marcjw; i had a fungus problem (mild) around the same time last year. My game plan for this year is to apply a fungicide (granules)around the 1st week of April, hope to catch a good rain. This will coincide with some lawn green-up here in Atlanta. Spring 2019 i had the sever fungus problem however last fall I recognize it and started treatment immediately.

 

What's the preventative fungicide most folks are using now? I read here recently that propiconazole wasn't as popular anymore...

 

Yesterday I got an alert from Syngenta Greencast that soil temps in my area were approaching the 60F mark (3 day average) and that is when Rhizoctonia fungal disease (aka zoysia patch, large patch, brown patch) resumes activity.

I don't know when Green Up will happen where you are, but around here conventional wisdom would say it's still another month away. But I'm sure that 60F soil temp is going to get here before April 1st. So then "trusting the science" -or the trustworthy folks in Syngenta's marketing dept. - that leads me to think that I need to get some azoxystrobin onto my zoysia before Green Up officially or traditionally occurs. I don't think I've ever done that before, but maybe I should have.

That alert was sent out yesterday, but we're not going to cross that temp threshold today or tomorrow; the soil avg was standing at 55F and today even the air temps won't get that high. And the next 70F daytime temps are predicted to be a week away. So I've still got some time in the next 7 days to beat the oncoming threshold of 60F soil temps.

Zoysia never completely halts transport from leaf blade to below ground, unlike Bermuda. Although at this point in the season, it must be assumed that absorption and transport will be slower and less efficient than when the plant is experiencing more comfortable temps.

Azoxystrobin has bi-directional transport in turf. It can be absorbed by the roots or by the leaf and move in the plant both upwards and downwards to provide antifungal protection throughout. What doesn't get absorbed in the leaf can be absorbed by the roots and still have effect. That's a known good fungicide against Rhizoctonia, with a good chance of getting absorbed by the plant, and so I plan to fire that one first.

 

I think I got a email from Syngenta too but I didn't read it. It may be best to get a preventative down now. Curious what other zoysia owners do as well.

 

I don't have zoysia, but I do fight large patch in my St. Aug. I didn't wait until green-up. Instead, I follow the indications published here: https://www.apsnet.org/edcenter/disandpath/fungalbasidio/pdlessons/Pages/Rhizoctonia.aspx

Large Patch

Large patch occurs in the fall and spring, when warm-season turfgrasses are entering or exiting their period of winter dormancy. Infection of the lower leaf sheaths by R. solani occurs whenever the temperature of the thatch layer is between 10ºC (50ºF) and 21ºC (69.8ºF), and continuous moisture is available for at least 48 hours. Warm-season grasses are not growing vigorously during the spring and fall, and are highly susceptible to pathogen attack. Patches may also develop in the summer during periods of cool weather, especially in wet or shaded sites.

Recent evidence indicates that the majority of large patch development occurs in the fall. Symptoms are observed in the spring because plants infected the previous fall have not yet recovered. As conditions become optimal for the growth of warm-season turfgrasses in late spring/early summer, recovery occurs due to the spreading growth habit of these grasses.

Excessive moisture levels in the soil, thatch, and lower turf canopy encourage large patch development. Factors such as poor drainage, shade, restricted air movement, or excessive irrigation increase the severity of this disease.

 

Thanks for the info everyone. I think I'll get an application down this weekend.