would like to know of plants containing pyrethrum please so I can
get rid of bugs naturally.
(Tanacetum cinerariifolium) is the name of an aromatic plant
of the daisy family that typically sports feathery foliage and white
daisy flowers with yellow centres. The closely related T. coccineum
is also known as pyrethrum but has less impact as a natural insecticide
than its cousin, T. cinerariifolium.
The natural insecticidal
properties contained in pyrethrum are called pyrethrins, and it
is these components that are extracted and used commercially in
products such as garden sprays, flea bombs, fly sprays and the likes.
The flower heads are either dried and powdered or the oils are extracted
from within the flower.
Pyrethrum sprays are
excellent for use against sap sucking insects, such as aphids, woolly
aphids, spider mites, thrips, scale, whitefly, and other pests including
caterpillars, earwigs, leaf miners, beetles and slaters.
You can make your own
spray or dust recipe by drying the flower heads (picked shortly
after blooming) on sheets of newspaper in direct sunlight
the quicker the drying process the higher the pyrethrin percentage.
Once dried, finely grind the flowers using a mortar and pestle,
then sprinkle the powder over your plants.
To make a spray, mix
half a cup of coarsely ground flower heads (dried) with 1 litre
of boiling water, leave to cool (about three hours), strain, then
add a teaspoon of pure soap. The soap allows for better leaf coverage
and increases efficiency by a factor of four. Apply the spray immediately
Note, however, that pyrethrins
are also toxic to bees, so make sure you spray early morning or
in the evening when bees are inactive.
The effect of pyrethrum
is immediate. It works by paralysing the insect or bug and killing
it, but if the solution is not strong enough it will simply stun
the insect, allowing it to recover again in a few hours time. If
this is the case, treatment will need to be repeated with a stronger
Pyrethrum breaks down
in sunlight, therefore it gives only a short-term protection of
about 24-48 hours. It will also need to be reapplied after rain.
Feverfew (T. parthenium)
is also a good insect repellent and contact insecticide that contains
pyrethrins and can be used in place of true pyrethrum (T. cinerariifolium).
A feverfew spray can be made as above (using 2 cups of ground dried
flowers), and a dust recipe can also be made as for pyrethrum. Some
say that feverfew is the perfect deterrent for bugs, keeping pests
away from all plants nearby.
by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor
of Resource Management.
with permission from NZOOM Home and Garden content,
from the previous
The views expressed here are not necessarily those of the RNZIH