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Early-Season Programs for Dollar Spot Control

Early-season dollar spot control was mentioned in a previous post by Dr. Kaminski. Basically fungicides are applied long before symptoms develop in the field, which results in a significant delay in the onset of symptoms. The proposed theory behind early-season applications is they reduce the pool of initial inoculum of the dollar spot fungus enough to slow progression of the disease. A single early-season application will not provide season long control in the Midwest and it seems frivolous to employ an early-season treatment without changing the conventional fungicide program.

Therefore we are currently examining two different season long programs coupled with early-season applications to see if we can save fungicide applications. This experiment is being conducted at the OJ Noer Turfgrass Research and Education Center and at Milwaukee Country Club. We know from previous research that DMI's seem to slow disease progression the most in Wisconsin. We also know that chlorothalonil and vincozolin did not have any early-season activity in our trials, sorry John :).

Our approach was to make several different early-season applications when soil temperatures were between 55 and 60 F, which usually equates to May 1 in southern Wisconsin. Then we initiated follow up applications of a Banner Maxx tank mixed with Daconil Weatherstik (1 fl oz and 2 fl oz, respectively) every 21 days or Banner Maxx tank mixed with Daconil Weatherstil (1.5 fl oz and 3 fl oz respecitively) every 28 days. We included a non-treated control and a conventional spray program (Banner/Daconil 1.5 fl oz and 3 fl oz) that started on June 1st and continued on a 14 day interval. Next year we are going to include a conventional treatment sprayed on a 21 day interval. The aim of the project is to limit fungicide applications and/or the amount of active ingredient deployed while still maintaining adequate disease control.

In the interest of simplicity I have only presented four treatments: non-treated control, Early-season with 21 day follow-up (Banner Maxx early-season app.), Early-season (Banner Maxx) with 28 day follow-up and the conventional program. We had excellent dollar spot pressure at the OJ Noer this year as documented in the non-treated control plots. Plots receiving follow-up applications every 21 days at reduced rates reduced dollar spot severity compared to the non-treated control, but not to levels that would satisfy a golf course superintendent. The early-season with a 28 day follow-up worked almost as well as the conventional program.

Employing an early-season application for dollar spot followed up every 28 days with Banner/Daconil can save at least 2 fungicide applications when compared to a 14 day conventional program. Currently we are gathering budget numbers from 4 different golf courses to help us determine the economic benefit of these results. This work will continue next year, so please stay tuned. Also any comments or advice would be greatly appreciated!

As far as disease activity, the only disease I have seen this week in the field is rust. Dollar spot flared over the weekend, but nothing else has been reported or come through the TDL.

2 Responses to “Early-Season Programs for Dollar Spot Control”

Anonymous said...

Hi, I am just curious as to what the data looked like on 8/6/09. That date puts us a little closer to the last spray of the 21 and 28 day programs and really tests the 14 day conventional program.


Jim said...


The data on 8/6/09 is similar to the data I presented in the post. I choose this particular data because we had a flush of dollar spot activity the weekend and into the early part of the week.

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