In accordance with an announcement in the March number of the
_Naturalist_, the editor of this department has sent out the seed of two
species of pyrethrum, viz. _P. roseum_ and _P. cinerarioefolium_, to
a large number of correspondents in different parts of North America.
Every mail brings us some inquiries for further particulars and
directions to guide in the cultivation of the plant and preparation of
the powder. We have concluded, therefore, that such information as is
obtainable on these heads will prove of public interest, and we shall
ask Professor Bessey's pardon for trenching somewhat on his domain.
There are very few data at hand concerning the discovery of the
insecticide properties of pyrethrum. The powder has been in use for many
years in Asiatic countries south of the Caucasus mountains. It was sold
at a high price by the inhabitants, who successfully kept its nature a
secret until the beginning of this century, when an Armenian merchant,
Mr. Jumtikoff, learned that the powder was obtained from the dried
and pulverized flower-heads of certain species of pyrethrum growing
abundantly in the mountain region of what is now known as the Russian
province of Transcaucasia. The son of Mr. Jumtikoff began the
manufacture of the article on a large scale in 1828, after which year
the pyrethrum industry steadily grew, until to-day the export of the
dried flower-heads represents an important item in the revenue of those
countries.
Still less seems to be known of the discovery and history of the
Dalmatian species of pyrethrum (_P. cinerarioefolum_), but it is
probable that its history is very similar to that of the Asiatic
species. At the present time the pyrethrum flowers are considered by far
the most valuable product of the soil of Dalmatia.
There is also very little information published regarding either the
mode of growth or the cultivation of pyrethrum plants in their native
home. As to the Caucasian species we have reasons to believe that they
are not cultivated, at least not at the present time, statements to the
contrary notwithstanding.[1]
[Footnote 1: Report Comm. of Patents, 1857, Agriculture, p. 130.]
The well-known Dr. Gustav Radde, director of the Imperial Museum of
Natural History at Tiflis, Transcaucasia, who is the highest living
authority on everything pertaining to the natural history of that
region, wrote us recently as follows: "The only species of its genus
_Pyrethrum roseum_, which gives a good, effective insect powder, is
nowhere cultivated, but grows wild in the basal-alpine zone of our
mountains at an altitude of from 6,000 to 8,000 feet." From this it
appears that this species, at least, is not cultivated in its native
home, and Dr. Radde's statement is corroborated by a communication of
Mr. S. M. Hutton, Vice-Consul General of the U. S. at Moscow, Russia, to
whom we applied for seed of this species. He writes that his agents were
not able to get more than about half a pound of the seed from any one
person. From this statement it may be inferred that the seeds have to be
gathered from the wild and not from the cultivated plants.
As to the Dalmatian plant it is also said to be cultivated in its native
home, but we can get no definite information on this score, owing to the
fact that the inhabitants are very unwilling to give any information
regarding a plant the product of which they wish to monopolize. For
similar reasons we have found great difficulty in obtaining even small
quantities of the seed of _P. cinerarioefolium_ that was not baked or in
other ways tampered with to prevent germination. Indeed, the people
are so jealous of their plant that to send the seed out of the country
becomes a serious matter, in which life is risked. The seed of
_Pyrethrum roseum_ is obtained with less difficulty, at least in small
quantities, and it has even become an article of commerce, several
nurserymen here, as well as in Europe, advertising it in their
catalogues. The species has been successfully grown as a garden plant
for its pale rose or bright pink flower-rays. Mr. Thomas Meehan, of
Germantown, Pa., writes us: "I have had a plant of _Pyrethrum roseum_ in
my herbaceous garden for many years past, and it holds its own without
any care much better than many other things. I should say from this
experience that it was a plant which will very easily accommodate itself
to culture anywhere in the United States." Peter Henderson, of New York,
another well-known and experienced nurseryman, writes: "I have grown the
plant and its varieties for ten years. It is of the easiest cultivation,
either by seeds or divisions. It now ramifies into a great variety of
all shades, from white to deep crimson, double and single, perfectly
hardy here, and I think likely to be nearly everywhere on this
continent." Dr. James C. Neal, of Archer, Fla., has also successfully
grown _P. roseum_ and many varieties thereof, and other correspondents
report similar favorable experience. None of them have found a special
mode of cultivation necessary. In 1856 Mr. C. Willemot made a serious
attempt to introduce and cultivate the plant[1] on a large scale in
France. As his account of the cultivation of pyrethrum is the best
we know of we quote here his experience in full, with but few slight
omissions: "The soil best adapted to its culture should be composed of
pure ground, somewhat silicious and dry. Moisture and the presence of
clay are injurious, the plant being extremely sensitive to an excess of
water, and would in such case immediately perish. A southern exposure is
the most favorable. The best time for putting the seeds in the ground is
from March to April. It can be done even in the month of February if the
weather will permit it. After the soil has been prepared and the seeds
are sown they are covered by a stratum of ground mixed with some
vegetable mould, when the roller is slightly applied to it. Every five
or six days the watering is to be renewed, in order to facilitate the
germination. At the end of about thirty or forty days the young plants
make their appearance, and as soon as they have gained strength enough
they are transplanted at a distance of about six inches from each other.
