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woodbelly

Help identify fungus on new lawn - possibly pythium blight

woodbelly
10 years ago

I'm looking for help identifying what I believe is a lawn fungus in the attached pictures. This is a new lawn of perennial rygrass from hydroseed in late April. The hydroseed was laid over 3" in loam over roughly 20k sq. ft. The problem started showing up in mid-June and has spread around the new lawn but stayed away from the center where it receives full sun. The rest of the lawn all receives partial sun throughout the day because of some very tall oaks around the perimeter.

I've been watering for ~1hr each morning before sunrise except on days with rain in the forecast.

About 5 weeks ago I applied Vigoro Fertilizer 29-0-4. The following week the lawn looked its best (I assume thanks to all that N) but its been downhill since. I noticed what I thought might be a fungus in a couple of isolated areas about 3-4 weeks ago and immediately applied Scotts Fungus Control granules at the "prevention" rate and covered roughly 15,000 sq. ft of the yard. Since germinating I've mowed the grass 6 times and I always bag it and wash the mower deck when done. I appreciate any suggestions or comments you have. TIA!

In the last photo I raked away the dead grass and some living grass along with it. Nothing but dirt underneath.
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Comments (4)

  • tiemco
    10 years ago

    From your pictures, it certainly could be pythium, especially on a spring seeded stand of grass. You are watering too much, which can lead to fungal issues, especially pythium since it is a soil pathogen. The watering will also help spread the disease. Daily watering is not recommended for home lawns. The fungicide you used isn't effective against pythium. There are several on the market. Heritage is a very good one, and they usually carry it at John Deere Landscapes.

  • dchall_san_antonio
    10 years ago

    Read the label on any fungicides you use. Read especially the part about the temperature for application. In MA it would seem like any time would be fine, but you don't want to do it on the one day of the year when it was too hot.

    You should be able to water one day per week and maybe one day every 2 weeks up there. With one hour per day I am surprised you have any grass left at all. Put out several cat food cans to measure the output of your sprinklers. Over the years we have worked out that one inch per week is a maximum requirement for 95% of homes in the US. Exceptions are the desert area west of Junction, TX, east of Indio, CA and south of St George, UT. Fortunately that only affects about 200 people (snicker snicker). If your temps are from 80 to 90, then you should be able to get away with watering every 2 weeks. All this depends on humidity, wind, shade/sun, clouds, soil type, soil depth, grass type, grass height, density, etc. It is much easier to watch the grass for signs of getting dry and then water. Eventually you will work out a schedule that works for your combination of factors listed above. During a normal summer for my house in San Antonio I water 3 hours once per week. During the extreme droughts we've had there will be about 4 weeks where I have to jump up to 7 hours per week, but I still do it all at one time. In the stinking hot desert with sand soil, they might have to go to watering once every 4-5 days.

  • maplerbirch
    10 years ago

    The fertilizer and excess moisture gives the pathogenic fungi exactly what they love, wet, succulent, fast growing sources of food.
    After drying it out I would also stop bagging and begin to mulch mow to help build the soil. :)

  • edbyrnes
    10 years ago

    Could this be the phythium? The grass grows in large irregular and round patches, the grass is dense with very short roots.