What could we do in the absence of this wonderful weed? As a luxury it is possibly dispensable, and so are tea and coffee, but as an insecticide it is a great essential. Till we find something better it is the great cure-all of many a florist's establishment. Where fumigation is not possible or permissible, as in conservatories attached to dwelling houses, it is used as dust or in the liquid form, but "smoking," as the gardener calls it, is the way it is universally applied; most effective and cheapest.
Most florists in or near a large town get their steins from the cigarmaker, and pay for them with a plant occasionally sent to Mrs. Havana Filler. If you have to purchase the stems they cost little. Every florist knows his own way of fumigating. I for one don't believe in placing it on the floor to burn itself out. I prefer it in an iron, or galvanized iron, vessel that can be moved along. If you can't stand the smoke, learn to; go to a New York Florists' Club's "smoker," and after that you will survive not only tobacco smoke but the fumes of sulphur. Tobacco stems get very dry in our sheds and are apt to flare if not moistened. The stems should be shaken out a few hours before you intend to smoke and sprinkled. They will then be moist, without being wet.
How thick or dense tobacco smoke should be is a matter of experience. It is experience that allows us to endure it when it is so thick you can scarcely see your hand before you, and would quickly suffocate the tenderfoot. Lightly and often is the motto always to follow. This has been often preached before, yet how true and wise it is. Don't wait to see three generations of greenfly sucking the life blood out of your plants, but have a day to smoke and remember that day, or rather night, to keep it smoky.
There are a few plants that are easily injured by tobacco smoke, and plants having flowers with thin single petals should not be exposed to fumigation when in flower. Those plants that are hurt by tobacco smoke will be noted in their respective cultural directions.
I never noticed that it was any injury to carnations except that it destroyed their odor and left in its place that of stale tobacco, which will last on the flowers for twenty-four hours. There is a difference of opinion about its effect on roses that are producing buds. Some large growers say they fumigate and see no harm, but the majority of good rose growers keep down the aphis by other methods, and the writer sides with the latter. I have on many occasions seen the petals of our best tea roses, Bride and Bridesmaid, malformed and discolored from no cause but tobacco smoke.
While burning tobacco stems will be the method used by many for years to come, we think that burning the tobacco dust is a great improvement. It may cost a trifle more than the stems, but it is not unpleasant to apply and unless used to excess does no harm to the roses. Eastern growers in the neighborhood of New York we have noticed make small conical heaps of the dust on the floor of the houses, and set fire to the apex of the piles and let it smoulder away till it is burnt out.
A great improvement over this we think is burning the dust in cake dishes and for want of a better name, we will call it the cake dish method. Get a number of these tin dishes, usually they are about ten inches long, six or seven inches wide, with an edge about one and three-quarter inches deep. Cut out the bottom across one end and two sides within three-quarters of an inch of the sides, fold back the bottom that has been cut and that answers as a leg or support to raise one end of the dish off the floor three or four inches. In place of the tin bottom which you have removed cut out some pieces of wire mosquito netting that will just lie in the bottom of the dish, spread a quart of the dust on this netting, and at the lower end drop a few drops of kerosene and put a match to the tobacco dust.
The few drops of kerosene will give it a good start, and one end of this dish being three or four inches higher than the other, there is always a good draught and every particle of dust burns, but not quickly; it smoulders for two hours. If you put the tins on the ground beneath a bench or anywhere but a wooden path you can light the tins and go home.
Now this has taken some time to explain and you may think it fussy, yet it is not in the least, If you will pick up the dishes next morning and keep them in the dry till future use, they will last three or four years. We used four dishes in a house 20x150. The great advantage of this plan over burning stems is that for two or three hours the atmosphere is charged with nicotine, at no time is there a dense, hot smoke which hurts the plants, but the aphis and spider get a long treat of nicotine. If you will adopt this plan you will never go back to the burning stems. You should not depend on your local cigar maker for dust, but get the genuine article from a specialist.
Rose growers who use steam have tin vessels which hold one or two bushels of tobacco stems, which are chopped up as a hay cutter would cut them. Into the bottom of this tin vessel runs a 1/2 -inch steam pipe. You can have as many of them as your house requires. When the steam is turned on a dense vapor fills the house, which of course contains nicotine. This is an effectual way of killing the fly, but is objected to by some as producing a soft growth on the roses, and vaporizing the extracts of tobacco is preferred by many.
Some growers profess to keep down the aphis by strewing the stems on the pipes and paths, or laying them between the plants in bunches. This will keep down the aphis if you start perfectly clean and change the stems every two weeks, but it will not kill the fly if they once have a start.
Although tobacco contains the nicotine which is so useful yet a deadly poison, the stems when rotten are not in the least injurious to the soil. I have seen tons of decayed tobacco stems plowed into the land which produced fine crops.