Salannin, nimbin and meliantriol are other compounds found in neem.
Meliantriol's primary contribution to the Neem arsenal is its ability to block insects feeding.
Salannin also affects feeding.
The alkaloids Nimbin and its close relative Nimbidin have strong anti-viral as well as anti-fungal properties
Other natural compounds within Neem oil are also effective some to a lesser degree, while the significance of others are not fully understood.
1. Neem acts as a growth regulator interrupting the insect's growth cycle resulting in its death.
2. Its active ingredient has very low toxicity ratings, and no known insect resistance has developed.
3. Neem oil effectively controls more than 300 common pests
4. It causes insects to reduce or cease feeding.
5. Neem will prevent larvae from maturing.
6. It interrupts mating and egg laying.
7. It has the added benefit as being a useful fungicide.
8. It is virtually harmless to beneficial insects.
Not all insect pests are equally affected by Neem based pesticides.
Neem must be ingested by the insect to be effective. Because many beneficial Bugs , such as Bees and pollinators don't ingest sufficient foliage, they aren't effected much at all. Just so this is completely understood, Neem is toxic, even deadly to bees that are exposed to direct contact. Do not apply this product while bees are actively visiting the treatment area.
Spiders eat it , but for some reason it's not toxic to them and they continue controlling your insect problems. Predators such as Lady Bugs do not eat enough plant matter to be effected by the Neem treated foliage, they do eat the bugs that ate the Neem but are not significantly effected - that's good. They will however , be effected by direct contact the same as Bees.
Neem Safety, Neem Side Effects And Neem Toxicity
Neem oil as a foliar spray is most effective when applied to younger plants. The oil, being a natural compound biodegrades faster than man made chemicals, its effectiveness is limited to 3 - 4 days and needs to be frequently re-applied. It is water soluble, however, When diluted with water it's effective span is drastically reduced so it is best used straight or with minimal dilution. Actually, The highest concentration currently available to home gardeners is about 3%, so product packaging should give information on dosage.
Some Garden Gurus have suggested using Neem Oil as a soil drench. Take note that Neem oil is not a systemic insecticide. It is similar to a contact killer but must be ingested by the insect to be effective. Because many beneficial Bugs , such as Bees and pollinators don't ingest sufficient foliage, they aren't effected.
As a soil drench, it is not very effective against insects. Theoretically, the neem enters the plant’s vascular system, insects ingest it during feeding. In reality, by the time the compound works it way through the soil, into the plants vascular system and than into the bugs it's effectiveness is long since expired.
As a foliar spray it causes insects to reduce or cease feeding, will prevent larvae from maturing, interrupts mating and egg laying. If sprayed directly on the insect, like other horticultural oils it coats their body surface, prevents respiration and hence kills them.
Neem oil as a fungicide
Neem oil fungicide is useful against fungi, mildews and rusts.
It is suggested commonly as an effective fungicide primarily for the prevention of various fungal and bacterial diseases such as
mildew and scab
The alkaloids Nimbin and Nimbidin found in Neem have strong anti-viral as well as anti-fungal properties. There are better more effective products on the market in the realm of fungal and bacterial protection, however - If you are already using neem, or plan to use Neem for insect control, it has the added benefit of serving as a fungicide. If you already have fungal problems closing the door once the animals are out is not very useful. Neems primary benefit is as an insecticide not a fungicide. It is also more useful as a preventative measure rather than a cure for existing fungal problems.
Other limitations on neem as a fungicide is that it breaks down rapidly in nature. Extremes of temperature, rain and other environmental factors make it necessary to reapply it frequently.
How to Apply Neem Oil Foliage Spray
Neem is not good for all plants, some can be damaged or killed by it if applied too heavily. It's advisable to test a small area on the plant, wait a day and check for any leaf damage. If there is no damage, the neem is safe to use on that plant.
When you spray Neem oil, it should be done early in the morning or late night, when the beneficial insects are the least active. That way you would avoid contact with beneficial insects, only the bugs that eat the foliage are effected directly. Dawn or dusk are also advantageous as you are avoiding direct light which prevents foliage burning and allows the neem to seep into the plant.
Neem oil insecticide should be applied about once a week. Apply it as you would other horticultural sprays, making sure the leaves are saturated - completely coated.
Dilution rates vary and some products do not require dilution so be sure to check the label instructions.
Baking soda aka sodium bicarbonate is a cheap and effective fungicide it is used for controlling powdery mildew and other fungal issues. Combined with Neem oil the two compliment one another's effectiveness.
1 gallon water
10ml neem oil
10ml soap (Dawn, Ivory or castille soap)
2 tsp baking soda
Do not rely too heavily on persistent use of baking soda, its sodium component will accumulate in the plants and soil, over time it can become toxic to plants.
|Organic Pesticides||Herbal Pest Control||Companion Planting|
|Magnetism And Plant Growth||Organic Gardener's Handbook of Natural Pest and Disease Control|