White Grubs Still Pose Challenge to Turfgrass Research

White grubs have been one of the key insect pests of turfgrass throughout the world and in particular in the United States. Very few locations that can grow quality turf are immune to potential damage from the larvae of a number of beetles. The feeding of the grubs damages turfgrass by destroying the integrity of the root system, loosening the soil and often attracting various predators that destroy the turf to gain access to the grubs as food.

There is a wide range of grub species in the country ranging from the Japanese beetle grub to grubs of the Oriental beetle, green June beetle, European chafer and various masked chafers to name a few. Life cycles vary, as do the preferred sites of infestation. Despite the variations and differences, there is one consistent theme: White grubs are as much, if not more, of a problem today, than at any time in the past.

Maybe it is our increased expectations and desire for the perfect golf course or sports field that make it appear to us that grubs are now more serious than in the past. It is possible our increased use of irrigation and other cultural practices have made turfgrass in many areas more susceptible or a better host. Maybe it is simply that the white grubs are taking advantage of what we are offering — better food and a more suitable environment.

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Whatever the reason and whether it is real or perceived, if we add up all the insect concerns across the country, I think we'd find grubs would rank as No. 1. Fire ants, mole crickets and other pests may certainly be more of a problem in selected locations, but overall grubs stay at the top. Grubs remain a serious problem primarily because they are soil insects that live underground. This creates problems for early detection and getting the insecticide in contact with the white grub.

Modern insecticides such as Mach 2 (halofenozide), Merit (imidacloprid) and Arena (clothianidin) work most effectively when applied in a more preventive manner rather than as a rescue to clean up an existing problem. This requires a thorough knowledge of pest history of infestations and the life cycle of the insect. While this was initially a big shift in thinking for most turfgrass managers, we have become fairly proficient in our wise and cost-effective use of these materials.

Even with new, more environmentally sound materials available, it is important that we develop a better understanding of white grub biology and the factors that influence white grub infestations and management. Perhaps that should be restated to say that now with the new insecticides, it is more important than ever to develop the best possible understanding of pest biology. While scientists have been studying white grubs for a long time, there is still a lot to learn.

Add to this the fact that our turfgrass systems have also evolved over the last 25 years and it leaves us with much still to learn about white grub biology and ecology. Some areas, such as the southern United States, lag behind in our database for understanding white grubs. The rapid population increase in the South over the past 25 years has resulted in a lot more turfgrass and new problems showing up throughout this region.

Unfortunately, we don't have a lot of history of research in some areas and we can't always extrapolate information from other areas. As a result, there's a lot of research taking place in many locations focusing on white grub ecology and management.

In North Carolina, we have experienced an increase in white grub problems in turf on both warm- and cool-season turfgrasses. There are problems with southern masked chafers, northern masked chafers, Oriental beetles, green June beetles, Japanese beetles and others depending upon the location and type of turfgrass. The severity of the problems, the cost of control, and the need for effective control has prompted renewed research to gain better insight into white grub biology in the Southeast. It is hoped that this research in conjunction with other studies, such as those by Dr. Eileen Buss at the University of Florida, will paint a clear picture of white grub problems in the Southeast and add to our understanding of these pests on a national basis.

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