How destructive are fungicides?

Kentucky bluegrass, Fescue, Rye and Bent, etc
Post Reply
User avatar
PSU4ME
Posts: 996
Joined: November 29th, 2016, 9:29 am
Location: Central MA
Grass Type: Front: Bewitched/Midnight/Everglade Back: Midnight/Diva/Everest
Lawn Size: 20000-1 acre
Level: Some Experience

How destructive are fungicides?

Post by PSU4ME » July 7th, 2019, 5:27 pm

I am really hesitant to use any fungicides because I’m trying to take the approach of having a good healthy soil. I’m running companion, tko phosphite, KH and serenade this year and I’ve been pretty happy..... also got down a healthy layer of compost this winter/spring on a good portion of the lawn so I know the life is there.

I continue to battle red thread though and it ticks me off. I know the grass will snap back and the above program is helping keep it at a manageable level but I keep on wondering if I should introduce some propiconazole 14.3 apps into my routine.

I’m afraid that it’ll ruin the hard work I have into the soil and with the RT being manageable, I don’t “need” to resort to fungicides.

But I would like to know how bad is an app or two here and there? I’d like to give the RT a few good body blows to see if I can really kick it.

I’d love your thoughts. Thanks!

User avatar
McLovin
Posts: 687
Joined: February 25th, 2009, 12:40 pm
Location: Middle Tennessee
Grass Type: TTTF
Lawn Size: 20000-1 acre
Level: Novice

Re: How destructive are fungicides?

Post by McLovin » July 7th, 2019, 11:01 pm

I use fungicides to control brown patch. Here is a thread of interest.

viewtopic.php?f=4&t=13904

IMHO I think tiemco hit it out of the park.
tiemco wrote:Has anyone ever looked at the literature regarding the results of turf fungicides on soil fungal populations? Well I have, and I think I am the only one. Seems like the idea that fungicides completely destroy the soil microherd is basically doctrine on BL/ATY, unfortunately it's not true. There are plenty of published studies showing that most fungicides have little to no effect on soil populations, and when they do, the rebound is generally very rapid. In some studies you will actually see an increase of soil bacteria. A good majority of fungicides are systemic, which means they are incorporated into the actual plant, with very little soil interaction. Many of the newer fungicides available are much more targeted as well, thus reducing collateral damage. The strobilurins (Heritage, Disarm, et. al) are derived from chemicals released from naturally occuring fungi, sort of like how Tenacity was developed. Most turf fungicides are used in very small amounts, and generally don't penetrate the soil to a great extent. Let's take Disarm G, a fairly new stobilurin fungicide. At 2-4 lbs. per thousand you are actually using .08 - .16 ounces of fungicide per 1000. A good portion of that will enter the plant, and the rest will probably just sit on the top of the soil until it degrades or is consumed by bacteria. Also many fungicides are not terribly water soluble, so soil penetration is generally low. Here are a few studies for anyone who wants to read up on this:

(urls deleted)

Now I am not advocating using fungicides every 2-4 weeks during the growing season, but when the weather and conditions become very favorable for fungal disease, an application or two of fungicide can go a long way in reducing the risk and damage of pathogens, with no to little harm to the soil biology.

User avatar
andy10917
Posts: 29091
Joined: February 23rd, 2009, 10:48 pm
Location: NY (Lower Hudson Valley)
Grass Type: Emblem KBG (Front); Blueberry KBG Monostand (Back)
Lawn Size: 1 acre-2 acre
Level: Advanced

Re: How destructive are fungicides?

Post by andy10917 » July 8th, 2019, 9:14 am

My research and personal experience has led me to avoid the application of synthetic fungicides as regular preventative applications for a few reasons.

The first reason is that many fungicides don't only kill the target disease fungi, but affect the entire biomass (what we like to call the Microherd). This effect in harming both the fungal and bacterial "non-target" parts of the microherd means that the fungicide diminishes the good guys along with the bad guys, and the end result is a soil that is weaker at warding off disease on its own. Over time, this can lead to a dependence upon synthetic fungicides to control fungal disease.

The second reason is that over time, the target fungal pathogens become "resistant" to the fungicides - which is why a rotation program is required. But if you're using them even when there is no visible active disease, you're still encouraging the resistance to develop, and the time will come when the fungicide no longer works - perhaps exactly when a severe breakout of disease happens.

I'm not "anti-synthetic" in the use of fungicides, but I see them as firefighting tools when all hell has broken out, and even then using them only in areas with active infections and the margins nearby. For preventative practices, I strongly believe that the best course of action is to build the microherd with types of bacteria and fungi that naturally prey upon the "bad guy" fungi and keep them in check. It's worked very well for me and others that I have recommended the practice to - I have not had a fungal attack in 8-9 years now.

Look, it takes time to build up the microherd to do that type of work. When your house is on fire, it's not the time to discuss the purity of the water being used to fight the fire - it's time for action and accepting the collateral damage that may occur. I get it. But as many members here have found, building the anti-pathogenic members of the microherd is a proven practice.

The searchable research is pretty difficult to read, but using terms like "non-target", "biomass", "fungicide" will find what's available if you choose to dive deeper...

User avatar
HoosierLawnGnome
Posts: 9587
Joined: May 22nd, 2013, 5:59 pm
Location: Indianapolis, Indiana
Grass Type: Blueberry KBG
Lawn Size: 1 acre-2 acre
Level: Advanced

Re: How destructive are fungicides?

