“If you kill off the natural enemies of garden pests you inherit their work.”
On a recent trip to Halifax a man sitting two seats behind me on the plane asked if I knew what insect was causing the perfectly round holes in his lawn that seemed to appear overnight. As I generally do under these circumstances I asked a few questions before jumping to conclusions (though, a knowledgeable gardener reading this may already have this one figured out).
The holes were the size of a nickel across and a couple of centimetres deep. They were randomly spaced and every few holes had been expanded and ‘ripped apart’ as if someone had put a firecracker in the hole. “It is not an insect. You have a skunk.” I concluded out loud to the horror of the man who asked, perhaps regretting that he had brought it up. The people on the plane around us had a silent chuckle. What is it about a skunk that makes people laugh? Like standing on a rake and hitting yourself in the head, it is always funny when it happens to someone else.
For the most part I find skunks harmless creatures. Their biggest problem is that of public relations: they stink. The holes in the lawn are the result of a hungry and curious skunk that is literally sticking its nose in your business (i.e. lawn) looking for grey and white grubs. Once it smells one with its finely tuned, perfectly round little nose it digs up the grass and soil until it exposes it for a little ‘shrimp cocktail’. Much worse, in terms of damage to your lawn, is that caused by a racoon for the same purpose.
Skunks and racoons
Both racoons and skunks eke out a living by foraging for grubs. And this is prime grub season. The larvae of the June beetle (grey grub) and the European Chafer (white grub) are interesting in that they are both migratory and constantly changing. Unlike birds, which fly south in the winter, the grub migrates through the soil during the gardening season, moving close to the surface this time of year as they seek out the young white roots of your lawn in their desire to find a meal.
If the skunks and rodents are coming to dine at your place I have some good news for you. With the grubs up near the surface of the soil this is the perfect time for grub control. In the absence of chemical control for grubs we now use beneficial nematodes. These are microscopic organisms that you water into the lawn. Literally they feed on the backs of the grub and make a meal of them (in this story it seems that everybody is eating everybody). The beneficial nematodes are the ‘good guys’. I remind you that over 90 per cent of the insects in your yard and garden are beneficial and do not do harm to your plants.
Natural born killers
Nematodes are sold at your local garden retailer from a beer fridge. While kept at cool temperatures they remain dormant and awaken when brought out to normal temperatures. A package of nematodes may read, “Contains 10 million natural born killers.” They are sold in a small box in which a smaller plastic envelope containing an even smaller sponge is saturated in the microscopic organisms. These nematodes are harmless to people, plants and pets. They occur naturally in the soil: you are just adding to an existing population in your efforts at grub control. As long as there are grubs to feed on, the nematodes persist in the soil. When your grubs are gone the nematode population declines naturally.
It should be noted that a thorough drenching of your lawn is in order, before and after the application. Apply at least an inch of water as this will force the nematodes deep into the root zone of your lawn where they can seek out and destroy the grubs.
A healthy lawn is your best defence
One other very important caveat: your lawn is of much less interest to grubs and the skunks and racoons that seek them when it is green and healthy.
I recommend that you cut your lawn at least two and a half inches high as the higher the grass blades the deeper the roots and the more drought resistant your lawn. Also you will shade out 80 to 90 per cent of the weeds that would otherwise germinate there by seed.
Use a mulching mower for even better results, returning the nitrogen rich goodness of the clippings to the root zone of your grass plants. You will not build up the thatch layer of your lawn with a mulching mower.
The recipe for a healthy lawn is complete with the application of a quality fertilizer three or four times a year. Make sure that it has slow release nitrogen in it to nourish the lawn for up to 10 weeks. If you fertilized early in the season you could do it again now, unless you fear that we are heading into a drought in which case there is no need. The late summer and fall applications are important.
As for watering, I do not recommend it this time of year unless of course you are applying nematodes. Let your lawn go dormant, should we run into a stretch of hot, dry weather. Your lawn will go brown, to be sure. But if you have followed my advice here it will bounce back come August when evening temperatures drop and evening dew heavies up. Meantime, you will cut your lawn less often, which means more hammock or golf time, or opportunities to work in the garden, pleased with yourself that the grubs, skunks and racoons are under control.
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Mark Cullen is Canada’s best-known gardening broadcaster and writer. He is the spokesperson for Home Hardware Lawn and Garden. Sign up for his free monthly newsletter at www.markcullen.com and watch him Wednesday mornings on Canada AM. His column, which focuses on our growing zone, appears in the Hants Journal every two weeks.