Once more let me repeat the fact that by far the most effective campaign against the insects and other pests that infest rose plants is to be found, not in sprayings and dustings, but rather in maintaining to the best of our ability a condition of health in the plant itself. Prevention here, as always, is better than cure. Nor can it be too strongly emphasized that the daily use of a powerful but finely divided spray from the hose will make life on the rose plant miserable for practically all of the parasites.
The following are the chief enemies that we may encounter in the rose garden. They are briefly described so as to be recognizable when found, and for the annihilation or keeping in check of each is given one of the many remedies. Practically every rosarian develops, after a time, his own pet formulæ for these poisons, so that rose books will be found to contain a wonderfully varied assortment of weapons—so numerous in fact that one would think the army of rose pests could never live to continue their depredations another season.
Aphis or Green Fly
A small, pale green louse, winged or wingless, with a soft, fat, oval body apparently too big for its legs. A single aphis in five generations may become the progenitor of 6,000,000,000.
Tobacco smoke is an excellent weapon, or, if a spray is found more convenient to apply, a solution of 4 oz. of tobacco stems boiled for 10 min. in 1 gal. of soft water, will do. The same weight of quassia chips may be substituted for the tobacco. If the tobacco is used, the cheapest that can be bought is the best for the purpose. Strain the solution and add 4 oz. of soft soap while it is still hot, stirring well to dissolve the soap.
Another remedy—1 qt. of soft soap boiled in 2 qts. of soft water, adding 1 pt. of paraffin before cooling—is well recommended. It should be applied diluted with soft water to ten times its bulk. The paraffin acts as an astringent which, together with the soft soap, cleanses the plant of honey-dew, which is exuded by the aphis to protect its feet against cold and wet.
Mildew
A fungous disease that may appear when the rose plants are in a damp, shady or ill-ventilated location. Although some varieties are more susceptible than others to this disease, the rose garden located out in the open, where the air has unobstructed access, will not be troubled much by mildew. When the disease appears late in the autumn it need not be feared.
Dusting flowers of sulphur upon the foliage, taking care to reach the under side of leaves as well as the upper, and upon the ground about the plants, is a well established remedy. It will be found convenient to shake the powder from a baking-powder can, the end of which is punched with holes, if a regular powder gun is not at hand. Use the sulphur in the early morning, when the dew will help to hold it on the leaves, or else spray the plants with water beforehand.
Rose Thrip