Expert opinions on ABW, white grubs

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Steve McDonald and Ben McGraw share their perspective on what you might be able to expect from pests in 2020.

April 2, 2020

An example of damage caused by white grubs.
© Rob Golembiewski

Temperatures are starting to jump across the country and all sorts of pests are warming up for their perpetual return. Prepare yourself.

Bayer is still awaiting EPA approval for its new insecticide with the active ingredient Tetraniliprole — the company expects the green light later this year — but a number of industry experts have been testing it for years. We talked with two of them — Steve McDonald and Dr. Ben McGraw — for their perspectives on the latest addition to the diamide insecticide field and, more generally, about what they have found in their recent annual bluegrass weevil and white grubs research.

Steve McDonald

McDonald is no stranger to golf courses, visiting more than 200 annually as the owner and operator of Turfgrass Disease Solutions. His current research focus is the practical management of problematic disease, insects and weeds in highly maintained turfgrass. He teaches in the professional golf turf management program at Rutgers University.

McGraw is an associate professor of turfgrass science at Penn State University, where his areas of expertise include turfgrass entomology, biological control, cultural and mechanical control, and, key for this discussion, insect behavior, insect ecology and insecticide resistance.

Ben McGraw

What recent developments in ABW and white grub research are key for golf course superintendents to at least know about, if not also implement?

Steve McDonald: The big one that Ben and I would probably agree on is resistance within the bluegrass weevils and various classes. New tools like Tetraniliprole are critical, and also making sure that you’re rotating in other diamides properly in resistance management is key. The products are so effective that the tendency is to overuse products like Tetraniliprole, but superintendents should be encouraged to make sure they’re timing their insecticides properly and considering rotation where and when possible. For white grubs, one of the keys we’re seeing is more consistent control in thatchier turf where the older chemistries hadn’t been working as well.

Ben McGraw: The loss of some products is potentially coming down the pipeline. Our lab is heavily invested in annual bluegrass weevils, so our focus is mostly there. Other colleagues across the country might focus a little more on white grubs, and so I would defer to them on new developments with grubs. I would say most of the changes in turf insect management are changes in chemical management. And environmental challenges have made it difficult for pest control the last couple of years — extreme weather affecting control or allowing insect populations to get really large. Those are the latest developments.

Among superintendents and other turfheads you talk with, what are the most common complaints about ABW and white grubs?

McDonald: The biggest issue about controlling annual bluegrass weevils is, particularly in the Mid-Atlantic region, they can damage turf from May through November, so it’s a very long season. The biggest complaints are the costs and that potential for pest damage over such a long window. Materials like Tetraniliprole that provide 21 days of control in trials, and sometimes more — and timing those products properly — are the critical things.

McGraw: The complaints from the last couple of years for ABW, I would say what is different, is we do seem to have a lot more damage that occurs in the summertime. Traditionally, it’s really worse in the spring generation — in our area, that’s May or early June — and usually if you can get things under control during that generation, then it’s rare that we have widespread damage in the summer months. What we’ve had a lot of reports of is more damage occurring in the summertime and that can be due to additional stresses, but also populations seem to be hanging around later in the year.

What new processes or tools for controlling them have performed best?

McGraw: Tetraniliprole is part of the anthranilic diamide family. Fortunately or unfortunately, depending on how you want to look at it, all of the major products in that family work against larvae. They’re all newer-generation insecticides, they’re all softer chemistries, they’re all very effective and they all have subtle nuances in the timing or the application of the product.

McDonald: With a lot of these newer chemistries like Tetraniliprole, they appear to be very systemic in the plant, meaning they penetrate plant tissue rapidly and they move to points where insects are feeding. Golf course superintendents would historically try to limit water to the golf course only when they need to and a lot of these new chemistries have the ability to move rapidly. Products like Tetraniliprole, when we tested this, did very well when watered in 24 hours after application and the turf is not mown. My general rule of thumb on new processes and tools would be to definitely water it in lightly — one-tenth of an inch — before you mow it.

You’re spending a significant amount of money on these plant protection materials and you really want to optimize your delivery. These weevil and grub insecticides, you really want to consider the placement so it’s covering all the pests you’re trying to control.

Bayer has been testing its Tetraniliprole for more than half a decade and started promoting it at the Golf Industry Show in January. How might that new active ingredient affect ABW and white grub control?

McGraw: It’s an anthranilic diamide that appears to have very good residual activity, so it can be applied preventively and last for some time in the environment where it controls the insects without fear of missing a population or things emerging too early or too late, so it gives a little more flexibility as to when it can be applied relative to the insect stage. Along those lines, what appears to be different in our testing is that it does seem to have some curative activity, which is unusual for an anthranilic diamide, so it does appear to have quite a bit of flexibility in timing — not just preventive timing but also in the curative control.

I still want to see this product in testing, especially because the curative activity is rather unique and I’d like to see if that’s a real phenomenon. That was one of the most interesting trials we did last year. Still trying to figure out the timing of it, because that would be a big one if it could be used in a rescue treatment.

McDonald: It definitely has a fit as far as new options for programs to include Tetraniliprole into a programmatic approach for annual bluegrass weevil and white grub control. Any time you can have a new active ingredient that fits into a program — especially when they consider what I call the whole insect-pest complex, not just annual bluegrass weevils — (it can provide another option).

What other perspective — general or specific — about this corner of the research sector would you absolutely want to share with turfheads? What do they need to know?

McDonald: Now that there are three diamides in the turf market, making sure they are properly rotating through the diamide class, that they consider it an alternative insecticide, that would be the absolutely critical thing with Tetraniliprole, just that they’re rotating. We’ve tested Tetraniliprole for going on three years, we’ve done various insect pest control tests and we’re going to look at it again in 2020, which is great.

McGraw: I think rotation is good. It’s important to know that this is a tool and we want all of our tools to work effectively for as long as they can. Even when a new product comes out with some interesting activity or provides a high level of control against our target pests, we still want to be conscious of rotating these products, rotating active ingredients. ?

Matt LaWell is Golf Course Industry’s managing editor.