Manual of Gardening Part 19

The peach and apricot borer is the larva of a clear-wing moth. The larva burrows just under the bark near or beneath the surface of the ground; its presence is indicated by a gummy ma.s.s at the base of the tree. Dig out the borers in June and mound up the trees. At the same time, apply gas-tar or coal-tar to the trunk from the roots to a foot or more above the surface of the ground.

The bronze birch borer is destroying many fine white birch trees in some parts of the country. Its presence is known by the dying of the top of the tree. There yet is no known way of preventing this borer from attacking white birches, and the only practicable and effective method so far found for checking its ravages is promptly to cut and burn the infested trees in autumn, in winter, or before May 1. There is no probability of saving a tree when the top branches are dead, although cutting out the dead parts may stay the trouble temporarily. Cut and burn such trees at once and thus prevent the spread of the insect.

_Bud-moth on apple._--The small brown caterpillars with black heads devour the tender leaves and flowers of the opening apple buds in early spring. Make two applications of either 1 lb. Paris green or 4 lb.

a.r.s.enate of lead in 100 gal. of water; the first when the leaf-tips appear and the second just before the blossoms open. If necessary, spray again after the blossoms fall.

_Cabbage and cauliflower insects._--The green caterpillars that eat cabbage leaves and heads hatch from eggs laid by the common white b.u.t.terfly (Fig. 295). There are several broods every season. If plants are not heading, spray with kerosene emulsion or with Paris green to which the sticker has been added. If heading, apply h.e.l.lebore.

The cabbage aphides, small mealy plant-lice, are especially troublesome during cool, dry seasons when their natural enemies are less active.

Before the plants begin to head, spray with kerosene emulsion diluted with 6 parts of water, or whale-oil soap, 1 lb. in 6 gal. of water.

The white maggots that feed on the roots hatch from eggs laid near the plant at the surface of the ground by a small fly somewhat resembling the common house fly. Hollow out the earth slightly around every plant and freely apply carbolic acid emulsion diluted with 30 parts of water.

Begin the treatment early, a day or two after the plants are up or the next day after they are set out. Repeat the application every 7 to 10 days until the latter part of May. It has also been found to be practicable to protect the plants by the use of tightly fitting cards cut from tarred paper. (See page 187.)

_Canker-worms._--These caterpillars are small measuring-worms or loopers that defoliate apple trees in May and June (Fig. 217). The female moths are wingless, and in late fall or early spring crawl up the trunks of the trees to lay their eggs on the branches. Spray thoroughly once or twice, before the blossoms open, with 1 lb. Paris green or 4 lb.

a.r.s.enate of lead in 100 gal. of water. Repeat the application after the blossoms fall. Prevent the ascent of the wingless females by means of sticky bands or wire-screen traps.

_Case-bearers on apple._--The small caterpillars live in pistol-shaped or cigar-shaped cases, about 1/4 in. long. They appear in spring on the opening buds at the same time as the bud-moth and may be controlled by the same means.

_Codlin-moth._--The codlin-moth lays the eggs that produce the pinkish caterpillar which causes a large proportion of wormy apples and pears.

The eggs are laid by a small moth on the leaves and on the skin of the fruit. Most of the caterpillars enter the apple at the blossom end. When the petals fall, the calyx is open and this is the time to spray. The calyx soon closes and keeps the poison inside ready for the young caterpillar's first meal. After the calyx has closed, it is too late to spray effectively. The caterpillars become full grown in July and August, leave the fruit, crawl down on the trunk, and there most of them spin coc.o.o.ns under the loose bark. In most parts of the country there are two broods annually. Immediately after the blossoms fall, spray with 1 lb. Paris green or 4 lb. a.r.s.enate of lead in 100 gal. of water. Repeat the application 7 to 10 days later. Use burlap bands on trunks, killing all caterpillars under them every ten days from July 1 to August 1, and once later before winter.

