For many years we had no pests to contend with except our common enemies, the aphis and red spider. Some years ago the rust was imported and became a great scare. Several other diseases were lectured upon, and the disease and its causes illustrated till we thought the cultivation of the carnation was doomed.
Tobacco smoke destroys the aphis and a light fumigation should be often given. There is no neglect more inexcusable than allowing your carnations to become infested with aphis, and their attacks result in the greatest harm to the plants. They puncture the leaves, disrupt the cellular tissue and weaken the plant. Tobacco smoke, burning tobacco dust and diluted nicotine sprayed on the plants are all used to keep down the aphis. We have not seen red spider for several seasons, although never syringing. More air, more room, and perhaps the sulphur which is put on the heating pipes frequently may have helped to prevent the spider from flourishing. If it does appear in May, syringing is the best cure, but it is difficult to dislodge.
The rust was a few years ago most discouraging. There are few varieties now grown that are troubled with the rust. There have been many mixtures advocated for its cure or prevention, chief of which is the Bordeaux mixture with which we sprayed the plants. Little heed is now given to any cure for the rust, many believing that the cure was as bad as the disease, yet the rust is disappearing, and troubles us little; not because we have killed the disease or its spores, but because we have better understanding of the conditions least favorable to the rust's existence, chief of which are absence of moisture on the leaf, air and light between the plants, more and better ventilation, earlier planting and more vigor of growth.
With the exception of dipping the cuttings before and after being in the sand we leave fungicides alone. We use the ammoniacal mixture for the purpose, but if you prefer the Bordeaux mixture you can obtain it in pulp form and dilute it as you need it. Benj. Hammond, Fishkill-on-Hudson, N. Y., prepares the pulp in convenient sized cans and saves you the trouble of making it. I believe that one pipe on each side of the house painted with sulphur is of great assistance in keeping down both red spider and rust. I saw this demonstrated in the case of a house of Daybreak in my neighborhood. They were in a house formerly used for roses and overhead was a 3-inch flow pipe, which had been about covered with sulphur for the benefit of the roses. While several establishments on every side of this house had their Daybreak black with rust, not a grain of it appeared in this house, and this was for the three years during which the rust was most troublesome. No other preventive than this unconscious one was used.