itself. North facing sections of lawn or shaded areas that do not get direct sunlight are typically where snow mold pops up.
We recommend removing large piles of snow by evenly distributing them to allow the snow to melt more quickly and the grass to dry out. When the grass dries the snow mold becomes cake-like and hardened. It is best to rake the grass to break the snow mold up. Spring aeration is also beneficial to break up the snow mold and allow nutrients to get to the roots. Areas affected by snow mold might take longer to green up in the spring. If the snow mold is very severe, it can kill the grass.
If a lawn consistently sustains snow mold damage annually, a fungicide treatment can help prevent snow mold from causing damage.
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