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Gardening Articles for week ending 8th
BUG FREE PLANTS
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
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 trees
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
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 orchids 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
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 Moths
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
Web site www.gardenews.co.nz
Garden Pages and News at www.gardenews.co.nz
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