This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
Green aphis (Aphis rufomaculata) and the black aphis (Macrosiphum sanboni) are sometimes very troublesome. They may be controlled by spraying with "Black Leaf 40" tobacco extract, one part to 800 parts water with soap added. Fumigation with hydrocyanic acid gas is also widely practised by commercial growers. In moderately tight greenhouses, use one ounce potassium cyanide for each 3,500 cubic feet of space for all-night fumigation. For details, see Fumigation. Red Spider (Tetranychus bimaculatus) becomes injurious if neglected. It may be easily controlled by spraying with water, using much force and little water to avoid drenching the beds. The use of sulfur has also a beneficial effect.
Thrips. (See Carnation).
Leaf-tyer (Phlyctsenia ferrugalis) is frequently very abundant in some parts of the country. It is essentially a greenhouse pest although it can five out-of-doors. The greenish whitish striped caterpillars, 3/4inch in length when full grown, feed on the under side of the leaves which they roll or tie together. The moth is pale brownish with an expanse of about 3/4inch. The leaf-tyer is most destructive during the summer months when the temperature is highest. It can be controlled by spraying with arsenate of lead. It is advisable to begin the work early in the season when the insects are less numerous and the plants are small. Care should be taken to hit the under surface of the leaves.
The tarnished plant-bug (Lygus pratensis) often injures the blossom buds by its feeding punctures. This causes wilting and blind growths. The bugs may be excluded from greenhouses with screens. Out-of-doors no satisfactory means of control has been devised. But it has been noticed that plants growing in partial shade are less subject to injury.
Grasshoppers are sometimes injurious. They may be controlled by the use of arsenate of lead or by hand-picking.
Damp-ing-off in the cutting-benches is not uncommon. See Damping-off, page 961. Rust (Puccinia chrysanthemi) is the only serious fungous disease of the chrysanthemum. It is characterized by the reddish brown pulverulent masses on the foliage consisting of the spores of the fungus. The disease is usually not destructive but may make the foliage unsightly. Any leaves appearing diseased should be removed promptly. In watering care should be taken not to wet the foliage, as moisture on the leaves allows new infections. Leaf-blight (Cylin-drosporium) and leaf-spot (Septoria) occur on mature or languishing foliage and usually do little damage.
The same principles are employed in pot culture as when planted upon the bench, with the exception that the plants are generally allowed to produce more blooms. The most popular type of pot-plant for home growing, or for sale by florists and intended for home use, is a compact, bushy plant, 1 1/2 to 2 feet high, branched at the base, and bearing four to twenty flowers averaging 3 to 4 inches across. They are here called "market plants." "Single-stem plants" are also popular. Great quantities of large flowers (say twenty to one hundred) are rarely grown on a potted plant, except for exhibitions. Such plants are commonly called "specimens," and the three leading forms are the bush, the standard and the pyramid, the first mentioned being the most popular.
Dwarf plants of symmetrical form, with foliage down to the pots, are the most salable, and when thus grown require constant attention as to watering and stopping, allowing each plant plenty of room to keep the lower leaves in a healthy condition. Cuttings taken June 1 and grown in pots, or planted on old carnation benches or in spent hotbeds (light soil preferable), and lifted by August 15, will make very good plants 1 to l 1/2 feet high. The reason for lifting early is to have them well established in their flowering pots before the buds are formed.
Same culture as market plants, except that they are restricted to one stem and flower. Those from 1 to 2 feet in height are more effective and useful than tall ones. For this reason, many prefer plunging the pots out-of-doors where they have the full benefit of the sun and air, making them more dwarf than when grown under glass.
Culture same as for specimen plants, except that the nipping should be discontinued July 1 to give sufficient length to the stems. If large flowers are. desired, restrict the plants to eight or ten growths. Such plants can be accommodated m less space than specimens, when the chief object is symmetry.
For large bush plants, the cuttings should be struck early in February, and grown along in a cool airy house, giving attention to repotting as often as necessary. The final potting into 10- or 12-inch pots generally takes place in June. They are potted moderately firm, and watered sparingly until well rooted. As soon as the plants are 5 or 6 inches high the tips should be pinched out, to induce several growths to start. As the season advances and the plants make rapid growth, pinching must be attended to every day up to the latter part of July, to give as many breaks as possible and keep them in symmetrical form. By the middle of August (if not previously attended to), staking and getting the plants in shape will be a very important detail. If stakes are used, they must be continually tied-out, as the stems soon begin to harden, and this work can be best accomplished by looking them over daily. Light stakes of any material may be used. Many other methods are in use, such as wire hoops and wire framework, to which the growths are securely tied.
5. Standards differ from bush plants in having one stout self-supporting stem, instead of many stems. They require the same culture as bush plants, with the exception that they are not stopped, but allowed to make one continuous growth until 3, 4 or 5 feet high, and are then treated the same as bush plants. They require the same attention as to stopping and tying to secure symmetrical heads.
6. Pyramids are only another form of bush plants, and it is optional with the grower which form he prefers.