Grubs

Beetle grubs (larvae) eat grass roots. If your lawn has yellow patches, try pulling the grass up in those areas. If it lifts up like a carpet, grubs may have severed the roots of the grass. If you see birds pecking away on your lawn, a skunk digging, or groundhogs burrowing, check for white grubs before chasing the animals away. To controI grubs, spread a mixture of diatomaceous earth and soap powder at a rate of 6 to 9 kg per 100 m², or a tablespoonful of pyrethrum dissolved in 4 L of water, up to four times a year. A high-potassium fertilizer, such as seaweed, may be applied in fall to help the lawn resist the cold. In addition, beetles like to lay their eggs in compacted soil, so aerating is important.

If you see chinch bugs in the spring, you can apply rotenone, diatomaceous earth or pyrethrum. Another way to get rid of these pests is to spray with soapy water once a day for 10 to 14 days, or with a handful of wood ash and lime dissolved in 8 L of water. Spread a flannel sheet over the treated area, and wait 15 to 20 minutes: the bugs will be clinging to the sheet and you will be able to drown them in a bucket of soapy water or suck with a vacuum cleaner. Good lawn care is also important for reducing the insect population to an acceptable level. Fertilizing the lawn in the spring and fall, and proper watering - in the morning rather than the evening - favours the growth of grass and discourages insects. In addition, dethatching in September robs insects of potential habitats.

Earthworms aerate the soil and so should not be destroyed. In September, earthworms come to surface briefly to breed. If you see their castings in the summer, it is probably a sign that the grass is too short or that there is organic matter on the lawn that has not decomposed properly. The recommended cutting height for lawns is 7 cm. As a last resort, you can use sulphur or diatomaceous earth to reduce the earthworm population.

The presence of weeds is often a sign of fertilization or lawn care problems. Before applying a treatment, find out whether this is necessary. Cutting the grass too short favours the development of weeds.

Cinquefoil, Dandelion, Sheep Sorrel, Wild Strawberry

Fern, Mint, Plantain, Squirrel Grass, Yellow Nutsedge, Speedwell

Clover, Milfoil, Hawkweed, Spurge, Crabgrass

Selfheal, Wild Onion or Garlic

Daisy, Bindweed, Knot weed, Wood Sorrel

Wild Vine

Diseases, such as mildew and dollar spot, usually develop when a lawn is neglected. Strong soil acidity, poor drainage, overwatering, overcutting, nitrogen imbalances, shade caused by tree cover, thatch, and insufficient aeration are all factors that favour disease. To remedy these problems, avoid watering in the evening, let the grass dry out between waterings, cut off a few tree branches, and have a soil test done to determine your lawn's fertilizer needs. Always remove grass clippings if your lawn shows any signs of disease. Planting a mixture of grasses reduces the risk of serious infection since each grass variety is vulnerable to different diseases.

Since diagnosing lawn diseases can be difficult, you may need a specialist's help to pinpoint the problem. By monitoring your lawn more carefully during cool, damp weather, you may be able to halt the spread of disease in time. A few of the fungus diseases that affect lawns are described below.

Mushrooms are caused primarily by decaying wood in the soil, and they will soon disappear if picked or raked. Rust affects lawns that are poorly maintained and cut too short, and forms red-orange powdery pustules on the undersides of grass blades.

Mildew shows as grey powdery growth on shady areas of the lawn, and occurs in cool weather. To control mildew, cut off a few tree branches to provide more light and air. Snow mould develops when the snow lingers too long in the spring; it appears as white patches of dead grass. In the spring, remove snow from shady areas if it is not melting quickly. Do not apply nitrogen fertilizer in fall, and cut the grass to a height of 4 cm before winter. Dollar spot forms gold-coloured circular patches the size of a quarter on lawns; they appear during wet weather in the spring and fall. The fungus attacks heavily thatched, moist lawns. You should correct the nutrient levels, dethatch, and water in the morning, letting the grass dry out during the dry.

Fairy rings may develop in lawns that are five years old or older. The fungi create circular patches of dead grass with an outer ring of dark green grass. Fairy rings are difficult to eradicate. To control the disease, spike the rings to a depth of 15 cm with a spading fork. Clean the fork carefully with rubbing alcohol after each use. To avoid contaminating the rest of the lawn, you must begin spiking outside the green ring and work inward toward the yellow area. Pour soapy water into the holes daily for a week, and then clean water every day for two months. To get rid of the rings completely, remove the soil to a depth of 25 cm and 45 cm on either side of the green ring. This is an exacting task but it is the only way to eradicate the fungi. Be careful not to drop any contaminated soil or grass on the lawn, or the disease may spread elsewhere.

Good lawn care limits insect attacks, disease and even weeds. To keep your lawn healthy, cut the grass to a height of 7 cm, fertilize adequately with nitrogen, dethatch in fall, aerate the soil in spring and fall, water thoroughly but infrequently in summer, improve and renew the soil, and prune your trees. In addition, by spraying the lawn with soapy water at the right time, you can control grubs and other larvae.

Alex, JF and CM Switzer. 1985. Ontario Weeds. Agdex 640. Publication 505. Toronto: Ontario
Ministry of Agriculture and Food. 200 p.

Schultz, Warren. 1989. The chemical-free lawn. Rodale Press. Pennsylvanie, U.S.A. 194 p.

Smith Miranda and Carr Anna. 1988. Garden insect, disease and weed identification guide. Rodale Press. Pennsylvanie, U.S.A. 328 p.

Collaborators : Sylvie Deslauriers, agronomist. Département de santé communautaire de Lanaudière

Fore more informations contact :
Environment Canada
Inquiry Centre
105 McGill Street, 2nd Floor
Montréal QC
H2Y 2E7
(514) 496-6851
1-800-463-4311

Published by Authority of the Minister of the Environment

© Minister of Supply and Services Canada 1991
Cat. No. EN 40-206/5-1991E
ISBN 0-662-18785-7