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Gardening Articles for week ending 8th OCTOBER 2005
It is disheartening to find that a shrub or plant is being attacked by numbers of some insect pest. It maybe a number of aphids on the new growths of your roses, a swarm of adult whitefly exploding into the air when you touch a tomato plant,
or the change of leaf colour on a rhododendron, with the leaves becoming silvery coloured, due to thrips. Once discovered, a maternal, protection attitude comes into play and you want to zap these critters that had the cheek to feed off your plant!
Its a predatorial universe and so now you become the predator.
You go to the garden shed and check out your arsenal of killing substances for a solution. Your first reaction is likely to find the deadliest poison and do battle.
Not a good idea as not all chemical poisons work on all insect pests and even if they do they are dangerous to you and the environment. Certainly not something that you want to soak over a food crop that you are going to eat sometime later on. Many chemicals effect the overall health of the plants also, so even if you kill the pests present, you weaken the plant and lay it open for further new attacks.
It is far better for all concerned to use something that will do the job and have the least amount of side effects.
A quick knock down is Key Pyrethrum, derived from Chrysanthemum flowers, affects the nervous systems of insects and fish. Can be used at only 1 ml per litre of water as trials showed that the rates of 1ml to 5ml per litre did not have a significant difference in the kill ratio. Pyrethrum is quickly broken down by sunlight (UV) so should only be applied very late in the day prior to dusk for best results.
Neem Oil is also naturally derived from the kernels of the Neem Tree. It does not actually kill insects, except for the oil-smothering action that affects thrips, scale and mites. Instead it prevents many insects from feeding or maturing. This means that they die of starvation or the inability to grow. These conditions happen when an insect chews or sucks on a plant that has been sprayed with Neem Tree Oil, which could be called Neem 1500EC as it contains 1500 parts per million of the most active ingredient, Azadirachtin. (can vary as nature is not constant) Neem Oil is also affected by UV but last much longer than Pyrethrum. Usually effective for several days to over a week. By mixing either MBL (Magic Botanic Liquid) or Raingard with the oil, shields the active properties from UV giving them a longer active period.
Another point is, never leave your Neem Oil bottle in sunlight as even with a thick, solid plastic bottle, shelf life can be reduced. Store in a unlit situation.
Now for some more interesting aspects, Say you have a rhododendron that is very tall, difficult to effectively spray, and it has thrips. Cross Hills Rhododendron Growers found that if you soak a felt pad in Neem Oil (undiluted) and wrapped the pad around the trunk of the tree, the oil would be taken into the tree’s sap line and kill the thrips, all over the plant. In fact Cross Hills made special felt strips for this with one side covered in plastic to prevent rain diluting the oil. This control is best used about November when the thrips become active with the warmer weather.
If you use your own felt just put glad wrap or similar over the felt and hold all secure, with a couple of drawing pins. Likely there are many other trees for various insects that the same principals can be applied, dependant on the type of bark the tree has.
Some barks may not allow the oil to penetrate.
Which takes us to another interesting aspect, Neem Tree Granules and Neem Tree Pellets. When the oil is cold pressed out of the Neem kernels the remaining material is called Neem Cake in India. This is the bits of the crushed kernels which can be used as they are or placed into pellets like sheep manure pellets.
The Neem Cake contains some of the Neem properties and for countless years orchid growers in India have been placing these granules or pellets into their orchid’s mix.
They find that their orchids are kept fairly free from all insect pests as a result.
In potting mixes or orchid mixes the effects last about 6 months. In soil where there is a lot more micro organisms breaking down the crushed kernels, about 2-3 months.
What transpires is the Neem Cake breaks down (decays) releasing the Neem properties. These properties are taken up by the roots of the plant and translocated through the whole plant. An insect that lands on the foliage and sucks or chews, gets a dose of Neem and stops eating waiting to die. Populations don't build up and spraying is not needed or greatly reduced. Its a neat first line of defence and ideal to apply to plants before a problem happens. If you have a problem then spray with the Neem Oil and Pyrethrum first then place pellets near the base of the plant or on the drip line.
Cover the pellets/granules as they do go mouldy. Alternatively if you are planting out seedlings, plants, bulbs or tubers place a few in the planting hole.
Insects that attack the roots of plants such as grass grub, root mealy bugs and nematodes can also be affected by the placement of these natural products.
How effective are these treatments? I was told that a 20 foot tall Cabbage Tree thus treated, fixed the Cabbage Tree Moth’s caterpillars way up in the foliage.
I have used the granules around the base of tomato plants in a glasshouse and have not been bothered with whitefly problems. In the same glasshouse I have had less success with Cucumbers and still had to spray for whitefly about every 6 weeks or so.
The difference between the two plants is because when a plant takes a substance into itself, it immediately begins converting the substance to carbohydrates or sugars. Some plants are more efficient at this than others. So Neem granules/pellets effectiveness will vary from plant to plant but at the same time can reduce the amount of spraying in many cases. The Neem kernels being organic are also a great soil conditioner and do supply a natural amount of food (NPK) to the garden plants as well.
Its no of no surprise that in India they refer to the Neem Tree as the ‘Wonder Tree’.


. If unsure phone me on 0800 466464 (PNth 06 3570606)
Email wallyjr@gardenews.co.nz
Web site www.gardenews.co.nz

Garden Pages and News at www.gardenews.co.nz
Shar Pei pages at www.sharpei.co.nz

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