Three months after this operation they are transplanted again at a
distance of from fourteen to twenty inches, according to their strength.
Each transplantation requires, of course, a new watering, which,
however, should only be moderately applied. The blossoming of the
pyrethrum commences the second year, toward the end of May, and
continues to the end of September." Mr. Willemot also states that the
plant is very little sensitive to cold, and needs no shelter, even
during severe winters.
[Footnote 1: Mr. Willemot calls his plant _Pyrèthre du Caucase (P.
Willemoti._ Duchartre), but it is more than probable that this is only
a synonym of _P. roseum_. We have drawn liberally from Mr. Willemot's
paper on the subject, a translation of which may be found in the Report
of the Commissioner of Patents for the year 1861, Agriculture, pp.
223-331.]
The above quoted directions have reference to the climate of France, and
as the cultivation of the plant in many parts of North America is yet
an experiment, a great deal of independent judgment must be used. The
plants should be treated in the same manner as the ordinary Asters of
the garden or other perennial Compositae.
As to the Dalmatian plant, it is well known that Mr. G. N. Milco, a
native of Dalmatia, has of late years successfully cultivated _Pyrethrum
cinerarioefolium_ near Stockton, Cal., and the powder from the
California grown plants, to which Mr. Milco has given the name of
"Buhach," retains all the insecticide qualities and is far superior to
most of the imported powder, as we know from experience. Mr. Milco
gives the following advice about planting--advice which applies more
particularly to the Pacific coast: "Prepare a small bed of fine, loose,
sandy, loamy soil, slightly mixed with fine manure. Mix the seed with
dry sand and sow carefully on top of the bed. Then with a common rake
disturb the surface of the ground half an inch in depth. Sprinkle the
bed every evening until sprouted; too much water will cause injury.
After it is well sprouted, watering twice a week is sufficient. When
about a month old, weed carefully. They should be transplanted to loamy
soil during the rainy season of winter or spring."
Our own experience with _P. roseum_ as well as _P. cinerarioefolium_
in Washington, D. C., has been so far quite satisfactory. Some that we
planted last year in the fall came up quite well in the spring and will
perhaps bloom the present year. The plants from sound seed which we
planted this spring are also doing finely, and as the soil is a rather
stiff clay and the rains have been many and heavy, we conclude that Mr.
Willemot has overstated the delicacy of the plants.
In regard to manufacturing the powder, the flower heads should be
gathered during fine weather when they are about to open, or at the time
when fertilization takes place, as the essential oil that gives the
insecticide qualities reaches, at this time, its greatest development.
When the blossoming has ceased the stalks may be cut within about four
inches from the ground and utilized, being ground and mixed with the
flowers in the proportion of one-third of their weight. Great care must
be taken not to expose the flowers to moisture, or the rays of the sun,
or still less to artificial heat. They should be dried under cover and
hermetically closed up in sacks or other vessels to prevent untimely
pulverization. The finer the flower-heads are pulverized the more
effectually the powder acts and the more economical in its use. Proper
pulverization in large quantities is best done by those who make a
business of it and have special mill facilities. Lehn & Fink, of New
York, have furnished us with the most satisfactory powder. For his own
use the farmer can pulverize smaller quantities by the simple method of
pounding the flowers in a mortar. It is necessary that the mortar be
closed, and a piece of leather through which the pestle moves, such
as is generally used in pulverizing pharmaceutic substances in a
laboratory, will answer. The quantity to be pulverized should not exceed
one pound at a time, thus avoiding too high a degree of heat, which
would be injurious to the quality of the powder. The pulverization being
deemed sufficient, the substance is sifted through a silk sieve, and
then the remainder, with a new addition of flowers, is put in the mortar
and pulverized again.
The best vessels for keeping the powder are fruit jars with patent
covers or any other perfectly tight glass vessel or tin box.--_American
Naturalist_.
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