Some common materials that can do double duty as non-toxic pesticides:
- uncoated aspirin to fight mildew, black spot and more. Dissolved in water.
- baking soda (really useful!) prevents fungus spores from invading plants.
- boric acid or borax wipes out ants, roaches and more.
- canola oil works to smother insects and as a surfactant but any vegetable oil that isn’t too heavy will work – I like Trader Joe’s grape seed oil
- chili powder is used as a pesticide and a repellant
- cinnamon powder is useful as a an anti-fungal and anti-ant
- corn gluten meal inhibits seed germination (or at least it has in studies)
- Epsom salts provide a shot of magnesium and help promote growth of flowers and foliage
- essential oils, when mixed with water, help defer feeding and work to eliminate pests
- fish emulsion & kelp wonderful organic fertilizers that promote healthy plants
- flour, white but not self-rising, can be sprinkled on plants plagued by grasshoppers
- honey is a sure-fire lure for ants
- isopropyl rubbing alcohol, the 70% stuff, desiccates and destroys insects – if a bit tedious to apply
- molasses, good ol’ blackstrap or horticultural grade, jumpstarts microbial action and feeds beneficial insects – can be used to attract harmful insects into traps
- petroleum jelly can be used as a sticky barrier (around a tree trunk for example) to prevent access for undesirable insects
- liquid soap – NOT detergent! (almost all “dish soaps” today are really dish “detergents” and they are more harmful to plants and not as effective as insecticides – you will have to seek out Dr. Bronner’s or any other pure castile soap) can be used as a surfactant or as the active ingredient against many pests, insects and fungi alike; liquid soap is the basis of many home-made pesticides because it works to allow other ingredients to blend together (emulsify). You can have a bucket of soapy water in the garden in which to dump insects and help them die in the cleanest of ways.
- Tabasco sauce can be used as a pesticide and repellent (I like to tell about the time Grandpa used a syringe to inject Tabasco sauce into the watermelon closest to the road, it works to repel even human pests!)
- vegetable or mineral oil destroys insects and can also double as a barrier
- vinegar, either apple or white, buy whatever is less expensive, fights fungus gnats, can be used to kill some weeds and destroys pests – I use a solution 50% vinegar with water to kill ants when they invade my home or the greenhouse, as they often do.
- white glue is very useful to seal pruning cuts – especially roses against the rose borer which is a significant pest around here
GENERAL NOTES ON HOME-MADE PESTICIDE APPLICATION (also valuable for commercial sprays)
Test your spray first on a small portion of the plant before applying it to the entire plant. I mean, it should go without saying that you’d rather knock the pests off and not kill the plant.
Always, always, always use soap not detergent – you may not know the difference but your plants will.
Spray early in the morning, on a foggy day or, if you’re not an early riser, later in the day. (Early morning IS the best, but if you, like me, just can’t seem to get around early enough, late evening might be your only opportunity.) Do not spray when the temperature is at, or soon will be at, 85 or higher.
Wear rubber gloves when spraying – especially those sprays containing peppers, alcohol, citrus concentrates, mint oils or any other material that could irritate skin.
Do not spray when the wind will not allow you to control the destination of your spray.
Thoroughly examine the plant to be sprayed right before spraying it, specifically looking for beneficial insects or their eggs.
Most mixtures will require consistent agitation to keep the ingredients evenly mixed, so shake as you go. So to speak.
Make sure all of your solutions get on to the leaf undersides as well as the tops.
1 t Tabasco sauce
t liquid soap
Shake mixture well and decant into sprayer.
Tabasco, straight, can be used to discourage rabbits and other omnivores from chowing down on tender shoots. Test to make sure the tender shoots won’t themselves be “prevented.”
BASIL SUN TEA
1 hand full fresh basil leaves and stems
1 large glass jar – at least ½ gallon – with water
Put the basil in the jar of water and set in the sun for a few days; strain out solids and store (out of the sun) in a capped container until you need it. When using it, decant into a sprayer and add teaspoon liquid soap and shake well before using. A poor use for basil in my book.
RED PEPPER WRECKER
2 T red pepper
6 drops of liquid soap
1 gallon water
Allow the mixture to brew overnight. Stir thoroughly before spraying. Repeat about weekly to protect the Crucifers – cabbage, kale, broccoli, Brussels sprouts and cauliflower - from destructive critters.
¼ cup buttermilk
2 cups wheat flour
2 ½ gallons water
Shake the ingredients all together thoroughly and spray on plants infested with spider mites.
2 garlic cloves
1 quart water
t liquid soap
For plants with fungal or bacterial disease and rash outbreaks of vampires in your garden, puree the garlic in a blender on high for a minute. Slowly add the water and continue blending for about six more minutes. Strain, into a storage container adding the soap (adding the soap while blending is NOT recommended) and cover tightly.
To use, mix one part garlic soup concoction with ten parts water in a sprayer. I have read that scientists have discovered that garlic leaves can be used in place of the garlic bulbs and do the same duty; so you can use two handfuls of leaves and keep your bulbs for eating.
HEALTHY HOLLYHOCK SPRAY
1 ½ t baking soda
1 T canola or other light oil
½ t liquid soap
½ cup white vinegar
1 gallon water
While this says “hollyhock” it is useful to spray on any rust-prone plant – and in our area that includes roses. Blend the ingredients and decant into a sprayer. Shake thoroughly before and during applications, applying weekly to the whole leaf on susceptible plants. If you have diseased foliage, remove it and send it away – do not compost unless your are certain your compost is hot enough to kill the spores.
TAKE TWO ASPIRINS AND DON’T CALL ME
2 uncoated aspirins dissolved in one quart of water can be used as a foliar spray to deal with fungus infections, which include black spot, mildew and rust – all popular here.
1 T canola, mineral or other light oil
1 t baking soda
1 gallon water
Cornell published this as a remedy for fungal blights on tomatoes and potatoes. Shake thoroughly before using.
2 t baking soda
2 quarts water
½ t liquid soap
Keep handy in sprayer and shake before using – this is especially useful with powdery mildew or black spot – two fungal infections almost all roses get in Southern California.