For those who may be interested - my 2 satang on neem pest control products, Written for my California customers and associates, but much of the info applies to Thail growers:

Neem products have become wildly popular and in-demand as organic-program-compatible, less-toxic alternative to hard-chemistry pesticides.  But there are huge misconceptions and disappointments due to incomplete and misleading information available, even from professional crop advisors, nurserymen, tree and landscape professionals, and applicators.  The information is coming in but not everyone is getting it right.  You will undoubtedly come up against questions on neem products, uses, effectiveness and application specs.  

 

I'm not an authority on the science of it, and mine is not the last word, but I have been using neem since I lived and worked in agriculture in India in the early 70s.  Azadirachta indica is a beautiful tropical tree with many uses. There was a neem tree in my front yard on the edge of a village in Tamil Nadu, and I noticed that it was about 10 F degrees cooler under that tree. (That's a big deal in southern India where there are three seasons, hot, hotter and hottest.)  The local villagers would stop by and break off 1/4" diameter twigs to chew and fray the end to use as a toothbrush; it has plaque control and body cooling properties. The organic farm where I worked used neem as a pesticide, so my exposure was to traditional culture going back centuries, as well modern IPM.  My interest and love for neem started back then.

 

I’ve been in communication with a primary neem products researcher in India, a PhD entomology professor out of Bangalore Ag University. 

Here’s my two cents to the best of my understanding:  

 

In the US there are three primary categories of neem products, with several variations: 

 

Azadirachtin concentrates are extracted from neem seed oil. Aza products are insecticidal, miticide, nematicide (nematodes), but not known as fungicidal. There are no plant diseases listed on Aza products labels:   Azatin, Azamax, Azaguard, Azatrol, Azasol and Neemix as examples. They have Azadirachtin listed as the active ingredient, usually 1% to 4%. This is not the same as "neem oil". Azadirachtin is a highly concentrated form of the most potent of the many substances in the neem oil biochemistry.

 

Many of the products are OMRI listed because they biodegrade rapidly, but that does not mean they are without risk to the applicator. Azadirachtin poisoning is become an issue with the increased use in the cannabis industry.

 

Azadirachtin can go systemic or at least translaminar, but it should not be promoted that way because not all plant species will translocate all formulations in the same way.  Only Azasol from Arborjet, (Soluneem in India) is water soluble and can be soil applied for root uptake or stem injected with specialized equipment. 

 

70% Neem Oil on the other hand is not an Azadirachtin concentrate product. It is the residual oil substance after the Aza has been extracted. It relies on the horticultural oil properties, as well as the relatively dilute chemistry from neem seed oil, not the highly concentrated Azadirachtin.  

70% neem oil (clarified hydrophobic extract of neem oil) has insecticidal, acaricidal (miticide), and fungicidal properties. It is similar in action to petroleum-based horticultural oils, with the added benefits of the incredible neem biochemistry with insect repellent properties.  70% Neem Oil labels list soft bodied insect pests and some plant diseases (ectotrophic plant pathogens such as powdery mildews and rusts), which Aza products do not.

 

Monterey 70% Neem Oil and Garden Safe Neem and others are common on garden center shelves, Triact70 from OHP, Trilogy from CertisUSA, are available to professionals and more so now to the general public.  Azadirachtin products are much more expensive than 70% neem oil.  

 

Neem chemistry has not been synthesized and is not likely to be, due to the complex natural biochemistry. And neem products are likely to get much more expensive, due to a pervasive insect-vectored fungal disease (Phomopsis azadirachtae), Neem Tree Dieback/Blight, prevalent and advancing in some of the primary neem plantation areas of India and Africa.

 

100% neem oil sounds good and some people think pure is better. But from my experience the 70% Neem Oil is more effective and plant friendly and doesn't coat and clog sprayers like the 100%. The emulsifiers are important for mixing and dispersing. 100% is more likely to be unevenly distributed and burn foliage. Neither should be applied to soil. 

 

Choice of product or products for a tank mix or stem injection will depend on the pest or disease, stage of life cycle and level of infestation or infection, budget, and products available to the applicator. 

 

One of the biggest issues that many gardeners and professionals don’t understand and therefore get disappointed and say neem doesn't work: Neem like many other bio-pesticides is not a knock-down insecticide like the hard chemistry synthetic products, insecticidal soap, or botanical pyrethrum, and there is only a few days residual effectiveness.  Neem should be thought of as preventive or very early intervention, not curative for an advanced active pest infestation.  And every product label clearly states, it has to be applied every week for a high pest pressure situation, or every two weeks for general purpose prevention. It has repellent, anti-feedant and reproductive disruptor actions, but not much knock down effectiveness.  So, people use it once and expect to stop an infestation in its tracks, and it doesn't work that way.

 

In Thailand there are Aza concentrate products available, and 100% neem oil, but I have not seen 70% neem oil that is prevalent and widely used in the US. Hope that helps.