Skip to main content

Dollar Spot Approach


Summer has finally arrived and the long wet Fusarium filled spring is gone! Thank God!

Anyway with the warmer drier weather comes the threat of Dollar Spot. The past two summers around the middle of  July we got hit hard with dollar spot. It came overnight and it was very widespread and required a fungicide application to keep it under control.

This year we have changed our approach to managing for dollar spot in a number of ways.

Fertility: Last year we were on a brand name fertility program. While the turf looked good I wasn't too impressed with the overall health of the turf. It seemed that I was spraying more often than not and the turf was just sick. This year I completely redesigned my fertility program specifically for disease prevention. This summer my plan is simple. Light and frequent applications of urea through my sprayer. Urea is a readily available form of nitrogen and when applied in light doses you reduce the risk of leaching and volatizational losses. I feel that a GOOD constant supply of nitrogen is critical to managing dollar spot. What I have found is that N can almost be used as a fungicide for dollar spot control. Don't mess around with the snake oils, use what works. Urea works.

My fairways also got destroyed last season from dollar spot. The reason I think they were so badly infected was that my nitrogen source was sulphur coated urea (SCU). We typically applied it every two months but last June was extremely wet and most if not all of the SCU was released too quickly and therefore the turf was experiencing a nitrogen deficiency in July. This year we have switched to a 100% UMAXX product.. This product is a more stable slow release form of urea and so far has delivered outstanding results. Again, a slow consistent nitrogen feed is what I feel is key to managing dollar spot.

Cultural: It's no secret that I might roll a lot. My approach going into dollar spot season is to try and maintain the 2x daily lightweight rolling on my putting greens. Rolling has been shown to significantly reduce the incidence of the dollar spot fungus in a number of studies. They found that rolling increased the beneficial bacteria levels in the soil. These bacterial are not good news if you are dollar spot, fusarium, anthracnose, or pythium.

So far my management plan for dollar spot control is basically pesticide free. I have left a few areas on course to see if I can in fact control dollar spot without the use of pesticides whether it be synthetic or organic. Either way I don't like applying stuff if I don't have to.

While I am very confident in my dollar spot management plan I'm not 100% confident. For this reason I am using a few other tools to make sure I don't get nuked with disease this summer.

Typical dollar spot infection in Poa annua.
"Organic" Pesticides: I have decided to go with 3 different organic products this year just to see how they perform. I know that propiconazole works. There's no need to test that.

This year I am going  to put out Civitas, Phosphites, and Rhapsody ASO. These three products show great potential and I am cautiously  optimistic that they might just be the ticket.

The great thing I like about Civitas is its mode of action. It has no effect on the fungus but arms the plant's natural defenses for disease attack. This leaves little room for resistance issues and is very safe to use. It is a certified organic product. What I don't like about Civitas is the colour of the harmonizer. For this reason I am applying it at 1/4 rates every week to keep the offensively green colour to a minimum.

Potassium Phosphite is a regular part of my greens fertility program and should also help with any disease pressures that I might face this summer. I am still searching for a phosphite product that bears the Organic Materials Review Institute (OMRI) designation so if you know of one let me know.

A product that is completely new to me is Rhapsody ASO. The way I understand the product is that it is a bacteria that fights fungus. It is one of the same bacteria that's population is increased from lightweight rolling.  I am planning on applying this product weekly in my tank mix for the next month or two depending on my control plot disease pressures.

I am of course going to leave some control plots to see if I can get away without applying these products as they are costly. And before you accuse me of going against my no preventative fungicide ideals consider this. I am leaving control plots to learn from my applications. I am also unfamiliar with these products and their efficacy.  I want to see if I can make the "organic" option work. For this to happen I have to start "all in". From there I can learn and pull back after I better understand how effective these products work. Remember, this isn't propiconazole or chlorothalonil here.

And before everyone accuses me of being anti synthetic chemicals please understand this. I am doing this not because I feel that synthetic pesticides are bad. They are great effective tools for managing turf grass pests. I am simply curious and up for the challenge to see if I can make the newer alternative organic treatments work for me on my course. I am sharing this in hopes that others will also share their experiences and management tactics for the upcoming dollar spot season. Go ahead, hate me for it!


Labels:

Popular posts from this blog

Turfgrass speedo is still my most important tool for managing turf growth after 4 years.

It wasn't the easiest year for growing grass , but the conditions were still pretty good. Almost 4 years ago exactly, I came up with the idea of comparing actual clipping yields to the "ideal" clipping yield or the clipping yield adjusted using the Growth Potential Model . Since then, it has proved to be a much more useful tool to manage growth than I originally thought .  It has been almost a decade since I started making observations on plant health and playability and how it relates to the clipping yield. I have been constantly searching for ways to get the growth rate right as often as I can and this tool seems to be the best way I have seen so far, and might ultimately, be the best way going forward. To prove this point I will discuss in a future post, the success I've had with pest control in the past few years (for the most part (Not withstanding the times where I think my greens are dead but they actually aren't...thanks T)). Never needed less There are
Read more

Do you have enough?

I recently discussed how we can use fertilizer ratios to simplify how much fertilizer we apply to help us keep above the MLSN guidelines . When we get a soil test done it is a static amount of nutrients found in the soil. Even if you are above the MLSN guidelines at the time of testing, it doesn't guarantee that you will remain at or above the guidelines as the grass grows and consumes nutrients. There is math that you can use to determine exactly how much nutrient you need to apply to ensure that you remain at or above the MLSN guidelines. For many, this is much too complicated. For that reason I made a quick cheat sheet to help you determine how much of each nutrient you can expect to use each year based off a few different annual nitrogen rates. Nutrient use is based primarily on nitrogen use so the left 2 columns are a few different nitrogen rates. The columns for each nutrient are in PPM and are designed to help you look at your current soil test PPM (mehlich 3) and determin
Read more

How to quantify nutrient content in liquid fertilizer

In a recent post, I discussed how it was actually cheaper to spray soluble vs granular fertilizer. What about if we use pre-mixed liquid fertilizer? How do we even figure out how much nutrient we are applying with pre-mixed liquid fertilizer?  Before I learned that you could simply dissolve soluble fertilizer in water and apply it in a sprayer, I was a big user of pre-mixed liquid fertilizers. One of the issues I initially had was figuring out exactly how much of each nutrient I was applying. The math wasn't as straightforward is it was with granular fertilizers. It turns out, it's actually not that difficult but requires an extra step.  First, we need to convert the liquid volume into a mass. Many products will have the product density displayed on the label or you can look in the Safety Data Sheet (SDS) for that information as well. No SDS? Should you be using products without an SDS? Even if this information isn't included on the label it is very easy to figure out. All
Read more