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Gardening … all naturally
2011 Edition
Opt for alternatives to pesticides
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How to
solve the problem of undesirable organisms and diseases in your flower
beds and garden |
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Undesirable organisms and symptoms |
Tricks and suggestions for prevention |
Alternatives to pesticides |
Pesticides: a last resort1 |
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Slugs and snails - Eat plant leaves.
- Easier to spot at night when they are more active. |
- Create a barrier around your flower beds
and garden using oven-dried crushed egg shells (pluck up the slugs and
snails already on the scene). |
- Place a receptacle (saucer) or a
commercial trap containing beer or a mixture of water and yeast on the
ground, making sure that the edge of the receptacle or trap is at ground
level; empty and replenish as needed.
NB: Slugs are attracted by the yeast in the beer.
- In the evening lay wooden boards on the ground, and in the morning
pluck up the pests hidden underneath.
- Use copper bands available in retail outlets as repellent barriers.
Slugs are made up almost entirely of water and receive little electric
shocks upon contact with copper. |
- Ferric sodium EDTA
- Ferric phosphate -
Diatomaceous earth |
| Cutworms - Cut plant stems.
- Easier to spot at night when they are more active. |
- Plant marigolds (French marigolds) since
these flowers repel cutworms. - In fall, remove all plant debris from
your flower beds and garden.
- Dig and turn over the soil in fall. |
- As the plant begins to grow, place a
bottomless tin can, a plastic cup or a sheet of aluminum foil around the
stem, sticking up at least 5 cm above ground level and pushed in at
least 3 cm beneath (do not remove for 3 weeks). - After sunset, using
a flashlight, carry out a cutworm collection. |
- Rotenon |
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Colorado potato beetles (“potato bugs”) -
Feed on potato leaves.
NB: Not to be confused with ladybugs, which are
useful. |
- Plant garlic or marigolds between rows
since these plants repel potato beetles. |
- Eliminate by hand the masses of orange
eggs found under the leaves (usually in June). - Water leaves with a
powerful spray in order to dislodge the bugs.
- Pluck up larvae, as well as adult insects, in April, May and
September. |
- Rotenon
- Pyrethrins |
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Earwigs - Are fond of damp, dark places.
- Generally easy to catch.
- Easier to spot at night when they are more active. |
- Avoid accumulations of plant and wood
debris. - In spring, on warm dry days, work the soil; this will
disturb the adults and uncover their eggs. |
- Set traps: about 20 per lot, wherever you
spot the pests.
- Use “tunnel” traps of all sorts, around 30 cm in length (garden
hose ends, pieces of bamboo, rolled-up newspapers, etc.) or commercial
traps.
- Shake out the traps in the morning above soapy water. |
- Diatomaceous earth
- Insecticide soap
- Pyrethrins |
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Aphids - Tiny green, brown or black
sucking insects, often found in groups; they cause leaf yellowing and
sometimes deformation.
- May transmit viruses. |
- Foster the proliferation of predators
such as ladybugs and lacewings. - Use the proper amount of fertilizer;
too much nitrogen-based fertilizer promotes the growth of succulent
tissue which attracts aphids. |
- If possible, a powerful spray of water once a day, in order
to dislodge the aphids. |
- Insecticide soap
- Rotenon
- Pyrethrins
- Acetamiprid |
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White grubs (chafer larvae) |
- Turn over soil and if you uncover them
continue digging deeper around the entire area; eliminate all the larvae
you have uncovered by hand. |
- Put bait in soil (potatoes), wait a
couple of days, then turn over the soil and pluck up the pests |
Imidacloprid |
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Lily leaf beetles |
Check lilies regularly during the beginning
of the season. The larvae, which are hidden by their excrements, hide
under leaves. |
Remove larvae and adults by hand. Be
attentive. Adults sometimes drop to the ground to escape gardeners. |
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| Diseases |
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Common Scab - Brown scabs on potatoes,
beets, turnips, etc. To be found in too highly alkaline soil (pH level
above 7). |
- Avoid excessive use of lime and wood ash. |
- Get a pH analysis. - Lower the pH level,
if necessary, using wettable sulphur. |
– No need for treatment. An aesthetic
problem only. |
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Mildew or late blight - “Oily” spots on
plant leaves, followed by a white covering on potatoes and tomatoes. |
- Enrich soil using well decomposed organic
matter. - Choose resistant plant varieties.
