The past month has been very wet with a bit of heat mixed in for just the right amount of stress on weakened lawns. Wet weather means your lawn is more likely to contract common diseases due to high moisture and humidity caused by rain or drizzle. Leaf spot to a lawn is like having a common cold to humans. Most lawns get leaf spot but it passes without much fanfare with the onset of summer and warmer weather. There are occasions when leaf spot can manifest into a more serious stage, sort of like getting pneumonia from a cold. This stage is called “melt-out” and is the result of a significant infection, large enough to cause damage to the growing point of the turf plant, the crown. A weakened crown is susceptible to injury and plant decline, or even death, depending upon the weather.
The pictures in this blog post were taken from a lawn infected with leaf spot disease. A lawn full of leaf spot collapses under stress such as a warm day and is visible as brown sunken patches or uneven color in the lawn. One picture is an overview shot of the lawn and how it looks unhealthy given leaf spot infection. The second picture illustrates what the infected leaf blades look like up close – yellow and black lesions or spots surrounded by collapsed grass plants which have succumbed to the later stage known as “melt out”.
The best course of action is not to mow short as this process will enhance the likelihood of the disease reaching the crown and causing damage. Mow at 3” and you can remove the clippings in this scenario if needed. Try to cut the lawn while dry and apply a slow release fertilizer with no herbicides so that the grass is not root pruned and stressed to a great degree. Your lawn must “outgrow” this situation and a gentle touch is required. For serious infections, the use of fungicides, similar to those we use for athletes foot should be considered and used to help retard and slow the life cycle of leaf spot disease.
A healthy lawn is less susceptible to this type of disease as are certain grass varieties. If your lawn does not look right, then call your lawn care professional today and get the help you need, be it advice or some other warranted treatment.