NEEM PEACE
SCIENTIFIC NAME: Azadirachta indica
FAMILY: Meliaceae
INTRODUCTION
As recently screened on the TV Show 'Beyond 2000', more new ways are being discovered and researched into how medicinal and anti-pest constituents of the Neem tree can be fully utilised.
Not only does the tree yield the world's most efficacious insect repellent from the fruit kernels, and the leaves, the same compound 'azadirachtin' and its chemical analogues has now been shown to have systemic qualities far beyond those previously contemplated; it looks like becoming the world's first systemic biological pesticide!
Whereas the wood, and most other Neem products commonly available in South Asia are not yet on the market shelves in Australia, the demand - especially in Europe and the United States has reached a point where demand will soon outstrip supply, and plantations are already too small to supply U. S. needs. Vast semi-arid, and tropical land areas are now being planned for planting the Neem; exotic fruit growers would also benefit from having a few or more Neems, to be able to make their own pesticide brews as needed, and as advised by GTl, the German Aid Agency of the German Government - as advised in a free booklet to 49 semitropical and tropical countries.
Neem trees will grow and fruit well in dryland areas north of Rockhampton, but genetic variability means that they are highly adaptable to both the dry and wet tropics. Yields are best, and more pesticide is probably produced in the driest regions of the far north.
SPECIAL FEATURES
Unlike other 'fashionable crops' like babaco, aloe vera and jojoba that came and went in the 1970s and 1980s, Neem is a powerful 'stayer'. Not only is it a longlasting tree with a long history of being both a medicinal and pesticidal plant, new research now shows and confirms what ancient cultural groups in India first found out over 1000 years ago. These special features include the knowledge that we have at our disposal, after fruit and leaves are harvested, branches that contain the world's best-known natural dentrifice for the manufacture of toothpastes, plus an oil, 'neem oil' that is already India's most widely utilised oil for reading lamps and production of basic commodities, especially soap.
Whereas one cannot even locate Neem wood in the Australian market as yet on-the-docks or with Brisbane or Sydney importers of Asian timbers, the special class of hardwood represented by neem, that is a 'three-star' category wood, indicate that the tree has a big future market at the end of the day, 30 - 50 years after planting.
A recent all-Queensland survey of Neem trees planted and surviving in the ground in that state, revealed some 16,000 trees of average age 2-years, most of which will be or should be producing fruit by the end of 1992. The average planting size, whilst skewed by two large plantations of over 2,500 trees is in the vicinity of 250 to 440 trees per farm/property.
DID YOU KNOW? That the Neem tree has:
• An edible fruit, but with only a thin flesh, quite sweet, juicy pulp, yellow?
• A wild origin "reputed to be in or near southwest Burma?"
• The ability to withstand some frosts due to a very thick cork-like bark underlayer, in addition to easily surviving desert conditions up to 50°C?
• Now become the fastest-selling tree species for desert regeneration and land reclamation in desert regions of western Asia and sub-Saharan/ Saharan Africa, as recently reported by Ben Swane after his recent visit to Italy where much of the African demand is catered for by nurseries growing the young trees; (fastest selling plant species in Saudi Arabia and Iran, outselling Eucalypts!)?
• Become recognised across the world as being a truly revolutionary 'pesticide' producer, at the same time as not being a true-pesticide according to chemical registration principles so far established, because it (neemspray) has no killing ('cidal) properties - even though methylated spirits can and does kill some of the insects sprayed with it.
• A powerful ability to attract native useful insect species, such as the Lycaenid azure blue butterflies at flowering, predator microwasps around fruit maturity, a full range of cicadas and small psyllid-barkhoppers in addition to diverse microfauna that abounds under trees where leaf litter builds up quickly?
• A remarkable ability to root deeply into even rocky soils, so long as they are relatively well-drained, with strong taproots capable of reaching groundwater as deep as eight and maybe more metres, at the same time as reversing soil acidification in the upper layers (topsoil zone), as proven in parts of Nigeria over three years under trees up to 15 years old(World Food Crops J.) bring up soil-pH to neutral (pH=7) within that short period of time?
• Now become naturalised for multiple uses in over 49 countries bordering on the tropics, with the largest new plantations in India, Mexico and East Africa?
A NEW GENERATION OF BOTANICAL PESTICIDES
Rainforest tree species, and forest plants of all types are just starting to become 'exploited' for their natural chemistry, such as the ability of Neem to deter and repel so many insects. The neem tree just so happens to be the first 'off the rank' of all the Asian rainforest Meliaceae which characteristically have a strong ability to resist insect attacks. Long-lived species appear to demonstrate this ability more clearly, although this may be that they, like Neem, have taken a longer period of (millions of) years to evolve; this could be expected of many trees whose centre of speciation is in dense tropical regions such as Burma which have experienced no or negligible glaciation for hundreds of millions of years.
Whilst the Meliaceae family of trees, that includes cedars and mahoganies etc is typical of resilient tree families, there are others; and, no doubt like Neem numerous others species will soon come to light with further research into their anti-insect biochemistry.
The new generation of botanical pesticides will be characterised by zero-to-non-measurable mammalian toxicity, nil avian toxicity, combined with a complex capacity to baffle insects to the point where they cannot develop resistance to the chemicals used because they are not actually coming into contact with it. In the case of Neem whose active ingredient is azadirachtin, and its 10 or more analogues plus isomers, if and when an insect does contact or eat some chemical, genetic mutation is somehow precluded because the analogues represent too complex a set of chemical barriers to the insect's chromosome copying system. In neem's azadirachtin is contained the ability to upset an insect's hormone system before the insect's cells have time to adapt, a feature characteristic of only insect (Class Insecta) physiology); this ensures no mammalian effects/ impacts exist.
