Natural Insecticides and Fungicides

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Weedguru Higher
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Natural Insecticides and Fungicides

Post by Weedguru Higher »

Natural Insecticides and Fungicides
By Corto Malteze

Here's a list of non chemical, natural insecticides and fungicides:

A few definitions:

Decoction or Brewing:
Put plants in a water pot for 24 hours before you boil them for 15-20 mins. Put a lid when its cooling off.

Put the plants in the water and boil. Wait 24 hours after boiling.

Fermented slurry: Leave plants in a water container in the shade for 1-2 weeks. Don't cover with a lot of water. Mix daily. You can also put the plant in a permeable bag (mesh) in the bucket to avoid straining.

Place plants in a water container in the sun for 4-5 days.

Leave plants in water 2 or 3 days to avoid fermentation.

Handle with care (protect eyes, skin, wash hands after ...). Don't spray insecticides on your plants if they are fine. Inspect your plants closely (under leaves...) for miniature spiders, aphids, caterpillars, small white flies etc... Little white, grey moths (they make white webs) are ok -here-, and often settle on my plants. They're my little buddies. Preventive insecticide is not used for mj, a usually insect resistant strain. Fungicides can be used preventively if your region gets rainy, cold in the Fall. Spray in the morning so it's not wet at night (mold).

Some foes:


Spider mites:

Natural Insecticides and Fungicides

1. Nettles

Fermented Nettles slurry (fertilizer tea and fungicide, repellant)
(fresh -very smelly to brew- or powdered) repels aphids, acarids, prevents mildew, brown rot. Nettles are very ecological and less harmful to other life than stronger natural insecticides like Pyrethrin.

Take 1 kg of nettle plants (without roots), place in 10 liters water for 10-15 days in the shade (18 ° celsius for the reaction to work best). Mix every day (without lid). It's ready when it doesn't make any more bubbles. Strain. Use the liquid. Nettles feed the plant with N + trace elements and protect it from diseases too ( more preventive than curative). Use esp. in veg. period every 3 weeks because of the high N. Store in shade (basement) up to 1 year in a closed container (so fermentation doesn't start up). Dilution 5% for foliar feeding. 20% as tea.

Nettles slurry (insecticide and fungicide spray): Place 1kg nettles in 10 liters water for 12-24 hours. Dilute 5% foliar, 20% for tea. Spray on your plants if insects on them. Use every 15 days.


2. Garlic

Garlic insecticides are more efficient in decoctions than in infusions. They won't make the bud taste like garlic! Use mainly as a curative (on the plant and insects if they appear). Spray on plants infested with spider mites, whiteflies, aphids, acarids, thrips, kills caterpillars too.

Garlic insecticide decoction
(add black pepper if you want):

80-100g garlic for 10 liters of water. Blend the garlic with some water, place all in the 10 liter recipent, cover and let sit for 24 hours. Boil for 15-20 mins. Filter through cheese cloth or a strainer. Add a few drops of liquid soap to make the mixture adhere to plant leaves and insects. . No need to dilute.

Smaller proportions:

Place a clove of garlic in a blender and add 500 ml (2 cups) of water. Blend until smooth. Pour the liquid into a container with 2 liters of water, cover and let sit for 24 hours. Boil. Filter through cheese cloth or a strainer. Add one or two drops of soap.

Other garlic recipes:

Garlic concentrate :

- grind 2 garlic bulbs
- Cover with 4 TBS oil.
- Soak for 24-48 hours in 4 liters water + 2 tsp liquid soap.

Dilute 1 liter for 20 liters. Spray in the morning. Rince.

Garlic/Black soap/Pepper insecticide:

- grind 2 garlic cloves
- grind 1 oignon
- 1 TBS ground Cayenne pepper
- Place in 1l water. Boil for 1-2 hours.
- Add 1 TBS black soap.
- Ferment for 1 week
- Strain
- Use in spray.

Garlic/Onion infusion:

Grind 50 g of garlic and 250g onions with skins. Put in 10 liters of already boiling water for a few minutes. Leave alone for 12 hours. Foliar spray without diluting.

3. Neem oil

Neem oil is both preventive and curative. Ecological. Many trace elements and nutrients for your plant. Against acarids, aphids and mildew. Does not kill bees and lady bugs etc... (Lady bugs eat aphids naturally). An efficient neem oil contains minimum 1600 ppm azadirachtine (check on bottle).
Neem blocks insects' appetite, they vomit (so don't eat your leaves), and neutralizes the reproduction system of female insects (so numbers don't increase). Most bugs aren't killed with neem oil. Only mosquito larvae, fruit flies etc... die. Contact with local insects doesn't kill them but repels them (they go throw up somewhere else!). However, the oil can burn your plants' leaves with the sun. So spray in the morning (before sun), rince after 15 minutes.


4. Easy Recipes

Soap insecticide:

- Put 1 tsp of liquid soap in
- 1l of boiling water for 5 minutes.
- Spray.

Black pepper insecticide:

- grind 30 g. of black pepper
- Place black pepper in 1l of boiling water.
- Let simmer for 30 minutes.
- Spray.

General Homemade insecticide and fungicide:

- 1 liter water
- 10-20 ml soap
- 10-30 ml baby oil
- 10-20 ml baking soda (against fungi)

Use in the morning. Rince before sun comes (excess oil can burn).

5. Uncommon recipes

Horsetail decoction:
a natural fungicide. One of the only natural ones against Botrytis which can attack mj if too humid,wet.

Place 1 kg horsetail in 10 liters of water for 24 hours. Boil 15-20 minutes. Let cool off with lid. Leave 12 hours. Strain. Dilute 1 to 5. The combination of nettles + horsetail is an excellent insecticide and fungicide.


Rhubarb decoction: Kills aphids. 5OO g rhubarb leaves (in strips) in 5l water for 24 hours. Boil for 30 mins. Strain. Foliar feed undiluted.



Wormwood decoction:
Against aphids too. Place 250 g dried (2,5 kg if fresh) wormwood in 10 liters of water for 24 hours. Boil. Strain.


Matches: Place a few matches upside down in your soil. The sulfur in the matches repels aphids.

Garlic, Oignons:
Place them whole on your soil.

6. Fungicides

Against mildew
and bud rot spray baking soda solution (1TBS in 4 cups of water, add a few drops of liquid soap so it sticks), 10 % milk solution, horsetail decoction, neem oil, nettles, chamomile flower infusion.

Powdery mildew:


Bud rot:

7. Stronger, natural "last resort" insecticides:

Pyrethrin. It paralyzes the nervous system of insects. It is a curative treatment because it doesn't last long (rain, sun breaks it down).
Make sure the pyrethrin used is a natural extract. Do not use synthetic pyrethrin (cypermethrin, alphametrine...) and a powder called piperonyl-butoxid. Unknown side effects possible.
Use against acarids, aphids, white flies (aleyrodes)...
Warning: this is also deadly to lady bugs, bees, batrachians, fish and other insects touching it. So use it carefully. Doesn't kill mammals (!). Combine Pyrethrin and Rotenon for a very powerful curative spray. (one of the strongest before chemicals).

Bacillus Thuringiensis
is an age old excellent insecticide (natural). Against many insects and caterpillars. Curative. It is a combination of several bacteria. B.T is also known as Bactospein (in that case it contains natural pyrethrin: avoid). Advantages: It can be used in hot weather and stays longer than pyrethrin. The bacteria goes inside the caterpillar and kills it: radical. Some of my spots are close to caterpillar nests. I'll cut them off from the trees soon (gross). I might need this if my plants are invaded.

Mj eaten by caterpillars:
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