The face I make when I see a possible disease in my lawn.
There is a yellow patch in my lawn. Is it a disease!? Is everything dying!?
Let’s start with a reminder that not everything weird in your lawn is a disease.
With the consistently hot and humid weather we have been having, conditions are perfect for diseases to run amuck. However, not all lawn stress or damage is a disease. Sometimes, it can be tricky telling a disease apart from physical damage.
For example, can you tell which of the “diseases” above are diseases and should be treated with a fungicide? SPOILER ALERT: The answer is none of them.
Each of these eight photos is the result of physical damage to the lawn. From left to right the top row is: fertilizer striping, dog damage, compaction, and fertilizer striping. The second row (from left to right) is salt or chemical runoff, malfunctioning irrigation heads, bug spray, and soil compaction.
But what about real diseases!?
I know what you are thinking. You are thinking, Sarah, why on earth are you starting a blog about lawn diseases with a mini-lecture that not everything is a disease?
The short answer is: because science.
The long answer is: It is important to get weird symptoms in your lawn diagnosed before you immediately jump to fungicide use. Unnecessary uses of fungicides will ultimately promote resistant strains of diseases in the same way that taking unnecessary antibiotics promotes stronger bugs in our systems. Think of fungicide use like taking an antibiotic; you really should only use them when you are sick.
This leads me to my first piece of advice when you see something strange on your neighborhood lawns. Don’t panic.
Summer patch
Really look at the area and ask yourself if what you are seeing might be from obvious physical damage, like mowing when it is hot. (Read here for more info on summer care tips.) Do you see any straight lines? That is a giveaway that what you are looking at is definitely not a disease (since Mother Nature never follows fence lines or straight lines).
Necrotic Ring Spot
Still not sure what you are looking at? Take photos and then look at them again in a week. Is the damage in the exact same spot? That might be a hint that there is something physically wrong with the space, such as compaction or drought stress, that is not a disease. Physical issues tend to be easily remedied by 13-13-13 and routine core aerations each year. Is it super hot and dry outside? That is a VERY strong possibility the damage you are seeing might be sun scorch, which is just a result of the plants burning up from intense heat in the peak of summer. To avoid this, check your irrigation schedule and make sure the lawn is getting 1” of water per week.
Pythium blight
Are things still looking wonky?
Then it might be a disease.
This year, we have been seeing some photos come in of disease activity on peoples’ lawns. Consistently hot, humid, and rainy days can be a playground for fungi that result in diseases like summer patches, necrotic ring spot, and pythium blight. In our area, diseases like summer patches tend to be more commonly found in tall fescue or blended species lawns, while bluegrasses might show diseases like necrotic ring spot.
Bonus Tip: Rust
This is a juvenile disease that should not be treated with a fungicide in most cases. Use 13-13-13 instead!
We do carry a fungicide that would treat each of these diseases (and others like dollar spot as well). However, it is important that we do a positive ID on the disease first because our instructions for application rates and timing will be different depending on the disease. So here is what we would like you to do:
Don’t panic. Take pictures (both close up and far away) of the area of concern.
Email them to us at info@bgsod.com. Be sure to include your phone number in the email, along with any other information that would be helpful for Sarah to know, such as when the disease appeared, what kind of species of grass you have in your lawn, what side of the house it is active on, what you have done to feed/care for your lawn so far this season, etc.
Follow our instructions. I know this sounds crazy, but treating a lawn disease really is like treating an infection in your body; it is important to follow our instructions closely and not deviate from what you were told.
Keep in mind that if we have you apply a fungicide, we will have you follow up soon after with a feeding of 13-13-13. This is because fungicides kill both good and bad bacteria in the soil, so we are trying to jumpstart healthy growth in the area again after the disease has been controlled. Think of this like being good about taking a multivitamin again after being such for a few weeks. We are just trying to make sure the plants have everything they need to continue to fight the disease on their own while speeding recovery.
A special note about rust: Rust is also on the way for juvenile lawns in August. We do not typically recommend using a fungicide for rust. Rather, feeding the lawn with 13-13-13 will help the plants grow out of this minor disease faster. For more information read this article.
Preventing Disease
The best defense is a good offense, right? Many bad bacteria for lawns thrive in yard conditions that are hot, wet, and lacking in nutrient balances that would help fight off the disease. We obviously can’t do much about the summer temperatures here in Iowa, but we can work to prevent many outbreaks simply by improving drainage in the affected area (aeration, tiling, etc.) and feeding our lawns correctly.
Pro Tip: Avoid using fungicides annually as a “preventative”. Think of putting down an unnecessary fungicide like taking an antibiotic unnecessarily - it doesn’t really help anything and it actually creates a heightened risk of resistant bacteria for the future. Instead, focus on good cultural practices while mowing, watering and feeding that will promote disease resistance in your lawn. And perhaps most importantly of all, no matter what happens remember you can call Blue Grass (319) 842-2165 … and don’t panic.
Bonus Tip: Mushrooms
As long as we are talking about fungi, we have to mention mushrooms.
Believe it or not, mushrooms are a good thing. They are a sign of healthy bacteria in your lawn breaking down old organic materials like old stumps. Don’t worry about them and don’t spray them. If they are unsightly to you or you fear touching them, simply mow them down. They will come and go on their own as weather conditions evolve each summer. Don’t panic!