- Avoid spraying leaves with cold water. |
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- Copper |
1 Follow the instructions provided on the label of
the product.
To learn about repercussions of active ingredients for human
health and environment, please see the table entitled “Relative
toxicity of the main active ingredients contained in pesticides for domestic
use used for green spaces"
( PDF file,
134 Kb).
| Solutions to the
problem of undesirable organisms affecting your trees and shrubs |
|
Undesirable organisms |
Trees and shrubs affected and symptoms |
Alternatives to pesticides |
Pesticides: a last resort1 |
| Insects |
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Aphids |
- Many species affected (rose trees, plum
trees, honeysuckle, apple trees, conifers, etc.). - Are also found in
gardens and flower beds, as well as on house plants.
- Tiny green, brown or black sucking insects, often found in groups;
they cause leaf yellowing and sometimes deformation.
- May transmit viruses.
- Rarely lead to the death of the plant. |
- Trim the shrub in question before
the treatment, if required.
- Water daily, if possible, using a powerful spray, in order to
dislodge the aphids.
- Foster the proliferation of predators such as ladybugs and
lacewings.
- Use the proper amount of fertilizer; too much fertilizer promotes
the growth of succulent tissue which attracts aphids. |
- Insecticide soap -
Mineral oil
- Acetamiprid |
| Tree-climbing insects: ants and
caterpillars |
- A number of species affected. -
Caterpillars feed on leaves.
- Ants do not harm trees. They are attracted by, among other things, the
honeydew excreted by aphids. In return, ants protect aphids from
their enemies. |
- Put a strip of tissue paper or cardboard
(about 10 cm long and coated with a sticky substance) or
sticky strips
sold in retail outlets around the trunk. |
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| Sugar maple borers |
- Sugar maples, as well as
red and silver maples. - Larvae that tunnel beneath the bark.
- Attack already weakened trees. |
- Fertilize properly. NB: There are few
corrective measures to be taken other than to use a bendable stick or
rod to kill the larvae when they are still in the tunnel. The little
mounds of sawdust on the trunk point to the entry of the tunnel. |
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Apple maggots |
- Apple trees. - Microscopic larvae that
leave grooves in the apple. |
- Pick up fallen fruit in order to avoid
leaving infestation sites intact. - Exercise damage control by using
traps: sticky red balls in the shape of an apple or sticky yellow bars
on which you place a red apple-shaped disk (5 traps per tree, hang 1.5 m
above the ground; lay traps after the petals fall). |
Permethrin |
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Scale insects |
- A number of species
affected. |
- When there has been a proliferation, cut
down the branches affected in order to reduce insect numbers. |
- Insecticide soap -
Pyrethrins
- Mineral oil |
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Bronze birch borer |
- Paper birch, grey birch and cutleaf
weeping birch. - Leaves dry and fall prematurely from the crown of the
tree.
- Uneven ridges (called gouting) on trunk and infested branches. The
larvae tunnel under the bark. |
- Since they usually attack weakened trees,
keep trees healthy with fertilizer and by irrigating during dry periods.
- Choose other types of trees, especially if the bronze birch borer is a
problem in your area. |
- Call a specialized firm. |
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Defoliator insects found on broad-leaved trees (birch
leaf miners, for example) |
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Generally, pesticides are needed only when
a tree is subject to a severe infestation many years in a row. |
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Maple gall mites (caused by tiny mites) |
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The “little warts” on the leaves do not
endanger the life of the tree. |
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Tent caterpillars (approximately 3 cm in length) |
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Remove them with a stick when they gather
in their nests late in the evening or during cool periods. |
Bacillus thuringiensis kurstaki (B.t.k.) |
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Leaf roller caterpillars or
leaf-rollers |
These caterpillars hide in rolled leaves.