_Cucurbit (cuc.u.mber, melon, and squash) insects._--Yellow, black-striped beetles appear in numbers and attack the plants as soon as they are up. Plant early squashes as a trap-crop around the field.

Protect the vines with screens (Fig. 229) until they begin to run, or keep them covered with bordeaux mixture, thus making them distasteful to the beetles.

Squash vines are frequently killed by a white caterpillar that burrows in the stem near the base of the plant. Plant a few early squashes between the rows of the late varieties as a trap-crop. As soon as the early crop is harvested, remove and burn the vines. When the vines are long enough, cover them at the joints with earth in order to develop secondary root systems for the plant in case the main stem is injured.

Dark green plant-lice feed on the under sides of squash leaves, causing them to curl and wither. Spray with kerosene emulsion diluted with 6 parts of water. It is necessary thoroughly to cover the under side of the leaves; the sprayer, therefore, must be fitted with an upturned nozzle. Burn the vines as soon as the crop is harvested and keep down all weeds.

The stink-bug is very troublesome to squashes. The rusty-black adult emerges from hibernation in spring and lays its eggs on the under side of the leaves. The nymphs suck the sap from the leaves and stalks, causing serious injury. Trap the adults under boards in the spring.

Examine the leaves for the smooth shining brownish eggs and destroy them. The young nymphs may be killed with kerosene emulsion.

_Curculio._--The adult curculio of the plum and peach is a small snout-beetle that inserts its eggs under the skin of the fruit and then makes a characteristic crescent-shaped cut beneath it. The grub feeds within the fruit and causes it to drop. When full grown, it enters the ground, changes in late summer to the beetle, which finally goes into hibernation in sheltered places. Spray plums just after blossoms fall with a.r.s.enate of lead, 6 to 8 lb. in 100 gal. of water, and repeat the application in about a week. After the fruit has set, jar the trees daily over a sheet or curculio-catcher and destroy the beetles; this is practically the only procedure for peaches, for they cannot be sprayed.

The quince curculio is somewhat larger than that infesting the plum and differs in its life-history. The grubs leave the fruits in the fall and enter the ground, where they hibernate and transform to adults the next May, June, or July, depending on the season. When the adults appear, jar them from the tree on sheets or curculio-catchers and destroy them. To determine when they appear, jar a few trees daily, beginning the latter part of May in New York.

_Currant-worm._--In the spring the small green, black-spotted larvae feed on the foliage of currants and gooseberries, beginning their work on the lower leaves. A second brood occurs in early summer. When worms first appear, spray with 1 lb. Paris green or 4 lb. a.r.s.enate of lead in 100 gal. of water. Ordinarily the poison should be combined with bordeaux (for leaf-spot).

_Cut-worms._--Probably the remedy for cut-worms most often practiced in gardens, and which cannot fail to be effective when faithfully carried out, is hand-picking with lanterns at night or digging them out from around the base of the infested plants during the day. Bushels of cut-worms have been gathered in this way, and with profit. When from some cause success does not attend the use of the poisoned baits, to be discussed next, hand-picking is the only other method yet recommended that can be relied upon to check cut-worm depredations.

The best methods yet devised for killing cut-worms in any situation are the poisoned baits, using Paris green or a.r.s.enate of lead for the purpose. Poisoned bunches of clover or weeds have been thoroughly tested, even by the wagon-load, over large areas, and nearly all have reported them very effective; lamb's quarters (pigweed), pepper-gra.s.s, and mullein are among the weeds especially attractive to cutworms. On small areas the making of the baits is done by hand, but they have been prepared on a large scale by spraying the plants in the field, cutting them with a scythe or machine, and pitching them from wagons in small bunches wherever desired. Distributed a few feet apart, between rows of garden plants at nightfall, they have attracted and killed enough cut-worms often to save a large proportion of the crop; if the bunches can be covered with a shingle, they will keep fresher much longer. The fresher the baits, and the more thoroughly the baiting is done, the more cut-worms one can destroy. However, it may sometimes happen that a sufficient quant.i.ty of such green succulent plants cannot be obtained early enough in the season in some localities. In this case, and we are not sure but in all cases, the poisoned bran mash can be used to the best advantage. It is easily made and applied at any time, is not expensive, and thus far the results show that it is a very attractive and effective bait. A tablespoonful can be quickly dropped around the base of each cabbage or tomato plant; small amounts may be easily scattered along the rows of onions and turnips, or a little dropped on a hill of corn or cuc.u.mbers.

