Late season potassium nitrate app & brown patch

Discussion in 'Fertilizer Application' started by ArTurf, Sep 28, 2012.

  1. ArTurf

    ArTurf LawnSite Gold Member
    Male, from Ark
    Posts: 3,437

    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.
     
  2. RAlmaroad

    RAlmaroad LawnSite Silver Member
    from SC
    Posts: 2,185

    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.
     
  3. ArTurf

    ArTurf LawnSite Gold Member
    Male, from Ark
    Posts: 3,437

    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.
     
  4. Ric

    Ric LawnSite Fanatic
    Posts: 11,956

    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

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  5. 44DCNF

    44DCNF LawnSite Bronze Member
    Posts: 1,460

    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?
     
  6. Ric

    Ric LawnSite Fanatic
    Posts: 11,956

    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.

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  7. Duekster

    Duekster LawnSite Fanatic
    from DFW, TX
    Posts: 7,961

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

    RAlmaroad LawnSite Silver Member
    from SC
    Posts: 2,185

    With a preventive measure in mind, this summer I started dusting some trouble spots with wettable sulfur. Greendoctor was telling me of a case about this and got me to thinking. Well the sulfur began to clear up the fungus. Since then, I apply a little with the fertilizer; as the wettable stuff will not agitate unless agitation is more like a waterfall. Also check the pH of water and adding a little vinegar to get the pH about 6.5 did well. The wettable sulfur is actually sold by Bonide as a fungicide. We have very high pH and keeping it down is a constant battle. With all of this in mind, putting the flake sulfur down two times a year when the sun can warm it will do wonders, but as mentioned--it's a constant battle. But as Ric said--preventive is a lot cheaper than the curative. I still put down two treatment at the high rate, 10 days apart in the fall and spring.
     
  9. Ric

    Ric LawnSite Fanatic
    Posts: 11,956

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


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  10. 44DCNF

    44DCNF LawnSite Bronze Member
    Posts: 1,460

    Good point Ric. Something I hadn't considered. Wondering could it be run through a hydroseeder?
     

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