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The leaves are easily removed by hand. |
Bacillus thuringiensis kurstaki (B.t.k.) |
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Aphids forming witchbrooms
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Often found on honeysuckle, these
small sucking insects (often pale green in colour) group together and
carry a virus causing leaves to shrivel and forming witchbroom. |
Witchbroom can be pruned. |
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| Diseases |
Apple Scab
(caused by a fungus) |
Apple trees.
Circular olive-coloured spots that turn brown and downy, found on
leaves and fruit. |
- Avoid vulnerable varieties (Gala,
Delicious, Jerseymac, McIntosh and Cortland) and choose scab- resistant
varieties (e.g.: Liberty, Jonafree, Prima, Freedom and Spartan, or
crabapples such as Dolgo, Evereste, Liset and Makamik). - Remove
leaves in autumn, thus getting rid of infestation sites for fungi.
- Reduce dampness by leaving space between plants.
- Trim the tree for better aeration. |
- Sulphur |
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Dutch elm disease (caused by a fungus
carried by small insects called native elm bark beetles) |
- Elms. - From mid-June to mid-July, the
leaves wilt, shrivel, become dry and turn brown. |
- Choose a resistant species. - Prune
well above the affected branches (2 m) and destroy them; if these
branches are big or if part of the trunk has been affected, cut them
down, remove the bark and burn it.
- After each time you prune, disinfect your tools with rubbing
alcohol or methanol. |
- Have very valuable trees treated by a
company specializing in such work. |
Rose tree diseases
(powdery mildew and
black spot) |
- Powdery mildew forms a powder on leaves;
they then become twisted and turn reddish in colour. - Black spot is
characterized by the presence of round black spots on leaves, which turn
yellow and fall off. |
- Use resistant varieties of rose trees.
- Reduce the dampness level by spacing the plants, and avoid watering
the leaves.
- Gather the dead leaves as soon as they fall in order to keep
infestation sites of this fungus from forming. |
- Sulphur - Copper |
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Powdery mildew of lilac
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Fungus on the top part of the leaves
generally appears during the month of August. |
Gather and destroy the leaves in the fall. |
No treatment is needed if the infestation
is minor. |
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Black knot found on cherry trees
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- The more quickly you remove the diseased
parts destroyed by this fungus, the less damage there will be.
- Also check neighbouring wild cherry trees which could contaminate your
trees. |
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Nectria canker (also called target canker)
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Often found on the tree trunk, this fungus
penetrates by way of a machine-made gash to the bark. |
It’s important to thoroughly protect the
latter. |
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Fire blight
Often found on sekuice trees (service trees) and from time to time on
hawthorns, apple- trees and cotoneasters (family of Rosaceae plants).
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Ask for resistant varieties when purchasing. |
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1 Follow the
instructions provided on the label of the product.
To learn about repercussions of active ingredients for human
health and environment, please see the table entitled “Relative
toxicity of the main active ingredients contained in pesticides for domestic
use used for green spaces"
(PDF file,
134 Kb).
|
Solutions to problems
of undesirable organisms affecting lawns |
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Harmful organisms |
Symptoms or damage |
Alternatives to pesticides |
Insects and
undesirable plants
See the section Control of the main indesirable organisms present in
residential lawns (in French only) |
| Diseases (fungi) |
| Dollar spots |
- Small round spots of yellow
grass appear in spring and fall. - Ideal conditions: excessively damp
ground. |
- Do not water. - Aerate and dethatch the
lawn in the fall.
- Enrich the ground with compost.
