I have a lawn disease that is spreading and I need help with properly treating it. - Ask Extension
We have had this lawn disease for a couple of summers/years. It was dx as necrotic ring spot NRS (Frog's eye) by our lawn service guys. We treated it ...
Knowledgebase
I have a lawn disease that is spreading and I need help with properly treating it. #890088
Asked November 20, 2024, 1:50 PM EST
We have had this lawn disease for a couple of summers/years. It was dx as necrotic ring spot NRS (Frog's eye) by our lawn service guys. We treated it will PillarG 2 summers ago as directed, and this past summer with lawn fungus tx purchased at Home Depot (list of diseases treated included NRS) two times as directed. The tx obviously is not working and the spots are spreading throughout our lawn. I need help in figuring out what to do to properly tx this disease so it doesn't take over and ruin our entire lawn. Can you please help us? I was only able to upload 1 pic due to the mb size of the photos. I would be happy to send more if needed.
Charlevoix County Michigan
Expert Response
Looking your photo over I don't identify any obvious signs of NRS but it's also late in the growing season so there probably isn't much to be seen.
When did you last do a soil test? The first step to having a healthy good looking lawn is doing a soil test this fall and then every 2-3 years. You will learn about your soil including soil type, pH, nutrient levels and more. Knowing the type and fertility of your soil is the starting point to establishing & maintaining a strong turf that can resist diseases, moss, weeds, insects/grubs and look great at an optimal cost. More info here: Don't Guess-Soil Test-MSU and MSU Home Soil Test-self mailer
Necrotic Ring Spot presents itself as light green to yellow matted patches 3-24 inches across or rings w/ green turf or weeds in the center. The roots and rhizomes are blackened and plants are easily removed from the soil. Conditions for NRS include 50F-75F temps and wet weather. Stress, compaction, drought and temps above 80F enhance symptoms. Excessive nitrogen (N) applications (fast release type, more than 0.5# per 1000SF per application) can increase severity.
Links to information on necrotic ring spot and its control:
https://www.canr.msu.edu/ipm/diseases/necrotic-ring-spot - curative and preventive fungicide info
http://plantclinic.cornell.edu/factsheets/necroticringspot.pdf - fertilizing & mowing recommendations + fungicide table
https://www.extension.purdue.edu/extmedia/BP/BP-116-W.pdf
https://extension.illinois.edu/plant-problems/summer-patch-and-necrotic-ring-spot
Do the soil test this fall. Implement soil test recommendations starting in the spring. Be prepared to apply preventive fungicide(s) in the spring as well.
When did you last do a soil test? The first step to having a healthy good looking lawn is doing a soil test this fall and then every 2-3 years. You will learn about your soil including soil type, pH, nutrient levels and more. Knowing the type and fertility of your soil is the starting point to establishing & maintaining a strong turf that can resist diseases, moss, weeds, insects/grubs and look great at an optimal cost. More info here: Don't Guess-Soil Test-MSU and MSU Home Soil Test-self mailer
Necrotic Ring Spot presents itself as light green to yellow matted patches 3-24 inches across or rings w/ green turf or weeds in the center. The roots and rhizomes are blackened and plants are easily removed from the soil. Conditions for NRS include 50F-75F temps and wet weather. Stress, compaction, drought and temps above 80F enhance symptoms. Excessive nitrogen (N) applications (fast release type, more than 0.5# per 1000SF per application) can increase severity.
Links to information on necrotic ring spot and its control:
https://www.canr.msu.edu/ipm/diseases/necrotic-ring-spot - curative and preventive fungicide info
http://plantclinic.cornell.edu/factsheets/necroticringspot.pdf - fertilizing & mowing recommendations + fungicide table
https://www.extension.purdue.edu/extmedia/BP/BP-116-W.pdf
https://extension.illinois.edu/plant-problems/summer-patch-and-necrotic-ring-spot
Do the soil test this fall. Implement soil test recommendations starting in the spring. Be prepared to apply preventive fungicide(s) in the spring as well.