Post by HoosierLawnGnome » July 8th, 2019, 9:37 am

I think lawn care is often deciding between the least of two evils. Perfect is the enemy of good and all that.

So what's better for your goal? A raging disease or reduced microherd?

Besides people often forget the cultural side of treating fungus. Some fungi can be outgrown by encouraging growth, applying Nitrogen and changing watering habits.

User avatar
andy10917
Posts: 29091
Joined: February 23rd, 2009, 10:48 pm
Location: NY (Lower Hudson Valley)
Grass Type: Emblem KBG (Front); Blueberry KBG Monostand (Back)
Lawn Size: 1 acre-2 acre
Level: Advanced

Re: How destructive are fungicides?

Post by andy10917 » July 8th, 2019, 9:46 am

+1. Agreed! What I was trying to get to was that it's a balancing act - use the "nuclear option" only when absolutely necessary, but don't be tentative when you're in a tight spot with a raging infection.


User avatar
bernstem
Posts: 4230
Joined: April 15th, 2011, 2:59 pm
Location: St. Louis, MO
Grass Type: Front: Solar Eclipse/Award/Bewitched/Moonlight SLT/Prosperity Back: Solar Eclipse Monostand + Bewitched (shade)
Lawn Size: Not Specified
Level: Not Specified

Re: How destructive are fungicides?

Post by bernstem » July 8th, 2019, 9:49 am

I have looked at the data on Fungicides on lawns. There is definitely an effect. While total fungal population numbers stay roughly the same or decline slightly, there are dramatic shifts in the members of the population with non targeted fungi taking the place of the the targeted fungi. After stopping them, there is then a shift back to the pre-treatment populations. We would also be naive to think that fungicides are not going to affect a broad range of fungi outside of the disease organism.

Ultimately, whether you use fungicides or not, the overall health of the lawn and turf is critical. If the lawn is not happy, disease will hit it harder and result in more damage. That means that if you have disease issues, you really need to be figuring out what you can do to minimize the impact or prevent it. That may mean chemicals, but the chemicals are only a part of the disease treatment and prevention plan. You also need to look at overall cultural practices such as mowing, fertilizing, soil management, watering, etc.

Lastly, I think that people need to look at where they are growing and what grass they are growing. The farther from the ideal conditions you have for your chosen turf, the harder it will be to deal with issues. KBG in the north is quite disease resistant. KBG in the transition zone is a completely different growing experience.

Ultimately, every individual will need to decide what the best approach is for their lawn. That will be a very individual choice. I would say if you are using a non-chemical approach and seeing good results you should stick with that.

User avatar
HoosierLawnGnome
Posts: 9587
Joined: May 22nd, 2013, 5:59 pm
Location: Indianapolis, Indiana
Grass Type: Blueberry KBG
Lawn Size: 1 acre-2 acre
Level: Advanced

Re: How destructive are fungicides?

Post by HoosierLawnGnome » July 8th, 2019, 10:26 am

Yeah, I want to have a perfect lawn I never mow, apply chemicals to, add fertilizer to, is weed free, and requires no use of water to retain at that level. Every blade is at the same height and evenly spaced. Yet......

User avatar
andy10917
Posts: 29091
Joined: February 23rd, 2009, 10:48 pm
Location: NY (Lower Hudson Valley)
Grass Type: Emblem KBG (Front); Blueberry KBG Monostand (Back)
Lawn Size: 1 acre-2 acre
Level: Advanced

Re: How destructive are fungicides?

Post by andy10917 » July 8th, 2019, 10:34 am

We all know how likely that is to happen (why do I hear strains of the Rolling Stones singing "You can't always get what you want" in the background?)

User avatar
HoosierLawnGnome
Posts: 9587
Joined: May 22nd, 2013, 5:59 pm
Location: Indianapolis, Indiana
Grass Type: Blueberry KBG
Lawn Size: 1 acre-2 acre
Level: Advanced

Re: How destructive are fungicides?

Post by HoosierLawnGnome » July 8th, 2019, 10:46 am

I'm still a newb in many ways with respect to horticulture overall, but I think of things this way:

In what conditions will the plant be healthiest? How can I encourage and maintain it at that level? Whether it's a rose, blade of grass, tree, or hosta - if it is healthy it will be attractive.

Just like the human body, beauty = health, ugly = sick or dying.

I have a good friend in the soil and water conservation consultation industry - gives me a hard time on my "unnatural" or "artificial" turf. He's right. It's not meant to be cut at 1.5". Or at 4" really. It wants to be taller. The plant is bigger and stronger there. But we don't like to look at it like that. There's something we find beautiful about an orderly and healthy group of plants. Left to itself, it can trend towards disorder or sickness.

It's not unlike managing timberland (which I also do some of). You have to manage the timber. Trees die. They fall over and need removed. You can't have too many in a spot and they need to the right location. If you leave woods to grow unmanaged, fire will ravage it eventually and that isn't always good. A healthy stand of trees is one that is groomed and maintained, properly harvested occasionally. Now it's productive. Big trees can grow intead of a bunch of small, sickly ones.

Post Reply

Who is online

Users browsing this forum: ken-n-nancy, Ogden and 2 guests