- Fertilize every week with small quantities of a nitrogen-rich
fertilizer in order to combat the damage caused by the disease. |
| Powdery mildew |
- Looks like white powder on
top of the grass, especially on Kentucky bluegrass. |
- Avoid watering in the evening: water
early in the morning. - Allow the ground to dry between watering.
- Apply fertilizer.
- Aerate the soil in the fall. |
| Other organisms |
| Mushrooms (with stems) |
- Often flourish in soil that is slightly
acidic and low in calcium. - Often found on decomposing vegetal matter. |
- Maintain a ground pH level that is above
6.5; spread dolomitic lime as needed. - Remove the mushrooms by hand,
in particular before cutting the grass in order to avoid spreading the
spores.
- Aerate the soil in the fall. |
To learn more about fighting against undesirable insects and
diseases, you can visit:
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How to create an
unfriendly environment for undesirable plants Learn to
recognize undesirable plants; their presence often speaks volumes about
the nature of your soil. |
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Undesirable plants |
Conditions in which they flourish |
Prevention and solutions other than pesticides |
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Common ragweed Giant ragweed To learn more about ragweed, you can visit Ministère de la Santé et des Services sociaux -
L’herbe à poux, ça s’arrache! (available in French only)
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- A sparse lawn. - Freshly-turned or
vegetation-free soil.
- New earth containing seeds.
- Vacant lots. |
- Having a thick, healthy lawn reduces the
chances that ragweed seeds will germinate. - Mow regularly.
- Pull out the plant before it flowers in August.
- Organize and take part in an anti-ragweed campaign in your area. |
| Poison ivy |
Consult the fact sheet
Poison ivy to know some more on this plant. |
- Digging and yanking to root out poison ivy is the most effective
means of eliminating this undesirable plant. By repeatedly working the
soil, you can usually succeed in getting rid of poison ivy.
- Whenever possible use a mulch (geotextile, bark shavings, wood
shavings, etc.) that will prevent the plant from growing again.
- Apply a herbicide whenever poison ivy has sprouted in places where
it is difficult to work the soil. Ask for advice about choosing the
right pesticide.
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| Broadleaf weeds |
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Plantain tends to grow in poorly drained
soil which has been trodden on by many people. -
Rough cinquefoil and red
sorrel tend to grow in acidic soil.
- Woundwort and ground ivy prefer clay soil.
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Knotweed and
European weed-sorrel flourish in compacted soil.
- Lamb’s-quarters takes root in a sparse lawn.
- Common mallow and purslane prefer soil with sparse vegetation. |
- Pull out the undesirable plants by their
roots. - Spread mulch.
- Keep your grass thick and healthy.
- Use ground cover (lesser periwinkle, pachysandra, etc.) in shady
places where the grass cannot grow densely.
- Spread corn gluten meal on a thriving lawn which prevents the seeds of certain undesirable plants from
germinating.
- Make sure that the pH level is between 6 and 7; lime as needed to
make the soil less acidic and thus less hospitable for certain plants. |
Mulch is used in vegetable gardens, in flower beds as well
as at the base of trees and shrubs in order to curtail the spread of weeds
and to ensure that the soil remains damp.
| |
Best organic mulching materials |
Mulch thickness |
| Vegetable gardens and flower beds |
Compost, leaves, sawdust, and lawn clippings |
2.5 to 5 cm |
| Trees and shrubs |
Wood chips or debarked chips |
5 to 10 cm |
Spread organic mulch on the soil surface; do not incorporate it into
the soil. Add a new layer of mulch as the old layer decomposes naturally.
Do you wish to eliminate weeds before planting or eliminate
those that thrive on grass-free surfaces (patio, garage walkway, etc.)?
Do your weeding manually by rooting out the entire plant. If
not, use boiled water to destroy undesirable plants or a thermal weeding
tool (for example, a propane flamer).
If necessary, use low risk herbicides such as acetic acid or
a mixture of capric and pelargonic acids. Don’t forget that all vegetation
is destroyed upon contact with these non-selective products.
House plants
Growing conditions for indoor plants are generally different
from those they would find in their natural (often tropical) environments.
