It's That Time of Year...
By Todd Hicks
Well, the 2025 turf season is here. Turf managers are out trying to catch up with turf maintenance to prepare their turf for whatever this year’s weather brings us. I hate to bring up bad memories but looking back at what we went through in 2024, here are the diseases I would be on the lookout for this year.
The first problem that sticks out from last year was the excessive amount of leaf spot we encountered and its season long duration (Drechsler & Bipolaris spp.). This problem effects both short and high cut turf managers and is not prejudice as to what species of turfgrass it affects.
Last year we saw widespread thinning of turf no matter where we were or what type of turf we were looking at. The problem was compounded by the fact that leaf spot likes both warm and cold weather patterns, it just needs wet weather. This disease is also a great chameleon, its patterns seen on the turf can mimic other diseases quite well. If in doubt when diagnosing your problem, always seek help. Whatever chemistry has been working for you in the past fighting leaf spot should be fine again this year.
The second disease I would be concerned about this year is Dollar Spot. Dollar spot can affect most of our grass species and is a major concern for turf managers in the Midwest and northeast. The disease can be brought on in the spring and fall by nighttime temperatures around 60-65 F and daytime temperatures of 75-85 F. High relative humidity mornings (70%-80%) heavy dew provide the right environment for infection. Stressed turf, which is managed under poor fertility can also lead to dollar spot outbreaks. Slow growing turf from other environmental and/or management practices can increase severity. Dollar spot is easily identified by the round spots that are tan in color. Dollar spot on greens can range in size from small flecks to silver dollar sized areas that under sever conditions will grow together to form larger patches. On fairways or high cut turf the individual spots may be larger, 1-2 inches in diameter.
The best way to fight this disease is to make sure you have a sound fungicide program that targets dollar spot in the spring and again in the fall. Make sure you’re covering all your bases culturally also. This means things like adequate fertility and knocking off morning dew. We are firm believers of the early spring spray program. This is putting out an early application for the disease long before it shows up. In theory this pushes the inoculum level down when it’s weak causing the disease to show up later and in a weaker state. This puts the turf manager ahead of the disease and if a breakthrough happens, the disease pressure is kept low and manageable. When the weather and time of year are just right for that heavy break out of disease take a careful look at your fungicide labels for recommended application intervals and rates. This is not the time to be stretching out dates for your fungicide coverage on dollar spot. High disease pressure may require shorter intervals and higher rates between applications. The disease tables and footnotes of these labels can contain important information regarding the rates and timing intervals.
The last big threat on my list for this year is Anthracnose. Turf managers that deal anthracnose, especially anthracnose on Poa annua, need to be extra diligent this year. With all the stress factors so far this year on Poa expect this disease to be a bit more significant than last year. Again, preventative spraying keeps this problem at bay and is the best way of heading off this problem. There is an information sheet about Anthracnose Basal Rot on greens, key management tools and fungicides on the web site under the “handouts” tab at the top of the page; turfdisease.osu.edu
The final disease to cover is Brown Patch. With our current weather pattern, many out there managing turf type tall fescue have already been experiencing this disease. Brown Patch (Rhizoctonia solani) is a disease that favors hot, wet and humid environments. Day time temperatures fall in the mid 80’s to well into the 90’s, with nighttime temperatures in the high 60’s to mid-70’s, also under very humid conditions. This disease favors areas that hold moisture or low spots that do not drain well. This disease also keys on turf that is managed under high fertility. Management strategies include avoiding excessive watering and fertility, dew removal and fungicide applications. Brown patch can sometimes be confused with foliar pythium, both have a thick white mycelium. If you’re not sure which one of these diseases you have a helpful trick is to apply a strobilurin fungicide, they work well on both diseases!
If you’re not already, you might want to start a phosphite program. This group of fungicides is our only true systemics, provides some disease control, and provides agronomic “benefits” for your turf. None of us are sure what the rest of our summer weather is going to bring. I’m a “glass is half empty” kind of guy so I would do as much as possible now to get ahead of disease and stress on my turf while I still had the opportunity.
