In East Africa, the mature pyrethrum flowers are picked by hand,
sun dried to remove moisture and sent to a processing plant for
extraction of the active ingredient - pyrethrins, a mixture of six
closely related esters.
In Australia, the flowers have been bred to synchronously flower
so they can be mechanically harvested. As in Africa, the flowers
are sun dried and processed to extract the insecticide
pyrethrum.
Pyrethrum is an ancient insecticide.
The insecticidal properties of the flowers were documented in
the early 1800s but it is suspected that the flowers were used to
kill insects well before this time.
The first commercially available products were powders made from
ground flowers and later crude oil extractions became popular.
Today, the refining of crude pyrethrum extract to remove plant
materials, such as waxes, is a highly complex process resulting in
a very high grade product.
Pyrethrum degrades rapidly in the environment
Pyrethrum has been used effectively to control insects for
decades and is non-persistent, decomposing rapidly in the
environment. This rapid degradation of pyrethrum has resulted in
very few known cases of insect resistance, making it an excellent
choice for the control of agricultural pests.
Its rapid degeneration after application means it has a
withholding period of only one day - spray today, wait a day and
then safely harvest and eat treated food plants on the following
day.
Pyrethrum is the active ingredient in Defender™ Pyrethrum Insect
Spray.