It is therefore important to try to provide such plants with the light,
humidity and temperature conditions that they require so that they remain
healthy and better resistant to disease and insects. Start with the
following essential guidelines:
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When you purchase a plant, keep in mind the room in which
you intend to place it:
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Light is the most important aspect. Ideally, you should
be able to provide the number of sunlight hours needed. If not, at least
3 hours of sunlight is sufficient for most plants requiring full sun or
shade. East facing windows usually provide these conditions. For south
or south-west facing windows, place plants further away from the glass.
For north facing windows, add artificial light. You can also move your
plants around, depending on the season. Place them in south facing
windows in winter and north facing windows in summer. For example,
hibiscus requires at least 4 hours of direct sunlight per day, so a
north facing window would be inappropriate.
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Humidity should be 50 to 60%.
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Every plant has its own fertilizing and watering
requirements, and they can vary depending on the time of year. Keep them
in mind and remember that the key to successful plants is moderation in
watering. Most plants prefer that the soil dry out between watering.
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When you re-pot plants, generally in spring or as required,
use sterile potting soil and choose the appropriate plant-specific type
(cactus mix, African violet mix, etc.).
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When you purchase a new plant, check it carefully for
insects and disease. At home, keep it away from other plants for 3 weeks
and check it regularly.
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Avoid putting plants outside during the summer. If you do,
it is better to re-pot before bringing a plant indoors in the fall. Be
sure to (gently) remove all the earth and avoid damaging the roots. You
should also mist the plant fully with water or insecticide soap. Keep the
plant away from other plants for 3 weeks and check it carefully for
insects and disease. If the plant develops a disease or has insects,
remove the diseased portions or insects (with a cloth, cotton swab or
brush) and spray the foliage.
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You should generally check your plants every time you
water them. Place any diseased or infested plants in quarantine and treat
as required.
| Problem insects:
solutions house plants |
| Most common pests |
Alternatives to
pesticides |
Pesticides: a last resport1 |
| Aphids |
- Water with a powerful spray (e.g. use a
showerhead). - Insect sticky traps (yellow or white). |
- D-phenothrin and tetramethrin
-
Permethrin
- Pyrethrins
- Resmethrin
- Rotenon
- Insecticide soap
- Insecticide soap and pyrethrins
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Whiteflies |
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Insect tricky traps (yellow) |
- D-phenothrin and tetramethrin
- Permethrin
- Pyrethrins
- Resmethrin
- Insecticide soap
- Insecticide soap and pyrethrins
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Spider mites |
Prevention: spray foliage regularly |
- D-phenothrin and tetramethrin
- Pyrethrins
- Insecticide soap
- Insecticide soap and pyrethrins
|
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Thrips |
- Insect sticky traps (blue or yellow) |
- Pyrethrins
- Resmethrin |
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Scale insects |
Remove with an alcohol soaked cotton swab. |
- D-phenothrin and tetramethrin
- Rotenon
- Insecticide soap
- Insecticide soap and pyrethrins |
1 Carefully follow the instructions provided on the label of the
product.
Helpful hint
To avoid spraying pesticides into the air in your home, cover the plant
with a plastic bag and spray through a small opening. Or, even better,
treat the plant outdoors, weather permitting.
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A few definitions
Honeydew: Sweet sticky liquid
excreted by insects that feed on plant sap.
Back to text
Mite: Microscopic organism of the spider
family. The adult usually has four pairs of legs. Mites are not
insects.
Back to text
Mycorrhizal fungi:
Soil-borne mushrooms connected with plant roots. These mushrooms help
promote the absorption of mineral elements in the soil by plant roots
and in this way improve the plant’s nutrition.
Back to text
Nectar: Sweet liquid generally secreted
by certain flowers; it attracts pollinating insects.
Back to text
Pollen: Male reproductive element of
flowering plants.
Back to text
Spore: Reproductive structure
of fungi. Back to text |
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