New Product for White Grub Control

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White grubs proliferate in some lawns. Photo: http://www.the-scientist.com

If you’ve been dealing with white grubs in your lawn—and losing the battle more often than not!—there is a new biological control product you might want to consider: BTG (Bacillus thuringiensis galleriae). Yes, it has been sold to a limited degree for about 3 years now (and indeed, I’ve mentioned it in this blog in the past), but this year is seeing it on garden center shelves throughout North America. (Sorry, I’m not aware of its availability on other continents.)

How Do You Know If You Have White Grubs?

Usually, it’s pretty obvious! 

They’re essentially a lawn pest. They may be present in other types of garden, but rarely do any visible damage. But they cause lawns to turn brown and even die. 

Holes dug in a lawn by a skunk looking for white grubs. Photo: http://www.whygoodnature.com

Often, the first sign is when you notice holes dug in the lawn by mammals like skunks and raccoons, searching for the delicious grubs. Or hordes of birds like starlings and crows pecking at your turf.

Patches of turf lift right off and sometimes you even see the grubs. Photo: lawnsavers.com

Also, the lawn begins to turn yellow, then brown and will feel soft and spongy to walk on. If you take hold of a section of turf and try to lift it, it will come right off in your hands, its roots having been nibbled off by grubs. 

When you pull the turf up, you may see them just underneath. If not, dig a bit deeper into the soil under the lawn and you’ll find them, smiling lazily at you.

What Are White Grubs?

The various phases of one the white grub beetles: the Japanese beetle. Photo: ohioline.osu.edu

White grubs are the larval stage of various scarab beetles, like June beetles, chafers and Japanese beetles. They’re plump C-shaped whitish creatures with tan or brown heads and 3 pairs of shot legs. They can be tiny at hatching time, but grow over time, some reaching up to 1 inch (2.5 cm) in length. They live under the lawn until late spring of the following year (3 years in the case of June beetle larvae) before going into a short pupal stage, then maturing into adult beetles. 

The adults then dig their way out of the soil and feed on the foliage and flowers of nearby plants, often causing considerable damage (Japanese beetles and rose chafers, notably, are renowned for their destructiveness). Then, after a month or so, females return to lawns, especially low-mown ones, and lay the eggs of the next generation. They soon hatch … and the cycle begins anew.

What Is BTG?

This is the product I’m seeing in local garden centers. Photo: Scotts

Depending on where you live, you many find BTG (Bacillus thuringiensis galleriae) under various brand names. I’ve been seeing Grub B Gon Max locally, but you might find it under the names grubGONE!®, beetleGONE!®, BeetleJUS! or grubHALT!®, among others. (Don’t all those exclamation marks just drive you up the wall!!!)

Bacillus thuringiensis galleriae as seen under an electron microscope. Photo: http://www.sciencesource.com

BTG is a natural bacterium found in soils worldwide. It is specific to beetles in certain families: the Scarabaeidae, Buprestidae, Tenebrionidae and Curculionidae families, thus scarab beetles, wood-boring beetles (including emerald ash borers), darkling beetles and weevils. It will not harm other insects, such as pollinators (bees, butterflies, hoverflies) and predatory insects (wasps, lacewings, pirate bugs, etc.), nor even other beetles, like ladybugs. Nor is it harmful to humans, pets, mammals, birds, amphibians, fish or aquatic insects. 

Some of the Lawn Pests Controlled by BTG

Asiatic garden beetle
Japanese Beetle 
June Beetle (May beetle)
Oriental Beetle
Cupreous chafer
European chafer
Northern masked chafer
Southern masked chafer
Black turfgrass ataenius
Annual bluegrass weevil 

Obviously, BTG is not harmful to lawn grasses of any species, nor indeed plants of any type.

The variety used is a selected strain called BTG SDS-502, easier to produce commercially and more effective against lawn pests than other strains.

When the larva consumes the bacterium, it produces crystal proteins that poison its host, causing it to stop feeding. The grub gradually becomes paralyzed, then dies. The results are often noticeable within a week or so, as turf often recuperates quite quickly once its roots are no longer being eaten. 

Apply BTG with a spreader. Photo: murraylawnmowerparts.com

The product is usually applied to lawns with a spreader (the same type used for applying fertilizer and lawn seed), then watered in so the bacteria descend into the soil layer where the larvae live. Powdered forms can also be sprayed onto the foliage of susceptible plants to control adult insects, but they do not appear to be widely available at this time. 

Recommended application times according to grubGONE!®. Ill.: grubGONE!®

BTG can be applied to lawns at any time from spring through late fall. Usually, though, the best results are obtained by applications in July or August, timed to reach young larvae just emerging from eggs laid by adult females (they hatch in 10 to 30 days, depending on the species). However, many gardeners apply it in spring to control the damage animals cause as they search for larvae, in which case a second treatment will likely be needed in summer or fall to reach the grubs of the next generation.

