Late season potassium nitrate app & brown patch

[ArTurf]

Would an app of potassium nitrate @ 1/2 lb per K with some liquid iron promote brown patch this late in the season on St Aug? Meant to get it down earlier but things didn't work out. Temps will be in the upper 50's to mid 80's for a while.

[RAlmaroad]

Arturf:
What is the basis of your question? There's been some discussion from universities on the use of a non-sulfur based nitrogen effecting some type of fungi. However, brown patch regresses when temps get hot and shows up when temps cool off IF humidity is high. I personally put down 1lb of potassium nitrate monthly for St. Augustine along with up to 1lb of ammonium sulfate (0-0-21) with micro nutrients and iron. The last application before things start to go dormant is 1lb of 20-20-20. Of course our growing season still has about a month-6weeks before things go dormant but in reality our St. Augustine never goes totally dormant like centipede. So...you should be fine if you are just applying Potassium and Iron...check the humidity rule.

[ArTurf]

Originally Posted by RAlmaroad

Arturf:
What is the basis of your question? There's been some discussion from universities on the use of a non-sulfur based nitrogen effecting some type of fungi. However, brown patch regresses when temps get hot and shows up when temps cool off IF humidity is high. I personally put down 1lb of potassium nitrate monthly for St. Augustine along with up to 1lb of ammonium sulfate (0-0-21) with micro nutrients and iron. The last application before things start to go dormant is 1lb of 20-20-20. Of course our growing season still has about a month-6weeks before things go dormant but in reality our St. Augustine never goes totally dormant like centipede. So...you should be fine if you are just applying Potassium and Iron...check the humidity rule.

The lawns I might be putting this down on may have had brown patch in the cooler months (fall & spring) is the reason I am asking this. I know you apply pottasium nitrate like this and figured you would chime in. I just didn't want to do anything that would promote the brown patch.

[Ric]

Brown Patch is a soil borne disease that has a Fall and Spring Temperature window where it is very active. It like a high pH or alkaline or sweet condition. Non Sulfate Fertilizer help promote Brown Patch because they "SWEETEN" the soil where Sulfate Fertilizers "SOUR" the soil. Potassium will Sweeten the soil while Nitrate will help Sour it. Iron also Sours so your Mix should be just on the sour side.

Sept I start with a Preventative Fungicide as a Blanket treatment. Because my soil is more Calcareous Sand than soil, I deal with a lot of Brown Patch. It is more economical for me to apply a Preventative Fungicide than to fight Brown Patch all winter long.

Sweet = pH up

Sour = pH down

.

[ArTurf]

Originally Posted by Ric

Brown Patch is a soil borne disease that has a Fall and Spring Temperature window where it is very active. It like a high pH or alkaline or sweet condition. Non Sulfate Fertilizer help promote Brown Patch because they "SWEETEN" the soil where Sulfate Fertilizers "SOUR" the soil. Potassium will Sweeten the soil while Nitrate will help Sour it. Iron also Sours so your Mix should be just on the sour side.

Sept I start with a Preventative Fungicide as a Blanket treatment. Because my soil is more Calcareous Sand than soil, I deal with a lot of Brown Patch. It is more economical for me to apply a Preventative Fungicide than to fight Brown Patch all winter long.

Sweet = pH up

Sour = pH down

.

How many apps of preventative do you put down? If more than one, at what intervals?

[Ric]

Originally Posted by ArTurf

How many apps of preventative do you put down? If more than one, at what intervals?

First our Climates are totally different as are Our soil. What works for me might not work for you. Or because I have a Year round Growing Season and soil My treatments might be a Over Kill for you.

I do between 6 and 8 treatments on Turf a year depending on the customer. Sept I will start my preventative Fungicide because it is Traditionally Sept 15th that our nights turn to the Lower 70's. (But Not this year) Remember Brown Patch is also Heat Sensitive. While Brown Patch is present in the summer, The high canopy Temperature of Summer suppress Brown Patch. BTW Sometimes called Winter Patch and now it is called Large Patch.

To me It is more important to study the Life cycles of Pests than it is to look at chemicals. By knowing your Climate and major known pests and when they express themselves, You have the upper hand. Chemicals Come and Go, but the Life Cycles stay the same. It is the Diagnosis of the problem that is the Problem in most cases. Once your Diagnosis is correct there is Standard Protocol for treating it. I not use IPM but I do use BMP (Best Management Practices) The big difference is I treat more Preventively than IPM or I pay Materials.

.

[44DCNF]

A thin layer of peat applied as a topdressing will lower the surface ph enough to make a difference as well, ******ing it's grip on the lawn. Have you used that much Ric?

[Ric]

Originally Posted by 44DCNF

A thin layer of peat applied as a topdressing will lower the surface ph enough to make a difference as well, ******ing it's grip on the lawn. Have you used that much Ric?

fl-landscape is in my town and has the power top dressing Machine and a 33K GVW dump truck. He has posted pictures many times of that equipment. We have a couple of Horticultural Recycling center with good Compost. I recommend anyone in my area to have him top dress yards.

While I agree Peat would be a better top dressing. The cost in both Labor & Equipment to break the compressed bales of peat into spreadable material compared to it's advantage over Compost is not practical. We can not purchase lose peat in our area for less than a 40 yard truck load. Compost is sold as needed.

.

[Duekster]

Originally Posted by Ric

fl-landscape is in my town and has the power top dressing Machine and a 33K GVW dump truck. He has posted pictures many times of that equipment. We have a couple of Horticultural Recycling center with good Compost. I recommend anyone in my area to have him top dress yards.

While I agree Peat would be a better top dressing. The cost in both Labor & Equipment to break the compressed bales of peat into spreadable material compared to it's advantage over Compost is not practical. We can not purchase lose peat in our area for less than a 40 yard truck load. Compost is sold as needed.

.

But compost is not as effective as Peat on TARR. No studies on Brown Patch that I am aware.

[Ric]

Originally Posted by Duekster

But compost is not as effective as Peat on TARR. No studies on Brown Patch that I am aware.

Did I not say Peat was a better Top Dressing????


.