Alternative controls for dollar spot

Kentucky bluegrass, Fescue, Rye and Bent, etc
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HoosierLawnGnome
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Alternative controls for dollar spot

Post by HoosierLawnGnome » June 27th, 2019, 2:14 pm

A grad student is conducting some cool experiments on controlling dollar spot with ferrous sulfate

https://twitter.com/GuelphTurf/status/1 ... 95488?s=19

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Re: Alternative controls for dollar spot

Post by Green » July 1st, 2019, 7:16 pm

Cool. Am I right that the damage from it is worse in very low mowing height situations like a putting green? I just have a bunch of brown blades/spots, but I mow between 3 and 4 inches in this weather.

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Re: Alternative controls for dollar spot

Post by Cole » July 2nd, 2019, 3:07 pm

Interesting timing since I just made a post about a few spots you thought were potentially early indicators of dollar spot. The only thing that the lawn has received is milorganite and a lot of rain. If I understand correctly, milorganite's iron is ferrous sulfate? The spots seem to be disappearing if not completely gone. I applied the milorganite about 2 weeks ago.

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andy10917
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Re: Alternative controls for dollar spot

Post by andy10917 » July 2nd, 2019, 3:33 pm

Milorganite is a natural product derived from the Milwaukee Sewer District. The Iron found in it is what Iron was ingested by the single-cell organisms that digest the incoming waste stream. It's more complicated than an inorganic product like Ferrous Sulfate, but that is good news - the biological (organic) forms of Iron do not react with other inorganic compounds in the soil anywhere near as quickly as things like Ferrous Sulfate, meaning that they remain available to plants/grass longer. This is actually a form of "natural chelation" without the chelated Iron cost. While Ferrous Sulfate almost immediately becomes unavailable to plants at pH levels of 7.1 or so, Iron can remain available often to pH values of 7.6 - 7.7, and I've seen cases of it working up above pH 8.0. This is why we don't tell people with higher pH values to use Ferrous Sulfate - it doesn't work. Milorganite doesn't have any magic in their processing - products like Bay State Fertilizer (also from biosolids) also work the same way - but the amount of the Iron is totally dependent on the amount of Iron in the incoming waste stream's Iron content.

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Re: Alternative controls for dollar spot

Post by HoosierLawnGnome » July 3rd, 2019, 4:28 pm

Cole wrote:
July 2nd, 2019, 3:07 pm
Interesting timing since I just made a post about a few spots you thought were potentially early indicators of dollar spot. The only thing that the lawn has received is milorganite and a lot of rain. If I understand correctly, milorganite's iron is ferrous sulfate? The spots seem to be disappearing if not completely gone. I applied the milorganite about 2 weeks ago.
Like Andy said, different form of iron, different action.

IF you had dollar spot, one way to treat it is to boost N.
N doesnt kill the $spot, it helps a plant outgrow and survive it. Milorganite would be one way to supply Nitrogen.

But that doesnt mean the milorganite is killing the $spot pathogen by applying iron, which is what this experiment is investigating.

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