For some species of insect pest, Neem displays only repellency/deterrence; in others, repellence is combine with the stopping of feeding especially by larvae, and (most luckily of all) in a few species, anti-hormonal actions can take place independently or in tandem with both or either of the above. This makes Neem spray/s the most complex organic insect repellent known and developed. Organic protection for quality 'organic produce' (ref: NASA and Biological Farmers of Australia both recognise neem as a fundamental part of any successful organic farming operation.
WHAT CAN I DO WITH THE NEEM SPRAY AND TREES IN NORTH QUEENSLAND?
Table 1 shows a shortlist only of Australian insect and tick pests that Neem has been proven to be effective against. Of these, repellency against grasshoppers and leaf-miners, plus leaf-eating beetles/grubs have shown to be most consistently yielding 'pest control' in crops and orchards of far north Queensland. Organic farmers working towards full Certification of crucifer and herb and mango crops have been the most frequent purchasers.
Through systemic application around the base of the trees, it is potentially possibly to deter the majority of these invading pests, and be one step ahead of the chemical companies which have limited or no new chemicals to 'throw at' such noxious species.
Erinose Mite of lychees will be one of the next problems to be countered, but even this is potentially achievable, yet research has not yet begun. At DPIQ, based on a donated sample of a neem spray, Mareeba entomologist B. Pinisi proved that 100% control of banana weevil borer can be achieved in laboratory conditions (March-April 1992); a full field trial is now set to be initiated.
In lieu of generalised and applied research into all the insects likely to be controlled by neem azadirachtin, more local and regional orchard crop experiments are needed. Reports can be generated on standard forms for growers, for transfer of results to Entomologist and Senior Lecturer at the Univ. of Queensland, Dr. M. Rice.
We acknowledge the Entomology Workshop Pty. Ltd., of Indooroopilly, Qld. for some of the information in the above article, including Table 1
COMMON QUESTIONS re NEEM
Q. Is a Neem tree good enough to keep insects away from the house and vegie garden?
A. Probably not. One Neem tree by itself, and without crushing leaves and/or fruit regularly will probably not repel more than 25% insects.
Q. Are Neem trees good for the garden, if so why?
A. Yes most definitely. They attract a range of native insects which especially like their bark, inc. cicadas, psyllids and native wasps that feed on gum exudates from growing tips; insects that do not spread scale. Secondly the pH of notoriously acid Australian soils is brought quickly up to neutral (pH 7) within a short period of 2-3 years, as proven by research in Africa where Neems have been grown since 1926.
Q Do I plant the trees in shady, sheltered or open spaces?
A. Neem likes full sunshine for best results, but will perform through a mixed, not-dense canopy so long as it is not already much higher than the seedling you are planting.
Q. What soils are OK? Can I plant my Neem into clay soils?
A. Well-drained soils, including deep sands are good. Sandy loams with groundwater around 4 - 6 metres is probably best. Clay generally slows growth unless constant irrigation and pree-ripping is undertaken.
Q. How long until I can expect some seed, and what can I do in the meantime?
A. Under irrigation with some nutrient feeding (e. g. rock dust + mulch), good fruit crops can be expected in the third year. Fruit flesh is edible. Meanwhile, leaves can be harvested at the time of pruning or shaping the trees, and after slow air-drying, leaves need to be crushed to a powder, which, after soaking for 36 hours, will yield a weak azadirachtin spray; rate for dilution is approximately 1 litre of water to 125 g leaves fresh weight.
Q. Is it true that azadirachtin-Neem is the world's first truly 'systemic-biological' insecticide?
A. True, it is the first developed, systemic insect deterrent/repellent and the first one found to have such high level specific activity against insects (and to some extent the mite-tick families). Because it does not affect so many other forms of biota, but may influence some predatory insects, the active ingredients are revolutionary.
| Q. How are Neem seeds harvested? | Neem leaves, flowers and fruits. |
A. Neem trees bloom for the first time when they have reached the age of 2 to 3 years, and bear fruit at the age of 3 to 4 years. They normally produce fruit once a year, but in some moist zones, twice a year. The fruit of the neem can either be shaken off the tree, picked, or stripped from the branches. When ripe, it is yellow in colour, about 2 cm in length and oval-shaped. In the soft, sweet fruit there is a light-coloured seed of about 1.5 cm in length, containing one, or sometimes two, brown seed kernels. After harvesting the fruit, the ripe pulp should be removed as quickly as possible. In some regions, birds or fruit bats eat the sweet pulp, so that a log of clean seeds can be found on the ground.
Reference. Brochure published by the German Aid Agency GTZ, distributed to 49 Asian, African and American nations.
The neem tree (Azadirachta indica A. Juss) thrives almost anywhere in the tropical lowland, up to 800 m above sea level. It is resistant to extreme drought and grows where the annual rainfall is as sparse as 300 mm. Moreover, it grows very quickly and makes few demands on the soil fertility. The neem tree, therefore, grows in a wide variety of places. Hilltops and infertile, depleted land (e.g. eroded hillsides) are as suitable as stony, flat land or hard laterite. The neem tree may be used to line avenues, to border roads or fields and in mixed cultivation with fruit trees.
The average annual fruit yield from a mature neem tree is above 20 kg. Apart from insecticides, neem oil may be extracted from the seed; 30 kg neem seeds produce 6 - 8 kg oil. The resulting residue can be used to make insecticides in a similar way as from the whole neem seeds described earlier.
All parts of the neem tree can be utilized. Insecticidal substances are present in various parts of the tree; the highest concentrations are, however, contained in the seeds.
DATE: September 1992
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