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Removing Recurring Roots & Animals Digging for Grubs

Can anything be done about recurring roots from a Honeylocust tree; and the problem of animals digging for grubs is spreading in Canada!
by Art Drysdale
by Art Drysdale


Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at

August 26, 2012

Above, a shot of Wilson Total WipeOut beside our young Dipladenia Rio Deep Red; and two of white grubs. Below, three shots of a neighbour’s garden in Toronto which had been invaded by raccoons digging for white grubs one entire fall season; and an example of Black vine root weevil damage on a Rhododendron—this can be prevented through use of soil nematodes. Author photos.

This past week Marjorie Casselton from the Simcoe area of Ontario wrote about a problem which is now very difficult to solve if one is going to abide by Ontario’s cosmetic pesticide bylaw—but then who says you have to abide by that ridiculous legislation! Here is her letter.

“I always hear you speaking on our local radio station, CD 98.9 Simcoe, Ontario. The reason that I need your assistance is that we used to have a Honey Locust tree in our back yard. It was doing very well. Not realizing what damages the root system can do. The roots were cracking our paved driveway which we installed about 2 years ago and also we were concerned about our septic system. My husband cut the tree down and had someone come in and remove the stump. With the stump removal they tried to remove roots also.

“Our dilemma now is that we have brought in top soil and trying to reseed the area but we are having shoots/suckers growing up where the tree once was. We need to know on how to stop these shoots from growing or will they stop from continual cutting down when the grass is being mowed. I am hoping you will have some suggestion on how to get rid of these growths.

“Could you please help me out with this problem? I would appreciate any suggestions.”

Marjorie, if it was a different province you lived in, you would have more options; i.e. Roundup or Total WipeOut painted on each of the shoots from the roots of the tree will eventually slow down their production. Now, as you mention, with regular cutting of the lawn, that too will control the shoots, but not, I believe, to the same extent.

Some folks have been known to excavate their lawns to remove a good percentage of the tree roots, and then replace the soil and re-seed or re-sod. This requires considerable effort, so you are likely better to depend upon a product such as Roundup or Total WipeOut. Since you are in Ontario, you may want to pick up a container of such a product while visiting in the U.S.A. It is generally available there. You will likely have a choice of RTU (ready-to-use as shown in the photo here), hose-end applicator, and a container of the concentrate. I suggest you get the concentrate, and paint that (undiluted) to the tree shoot foliage using a paint brush, with the product placed in a plastic container for ease of application.

Be certain to keep in mind that these products will kill anything they touch. If you should happen to spill on the grass in even a small way, just take a watering can or equivalent and drown the area in water. That will wash the chemical off the foliage, and once in the soil it will have no effect on the grass (or the tree shoots).

The pesticide legislation in Ontario is, of course, provincial, and you should have no problem bringing the product across the border. Literally thousands of gardeners are doing this currently and the federally-employed border people generally have no concern about provincial legislation. The products are all tested and approved by Health Canada for the purposes stated on the labels.

A second question arrived from friend Pauline Ashton, who lives in Nanaimo, and who has just moved to a different home there. Here was her question.

“The grassed area to the left of our driveway, between our house and the neighbour's property has, for the last couple of weeks or so, been dug up at night by raccoons. The neighbour's grassed area is also affected. This morning is the worst we have ever seen it with numerous areas dug up. The grass all around our house is in poor shape as it doesn't seem to have had much tender loving care over the years. I am not sure what can be done to destroy the grubs and would appreciate your sage advice.

“We have been thinking of taking out the area of grass and replacing it with river rock. We would of course put landscape fabric underneath the rock. Second question. If we do that are the raccoons going to attempt to get to any possibly remaining grubs?

“I know that in Toronto [and various other centres in eastern Canada] this is a common problem and I gather that it is a growing concern in this part of the world.”

I have already told Pauline the following information, but I thought the questions particularly timely for late August.

In fact there are only two times in a year when it is reasonably easy to kill white grubs that eat away at the roots of grass—sometime in April in most areas when the older grubs are near the surface and easily killed with a chemical; and again usually in the first two or three weeks of August when the new young grubs have just emerged from their pupae and are near the surface voraciously eating the grass roots. The actual very best time to achieve a good ‘kill’ is in August as the young grubs are generally easier to kill than the older ones in the spring. Also, generally the worst damage to turf as a result of racoons tearing up turf to get at the grubs occurs starting in mid- to late-July and can go on well into October and sometimes even November.

Neighbours of mine in Toronto one year each night sat looking as two or three raccoons came and furrowed through the turf in a large area of their back lawn. Generally each night they would start in an area that they had dug up on a previous night, and then expand to an untouched area. By late November, an area at least 20 square metres or over 200 square feet looked as if a farmer had been in with his tractor-mounted disk harrow!

Now, just what to do.

Here in British Columbia, ever since the removal by the Federal Government of liquid Diazinon (12.5%) from the market, the only reasonably good control available to the homeowner/gardener has been use of the chemical Carbaryl (Sevin) 22.5% such as is found in the Wilson GrubOut product. However, if you are a resident of Québec, Ontario, New Brunswick, PEI, Nova Scotia, or Newfoundland (and soon to be added to the list is Manitoba), your stubborn, non-knowing and non-scientific provincial government has ordered products such as these removed from the market, even though they have been declared, ever so many times, by the scientists at Health Canada as perfectly safe for use. Probably no other category of products has been tested as much as these great gardening products.

If you want an example of another category that has likely not been subjected to repeated testing but is still readily available think car antifreeze and even window washer antifreezes! Deadly!

So, as I explained in the earlier question here in the case of Roundup and Total WipeOut, the only answer is to pick up a supply of what you need while visiting the United States.

In answer to Pauline’s second question, about removing the grass totally and replacing it with river rock on top of landscape fabric—this could be chancy if the grub population is not reduced substantially prior to putting the fabric and rock in place.

Just in conclusion, because I know the naysayers will argue that there are a good number of non-chemical safe [not necessarily true] products available for these tasks so that there is no need to use Roundup, Total WipeOut or GrubOut, I should add a comment on Nematodes, which are promoted as an good alternative for the removal of white grubs from your grass. Nematodes [good ones—there are many which are totally negative to many, many plants] are tiny microscopic insects that you water onto your lawn—to control the white grubs which are what the raccoons are seeking when they come along at night and tear up your lawn! Before you go out and spend considerable money on nematodes hear this!

As mentioned here, the single best time for the control of white grubs is at the end of August when the new young grubs become active near the soil surface. At that time too, the soil is warm, and nematodes will have a better chance of working. However, let me advise you that, after having extensive experience with nematodes for well over a decade, they do NOT work well on turf. The problem is getting them through the thatch. Good, honest vendors of nematodes will always advise aerating the lawn well first, and then the nematodes may have a chance to get to feed on the grubs.

Even with extensive aerating of the lawn first, I do not recommend them for that use; but for control of black vine root weevil on such plants as yews, rhododendrons and other shrubs, or for iris borer, they can be used quite successfully since there is no thatch the nematodes need to penetrate.

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