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May 30, 2018 | Lawn Care Tips, Lawn Guides

Treating Dollar Spot Fungus in Lawn

Treating Dollar Spot Fungus in Lawn

The Dollar Spot caused by the lawn fungus is a fairly common disease, especially on golf courses sown by the bentgrass or Poa annua. It got its original name more than 70 years ago when it was discovered that the infected places on the lawn resemble silver dollars in shape.

Currently, the dollar spot is the ideal name for the disease, the fight against which costs golf clubs a lot of money. Golf clubs are increasingly dealing with budget constraints so reducing the frequency of the curative (fungicide) application to combat the dollar spot is a good possibility of saving without significantly affecting the playing quality of the field.

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About the dollar spot fungicide

The Dollar Spot is common on the lawns and golf courses of the Midwest and the northeastern United States for most of the growing season, while many other diseases manifest themselves in more specific environmental conditions. The long duration of seasonal activity requires managers to envisage the implementation of a program aimed at the prevention of a dollar spot in the budget. Some specialists carry out 5 to 10 (or more) fungicide infusions on the fairways annually. The number of insertions to prevent the onset of this disease on the fairways depends on many factors. One of them, and, as a rule, the main one, is the frequency of manifestation of the disease in your field.

Why does dollar spot appear on the law?

What do the spots appear on the lawn? How to get rid of them? In the care of the lawn, these questions necessarily arise sooner or later. It is quite simple to restore decorativeness in any of these cases – you just need to identify the nature of the problem and eliminate its causes.

The fact that the lawn has lost its green color and spots appeared on it usually is the result of a violation of the rules of watering and cuts. But what if the spots keep occurring despite all the instructions? Probably, the lawn was attacked by pests or diseases. Fortunately, methods of combating most of the lawn diseases have long been developed and successfully implemented. But in order for the treatment to be effective, it is necessary to determine what the real cause of the dollar spot is.

Dollar spot is a disease of parterre lawn. Festuca rubra is the most defenseless before the disease. Small spots, similar to the silver dollar, first appear on the grass. Delay in treatment leads to the merging of these formations into untidy islets. Help the lawn by spraying it with Carbendazim. You can prevent silver dollar fungus by following these preventive measures:

  • Aeration
  • Verticalization (piercing the lawn)
  • Spring application of nitrogen fertilizers

The main cause of the disease is fungus. It survives over winter holding to the plant matter in the thatch layer. It also sticks to the plant matter in the soil. In winter, the fungus doesn’t really grow, but when it becomes warmer in spring the growing process starts and the components of the fungus – mycelium and fruiting body – start to grow.

Dollar Spot Treatment

Conditions that lead to the appearance of the fungus

The growth of the fungus is caused by certain environmental conditions, which include:

  • Lack of moisture in the soil – dollar spot will flourish in lawns that aren’t properly watered. A low moisture level of the soils will lead to the occurrence of dollar spot on Augustine grass. The grass affected by the disease dies.
  • Too much straw in the soil – dry grass prevents the water to penetrate the soil and create good conditions for the disease to survive.
  • Not enough nitrogen – nitrogen is required for the leaf grow. Adequate levels of nitrogen in the soil will result in vigorous lawn that will be resistant to any disease.

It is noteworthy that the signs of the disease manifest themselves in different ways depending on the weather conditions. When the air temperature is above + 25C, the plants produce impressive spots from light yellow to dark brown. At cooling, the size of spots is much less, and leaves of grass get yellow-orange coloring. Simultaneously with the change in color, the root system dies. On plants, you can see all the components of the fungus.

The disease affects weakened less nutritious grass. The risk factors include too short trimming, excess or lack of moisture.

The best dollar spot disease treatment

At the first signs of the disease, it is necessary to increase watering and maximize nitrogen fertilizing. Good results are obtained by the use of fungicides. Correctly selected complex fertilizers are recognized as the best prevention of this disease

The fight against the dollar spot with agrotechnical and chemical measures is never ideal, and despite regular preventive measures, there are outbreaks of the disease several times during the year. How often does the dollar spot appear on your lawn? How long is the disease life cycle?

Dollar Spot Disease Life Cycle

Before answering these questions, it is necessary to assess the degree of the impact of the disease on the lawn. The pathogen of dollar spot destroys the leaves, contributing to the appearance of light brown spots on the bentgrass lawn with a diameter of 1–2 inches.

Since the disease does not affect the roots of the lawn, it is mainly a cosmetic problem and, as a rule, is not fatal for the lawn. During the disease, on the surface of the lawn, there may be small hollows, often referred to as pitting. The grass on the infected lawn will be discolored, tangled.

Here is the instruction on when to apply fungicide and how to treat the disease:

  • The grass affected by dollar spot will die quickly if left untreated. Therefore, it is necessary to urgently treat the affected areas with fungicides and mow the lawn as often as possible. To avoid illness, it is necessary to feed the lawn in spring and summer with complex fertilizers and use phosphorus-potassium fertilizers in autumn in addition to nitrogen fertilizers.
  • In late spring or early autumn, it is necessary to immediately treat the affected areas with a systemic fungicide. In the future, pay attention to preventive measures such as aeration, scarification, and fertilizing. It is important to ensure that the trimming is not too short.
  • Lime the soil before sowing the herbs.
  • Make phosphoric fertilizing.
  • Do not exceed the norm of nitrogen fertilizers.

Tips on how to treat dollar spot on turf

The main methods of treatment include:

  • Increasing nitrogen levels
  • Balancing the nutrition of the lawn (to make potassium in the summer period)
  • Fight with felt
  • Regularly mow grass at an optimal height
  • Remove morning dew regularly
  • Maintain the wet zone of the root system and the positive water balance of the plant
  • Improve air movement (aeration)

In order to prevent many fungal diseases of the lawn, plants should have optimal soil conditions. Get healthy inoculum. A preventive measure for dollar spot control is regular care of the lawn and a uniform spring and autumn fertilization. Do not forget about the proper height when mowing grass and removing the lawn’s remains from the surface of the lawn, in which fungus usually multiplies.

Equally important are regular watering, spring aeration of old lawns growing on heavy soils, and chinked sod. At the first signs of the disease, measure the acidity of the soil, which under normal conditions fluctuates within pH 6.5–7.2. With reduced acidity in spring, add algal limestone (50–70g/m2) to the soil. The increased acidity of the soil is neutralized by superphosphate or potassium sulfate (20g/m2).

Brown spots on the surface are the result of pests (long-legged, wireworm, and scoop). If the dead grass is easily extracted from the soil, then the reason for sure is in the appearance of pests. Yellow or brown spots on the surface of the green grass are the result of local burning out of a large and unevenly distributed dose of fertilizer or urea. Such places should be often and abundantly watered to accelerate the leaching of harmful substances from the soil.

What should you do if your lawn gets sick?

If you see dollar patch on lawn, do not walk on the lawn affected with fungus so as not to transfer spores to other sites. Protect the affected area of the lawn. On the surface affected by the fungus scatter and distribute the compost. Try to restrain the spread of the disease.

Spray the affected areas and the adjacent places with a fungicide that inhibits the development of fungal spores. In autumn, cover the bare areas of the lawn with the grass. Use only disease-resistant lawn grass mixtures. The disease can be prevented by ventilating the lawn on average every three to five years to provide oxygen to the soil and plant roots. Plant the lawn every five years with new grass mixtures to increase its disease resistance. The height of mowing depends on the type of grass mixture and varies from 3 to 5 cm. Remove the remnants of mown grass.