The rose-chafer is often a most pernicious pest on roses, grapes, and other plants. The ungainly, long-legged, grayish beetles occur in sandy regions and often swarm into vineyards and destroy the blossoms and foliage. Spray thoroughly with arsenate of lead, 10 lb. in 100 gal. of water. Repeat the application if necessary. (See under Rose in Chap. VIII.)
San José scale.—This pernicious scale is nearly circular in outline and about the size of a small pin head, with a raised center. When abundant, it forms a crust on the branches and causes small red spots on the fruit. It multiplies with marvelous rapidity, there being three or four broods annually in New York, and each mother scale may give birth to several hundred young. The young are born alive, and breeding continues until late autumn when all stages are killed by the cold weather except the tiny half-grown black scales, many of which hibernate safely. Spray thoroughly in the fall after the leaves drop, or early in the spring before growth begins, with lime-sulfur wash, or miscible oil 1 gal. in 10 gal. of water. When badly infested, make two applications, one in the fall and another in the spring. In case of large old trees, 25 per cent crude oil emulsion should be applied just as the buds are swelling.
In nurseries, after the trees are dug, fumigate with hydrocyanic acid gas, using 1 oz. of potassium cyanide for every 100 cu. ft. of space. Continue the fumigation from one-half to three-quarters of an hour. Do not fumigate the trees when they are wet, since the presence of moisture renders them liable to injury.
Tent-caterpillar.—The insect hibernates in the egg stage. The eggs are glued in ring-like brownish masses around the smaller twigs, where they may be easily found and destroyed. The caterpillars appear in early spring, devour the tender leaves, and build unsightly nests on the smaller branches. This pest is usually controlled by the treatment recommended for the codlin-moth. Destroy the nests by burning or by wiping out when small. Often a bad pest on apple trees.
Violet gall-fly.—Violets grown under glass are often greatly injured by a very small maggot, which causes the edges of the leaves to curl, turn yellowish, and die. The adult is a very minute fly resembling a mosquito. Pick off and destroy infested leaves as soon as discovered. Fumigation is not advised for this insect or for red-spider.
White-fly.—The minute white-flies are common on greenhouse plants and often in summer on plants about gardens near greenhouses. The nymphs are small greenish, scale-like insects found on the under side of the leaves; the adults are minute, white, mealy-winged flies. Spray with kerosene emulsion or whale-oil soap; or if infesting cucumbers or tomatoes, fumigate over night with hydrocyanic acid gas, using 1 oz. of potassium cyanide to each 1000 cu. ft. of space. (See page 188.)
White grubs.—The large curved white grubs that are so troublesome in lawns and strawberry fields are the larvae of the common June beetles. They live in the ground, feeding on the roots of grasses and weeds. Dig out grubs from beneath infested plants. Thorough early fall cultivation of land intended for strawberries will destroy many of the pupae. In lawns, remove the sod, destroy the grubs, and make new sward, when the infestation is bad.
Treatment for some of the common plant diseases.
The following advice (mostly adapted from Whetzel and Stewart) covers the most frequent types of fungous disease appearing to the home gardener. Many other kinds, however, will almost certainly attract his attention the first season if he looks closely. The standard remedy is bordeaux mixture; but because this material discolors the foliage the carbonate of copper is sometimes used instead. The treatments here recommended are for New York; but it should not be difficult to apply the dates elsewhere. The gardener must supplement all advice of this character with his own judgment and experience, and take his own risks.
Apple scab.—Usually most evident on the fruit, forming blotches and scabs. Spray with bordeaux, 5-5-50 or 3-3-50; first, just before the blossoms open; second, just as the blossoms fall; third, 10 to 14 days after the blossoms fall. The second spraying seems to be the most important. Always apply before rains, not after.