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THE BULLETIN - May 2007
Spring - every gardener’s favourite season is once again upon us. Although there are still threats of frost and cold nights, the sun is shining and snow and sleet are behind us for now. Nurseries are once more displaying miles of colourful flats of annuals and luscious perennials. Since the majority of us cannot garden à la New York Times, let us hit the plant stores, sales and exchanges and let us get going.
However, since spring also means repairs of winter harms, most of us have to fix fences, cut dead branches and amend the soil. The biggest repair job this year seems to be our devastated lawns which were invaded by grubs last summer and subsequently plowed over by skunks and raccoons . Which brings me to talk about grubs.Grubs
Grubs are the larvae of a brown beetle called June or May beetle. Some sources say grubs have a three-year cycle, others say one year. Whatever their life cycle, they damage the lawn at the larva stage before maturing into pupas and beetles. Although the beetle will not damage your lawn, my advice is if you see one get rid of it, as each female will produce from 25 to 50 eggs which are then laid in the lawn. Those babies will hatch mid-July and start munching right away until the temperature drops and the soil freezes. They will then go down 6 to 12 inches into the ground escaping the autumn frost. The good news is about half of those grubs will get frozen before they dig down and many are eaten by skunks, raccoons and crows. The bad news is that last year the deep frost did not settle until January, a most unusual phenomenon for this part of the world. So, the grubs stayed up and munched on the grass roots for much longer than usual. More bad news, this year we had a few days of intense heat in early April, which invited the grubs to come up and dine on the tender new roots. I predict many grubs will be hungry this summer. What is to be done to firstly prevent these infestations and secondly to repair the damage?For prevention, experts say that a healthy lawn will be more resistant. If you have been feeding it and aerating it properly, chances are you do not have grubs or have a small population that will be taken care of by the birds. We hope. Another way to keep a lawn uninviting to them is to avoid an all Kentucky grass lawn, so choose a mix with a 5% proportion clover seeds to your grass seeds, thereby creating a greener and stronger lawn. Since the beetle likes to lay eggs in short grass, it stands to reason to keep it longer. So either be lazy this summer and leave the lawnmower in the shed as much as possible or set it to cut the grass at a height of 3 inches. Top-dress your lawn with compost now and water it deeply once a week only, because grubs like humid short grass.
If you have grubs you will now see large dry and yellow patches. You can either choose to transform those patches into new flower beds, vegetable patches or try the ground covers that have become so fashionable, or repair the patch and reseed. If you opt for a new flower bed or vegetable garden, cover with new soil, spread some compost and use your imagination or copy the pretty page in the garden magazine. If you wish to repair the dry patch, you will have to scrape the surface dried grass, and cover with a mix of good topsoil and peat moss. An extra load of compost would not hurt. If the patch is large, you may have to resod; if it is a manageable size, grass seeds and constant watering of the spot until germination will do, making sure you keep it bird and cat proof until the grass has grown long and strong.How to get rid of grubs living in the yet undamaged area of your lawn? That is a good question. There is no foolproof way at the moment, although many lawn experts will try and sell you guaranteed and safe-to-the-environment applications of grub control. Experts will tell you this new nematode thing will work wonders. Nematodes are biological control organisms which infect grubs and eventually destroy them. To be effective this treatment must meet many conditions: the soil must be wet and kept wet for several days before the application, the soil temperature must be very warm, around 20˚ or more, which is only reached in July/August, it must not be applied in direct sun, etc. Some studies have been made in and around Montreal. The tests done in Pointe-Claire and Pierrefonds in 2005 and 2006, assuming they were done under the above conditions, concluded to a 35% rate of grub destruction in the treated sections and 10% in the untreated sections. A bit of a hit and miss, I think. The results from the Westmount tests concluded to a 90% destruction of the larvae. We can draw our own conclusions here – either grubs don’t like Westmount much or nematodes got very busy in Westmount. Why?
Another way of getting rid of grubs is Neem oil which is now available at certain nurseries . It is apparently used in cosmetic preparations in certain countries, such as India and Bangladesh, and as a pesticide in the United States. In Canada it is mostly used to make leaves of certain plants lustrous and attractive. In the United States, applications aimed at grubs have apparently been successful at 50%. For use as a bio-friendly pesticide pure Neem oil should be diluted at the rate of 1 teaspoon per quart.I will conclude this grubs business in sharing with you my own grub remedy. Apart from my patch of grass that was devoured four years ago and was finally turned into a flower bed, only a very small patch (2 feet area) got grub-damaged last summer. Evidence of grub infestation becomes visible when the colour of the grass seems to turn into a bluish hue, somewhat in an irregular circle with dead grass in the middle. When I noticed such a change last July, I decided to do some experimentation of my own. Having read somewhere that grubs do not like oak trees, although that theory got contradicted as many times as I talked to oak tree owners, I picked a 2-pound margarine tubful of fresh oak leaves from the neighbourhood. After cutting them up I steeped them in a large pot of boiling water where they remained for a week, probably an overkill when a day or so would have been sufficient. I then watered the lawn with this “tea”, spread the oak mush on the discoloured grass and repaired the damaged patch. I have not seen grub evidence since. I don’t know if the experts would conclude to a miracle or to grubs having a strong dislike to my oak tea. But since the neighbouring lawns all seem to have grub residents, my experiment may have some merit.
A very special thank you to Doris Edwards for the extensive collection of gardening books donated to our Society. They are a welcome addition and Christine Hiller, back in town and in her old job, is busy sorting and cataloguing.See you all at the Plant Sale, on May 26, the Rose & Bloom on June 16, the Garden Tour on July 8, the Day Trip on August 11, the Harvest Festival on August 25.
Until next time.Jacqueline Bouchard
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