Not to Be Confused With…

Beneficial nematodes. Photo: CSIRO

BTG is not the same thing as another grub treatment, beneficial nematodes. In fact, the two actually complement each other, each attacking grubs in different ways. Nor is it the same thing as milky spore disease (Paenibacillus popilliae), used specifically to control Japanese beetle larvae.

Is BTG Effective?

You tell me! I’m generally hearing very positive feedback about this product, but it’s fairly new. Time will probably tell. And I won’t be able to test it myself, as I’ve never had a white grub problem. 

Certainly, it would be worth trying if white grubs are ruining your lawn, especially if you’ve been using poisonous chemicals to control them or hiring lawn care companies to do the dirty work for you. And if enough neighbors use it, it might also bring down the damages from adult beetles, like Japanese beetles, to a more acceptable level.

Try it and see!

Using Beneficial Nematodes Against White Grubs

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White grubs at three different stages. Photo: David Cappaert, Michigan State University, Wikimedia Commons

You can treat infestations of white grubs (larvae of June beetles, European chafers, Japanese beetles, rose chafers, etc.) in the lawn with nematodes, small parasitic worms that infect and kill young larvae. There are various species of nematodes that will do the job, mostly in the genera Steinernema and Heterorhabditis. They work by penetrating their host and injecting bacteria that kill them.

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Nematodes are parasitic worms too small to be seen by the naked eye. Photo: CSIRO

Note that beneficial nematodes are harmless to beneficial insects, such as bees and ladybugs, as well as earthworms, and also to birds, reptiles, amphibians, mammals, etc., although they also help control other harmful soil insects such as weevils, fleas, borers, wireworms, onion maggots and fungus gnats.

In the Northern Hemisphere, nematodes are best applied at sunset or on a cloudy day between mid-August and early October in cooler climates, mid-July through August in mild ones, as that is when the grubs are freshly hatched and most vulnerable to infestation. The soil should be warm (70 to 86˚F/21 to 30˚C) and moist (apply after rain if possible, otherwise water deeply the day before).

 

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Some brands of nematodes can be stored at room temperatures.

You should be able to find beneficial nematodes in your local garden center. If not there are many mail order sources on the Internet. In years past, you had to ask for them, as they were stored out of sight in a refrigerator (likewise, they have to be stored in a refrigerator at home until you’re ready to use them). However, recent technological developments in storage methods have led to some brands that don’t require refrigeration, although they must not be stored in sunlight.

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Nematodes can be applied using a hose-end sprayer. Photo: Spray-N-Grow

To apply, mix the product in water and spray on the lawn, following the instructions on the product purchased (they’ll vary a bit depending on the species of nematode and the way the supplier has packaged them). Water the lawn after the application and as needed over the next 14 days so the soil remains moist, especially in heavy or clay soils, as this ensures that the nematodes will descend deep enough into the soil to reach their prey.

Combined with other control methods (such as turf enriched with compost, mowed high, and mixed with other plants such as clover), you’ll find nematodes quite effective… in the medium and long term. But not necessarily the following year! That’s because nematodes are especially efficient in killing freshly hatched white grubs in the first year of their cycle, the ones that hatch in July (mild climates) or August (cool climates). They’re not so good at controlling 2nd-year grubs (those that live two years underground, as is the case with June beetles), the ones that will cause the most damage the following year. That’s why it is often in the third summer you’ll see the full results of your treatment, because that year’s generation will have been largely eliminated. Once introduced, beneficial nematodes can remain in the soil for many years, providing long-term control.

Note that it is not necessary to eliminate all the white grubs from a lawn to get excellent results. A healthy lawn can tolerate a modest population of white grubs without showing the typical symptoms (brown patches in the lawn). That’s what you should strive for: a natural balance in your lawn’s environment, one that will give you a healthy lawn without disrupting Mother Nature’s cycle.20170828C CSIRO

No-Hassle White Grub Control

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(The Less You Do, the Fewer You Will Have)

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In most areas, damage to lawns from white grubs begins to appear in July. You’ll see patches of yellowed, dying grass appear here and there. When you pull on these patches, they lift right up with no effort and you can see grubs (plump whitish C-shaped larvae) in the soil underneath. Also, different animals, including skunks, dig holes in the lawn in search of grubs, thus signaling their presence.

To try to control white grubs, learn not to mow too short (never below 3 inches), because adults (June bugs, European chafers and Japanese beetles, all large beetles) prefer to lay their eggs in short grass. In addition, mowing the grass short stresses the lawn itself, so when when grubs are present, it suffers to a greater degree (long grass lawns can sustain considerable grub populations with no obvious symptoms). Always leave grass clippings on the lawn, as they repel adults. Also prefer a lawn containing a good portion of plants other than grass – clover, thyme, ground ivy, etc. – as adults prefer lawns largely composed of turf grasses. Learn to tolerate the presence of small ant nests in the grass, as ants greedily consume beetle eggs. Finally, avoid watering the lawn during drought, as grubs die massively when the lawn goes summer dormant.

And there you go: lots of tips on dealing with grubs, simply by doing less work rather than more!