[OGD] Neem

2006-06-28 Thread mhach


Dear All-

I have tried Neem Oil with some mixed results. Although described as a "safe 
insecticide" there is an immediate assumption that because it's natural it is 
harmless. The odor of neem can be a strong irritant to some people and can 
especially irritate sinuses and eyes if there is prolonged exposure in a 
confined area. People who have problems with chemical sensitivities on their 
skin should take precautions as well. I have also seen people react to the oil 
if it has been allowed to remain on the skin for periods of time. 
The active chemical in Neem has been supposedly extracted and is sold in some 
commercial insecticides (eg. Azatin) When Azatin was used there were some 
plants that exhibited phytotoxicity over time. It is unsure whether it was 
because of it being an oil or the chemical itself. Some plants with thin leaves 
(Phaius, Calanthe and some Lycaste) didn't particularly enjoy it either. It was 
certainly something that was very noticeable in periods of higher temperatures.
In my professional opinion the results were mixed for controlling mealybug and 
broad mites. I find that there are many other "safe" insecticides that are just 
as effective. Even something as simple as a solution of a detergent/dish soap 
provided similar and in some cases superior results than neem did. 

Marc


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[OGD] Neem Oil, by Susan Taylor

2006-06-27 Thread viateur . boutot
Interesting note on neem oil :

"Systemic for Orchids

Neem oil has been used for generations in its native habitat of Southeast 
Asia for insect control. It is non-toxic to mammals and can also be used as 
a systemic when used during watering of plants. It is toxic to insects when 
sprayed directly on them, works as a growth inhibitor for nymphs and when 
used as a systemic causes the plant to become unattractive to sucking insects.

As a result of a sudden eruption of scale in my greenhouse, I decided to 
try it and see if it is as good as advertised. What you want to buy is the 
"Pure Neem Oil" which is only allowed to be labeled as a leaf polish. Many 
nurseries carry it and most online orchid vendors have it if you cannot 
find it locally. It is relatively expensive, around $9.00 for 8 ounces or 
.25 litres of oil. However, you only mix four tablespoons or 20 millilitres 
per gallon or 3.75 litres to apply the oil.

The first applications should be to every leaf, under every leaf and on the 
top of the medium of every plant. This is consistent with any kind of pest 
control measure, so it does not make Neem Oil any harder to use than any 
other insecticide. Since it is non-toxic to mammals, it is not necessary to 
wear protective clothing or eyeglasses or rubber gloves. In my opinion it 
is almost worth it not to have to gear up just to use the product. A couple 
of words of warning … it doesn't smell terribly good, somewhat musty. And 
it is one of those smells that lingers for a while. You will want to wash 
your hands and change clothes after you spray plants. Also since it is an 
oil, it is not good to apply when the temperatures are too warm or sun is 
directly on your plants. Early morning is best.

Most sources suggest that the oil will last longer if kept in a 
refrigerator but it will solidify at that temperature. I keep mine in a 
sealed plastic bag and take it out a couple of hours before I want to use 
it. It also will not keep once it is mixed in water with a teaspoon per 
gallon of liquid soap. On the bottle I purchased it says to use it within 4 
to 6 hours, other sources suggest up to 8 hours. Anything that is left over 
can be used to pour in your pots to be taken up as a systemic by the roots.

To take control after an infestation of any kind of insect spray thoroughly 
ten days apart. Include all surfaces in your growing area if possible. For 
systemic protection use Neem Oil at the same strength in water once a week 
for four weeks. As always, be sure to follow the instructions on the 
container for amounts to use and any safety recommendations."

source : http://www.bellaonline.com/ArticlesP/art44070.asp

*
Regards,

VB


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