Turf on trial

Field testing is an important part of determining the best rates and uses for new products. This is especially true for biological products, which can be tough to nail down without some evidence from the field. Jim Kerns, assistant professor and extension specialist of turfgrass pathology at NC State, talks to Golf Course Industry about his field tests with Worm Power Turf last year.

How does Worm Power Turf work?
Basically, it has a full suite of microorganisms in it, and the idea is that it has fungi, bacteria and other things that would be helpful, maybe with organic matter reduction and potentially some other turf quality benefits. With a lot of these products, it's really hard to say exactly how they work, and that's where the field testing comes in to show what the results are for that application.

What can you tell me about your field testing?
We did a pretty big amount of testing last year, where we looked at how it influences disease development in dollar spot trials. We looked at it as far as plant health on bentgrass and putting greens. It didn't seem to have much activity on dollar spot, other than the fact that we were able to use what we would consider pretty low rates of fungicide, and saw really good control of the disease. Then, we saw what's called an NDVI (Normalized Difference Vegetation Index) measurement that was significantly better than things we'd seen in the past. It's still pretty new to us, and the best way I can describe it is that we had some promising results that we don't normally see with a lot of biological-type products like this.

We tested this on creeping bentgrass and ultradwarf bermudagrass, from June until August of last summer. We looked at several different rates, including a really high rate, initially, of 32 ounces, transitioned down to 8 ounces every other week. We looked at 16 ounces monthly, as well. We got the best results with the 8-ounce rate every two weeks in our trials, almost a spoonfeeding program.

How might it have helped the turf deal with dollar spot?
We were just able to control it with lower rates of fungicide, and had slightly improved control there. We don't know why that is, maybe a plant health response. That's a problem with a lot of these products. We always want a black and white response, but we might never have one, other than that it works. The reason why, is there's almost 3.9 million bacteria in a gram of this product. It's really, really hard to quantify. The theories behind how it operates make sense to me, but actually trying to test that is a challenge, and that's what we're trying to do this year. We're trying to develop protocols to test it better in the field. A lot of the plant health benefits people are seeing so far, we're going to try to work with Aqua-Aid in the future to quantify more carefully. We've only worked with this for a year, and things like this take time.

How does the NDVI measurement work?
This is a measurement of near-red and infrared light that reflects back from the turf. As you know, green light is absorbed, which is why the plant is green. But there's all kinds of other wavelengths of light that bombard the plant. You want a lot of near-red and infrared light reflected back, because those can be very stressful. Those can degrade the chlorophyll molecule and degrade protein in the plant. The higher NDVI numbers we get back, the more conducive it is for stress tolerance. It didn't seem that it made sense to me, but something was going on that was allowing this plant to mitigate some of that light stress. Why, I have no idea.
We can't really quantify it, because it's a relative number. I can tell you it was the highest rating in that particular trial, the best rating we got. It was dramatically higher than the control, and even higher than a couple fungicides we had in the trial. It was a very unique, unexpected result that I don't know how to explain. We replicated it four times in the field over the course of the summer. It was very consistent.

What about turf quality and health?
For turf quality, most of the plots looked pretty good. They were all better than the control, where we did nothing. When we took the approach to testing it, we tested it against some really strong products. For example, one of the standards was Signature Daconil to Worm Power Turf, and the quality was comparable. To me, that's pretty good.

What tests are you working on next?
We're going to look at it for Pythium root rot, because some of the initial work with the product looked at this with ornamentals and containerized systems. We're trying to work out the details on people using the product in the field. If we can organize 5-10 superintendents to send in plugs, we can analyze rooting and organic matter compared to treated and untreated samples. I think that will give us a better handle seeing its effect with rooting and organic materials.

How should superintendents test this product?
Test it on two or three greens, or strips of putting greens. From the massive amount of photos I see, at the 16-ounce rate it seems to help out with an organic matter problem, with the big glug of microbes there. If they do the 8-ounce rate, that could be something to help them maximize the health of the plant. I think what is happening, because you're putting down a suite of microbes, if you get slow breakdown of that organic material, you're also getting some additional nutrients that you might not have thought about. So it gives them a very stable, balanced nutrient health kind of approach.

About the author
Kyle Brown is a Canton, Ohio-based turf writer.