The best time to apply these poisoned baits is two or three days before any plants have come up or been set out in the garden. If the ground has been properly prepared, the worms will have had but little to eat for several days and they will thus seize the first opportunity to appease their hunger upon the baits, and wholesale destruction will result. The baits should always be applied at this time wherever cut-worms are expected. But it is not too late usually to save most of a crop after the pests have made their presence known by cutting off some of the plants. Act promptly and use the baits freely.

For mechanical means of protecting from cut-worms, see pp. 186-7.

_Elm-leaf beetle._--Generally speaking one thorough and timely spraying is ample to control the elm-leaf beetle (Fig. 235). Use a.r.s.enate of lead, 1 lb. to 25 gal., and make the application to the under side of the leaves the latter part of May or very early in June in New York.

Occasionally, when the beetle is very abundant, due in all probability to no spraying in earlier years, it may be advisable to make a second application, and the same may be true when conditions necessitate the application earlier than when it will be most efficacious. This latter condition is likely to obtain wherever a large number of trees must be treated with inadequate outfit.

[Ill.u.s.tration: Fig. 235. Elm-leaf beetle, adult, somewhat enlarged (after Howard).]

_Oyster-sh.e.l.l scale._--This is an elongate scale or bark-louse, 1/8 in.

in length, resembling an oyster sh.e.l.l in shape and often incrusting the bark of apple twigs. It hibernates as minute white eggs under the old scales. The eggs hatch during the latter part of May or in June, the date depending on the season. After they hatch, the young may be seen as tiny whitish lice crawling about on the bark. When these young appear, spray with kerosene emulsion, diluted with 6 parts of water, or whale-oil or any good soap, 1 lb. in 4 or 5 gal. of water.

_Pear insects._--The psylla is one of the most serious insects affecting the pear tree. It is a minute, yellowish, flat-bodied, sucking insect often found in the axils of the leaves and fruit early in the season. They develop into minute cicada-like jumping-lice. The young psyllas secrete a large quant.i.ty of honey-dew in which a peculiar black fungus grows, giving the bark a characteristic sooty appearance. There may be four broods annually and the trees are often seriously injured.

After the blossoms fall, spray with kerosene emulsion, diluted with 6 parts of water, or whale-oil soap, 1 lb. in 4 or 5 gal. of water. Repeat the application at intervals of 3 to 7 days until the insects are under control.

The pear slug is a small, slimy, dark green larva which skeletonizes the leaves in June, and a second brood appears in August. Spray thoroughly with 1 lb. Paris green, or 4 lb. a.r.s.enate of lead, in 100 gal. of water.

_Potato insects._--The Colorado potato beetle, or potato-bug, emerges from hibernation in the spring and lays ma.s.ses of orange eggs on the under side of the leaves. The larvae are known as "slugs" and "soft-sh.e.l.ls" and cause most of the injury to the vines. Spray with Paris green, 2 lb. in 100 gal. of water, or a.r.s.enite of soda combined with bordeaux mixture. It may sometimes be necessary to use a greater strength of the poison, particularly on the older "slugs."

The small black flea-beetles riddle the leaves with holes and cause the foliage to die. Bordeaux mixture as applied for potato blight protects the plants by making them repellent to the beetles.

_Raspberry, blackberry, and dewberry insects._--The greenish, spiny larvae of the saw-fly feed on the tender leaves in spring. Spray with Paris green or a.r.s.enate of lead, or apply h.e.l.lebore.

The cane-borer is a grub that burrows down through the canes, causing them to die. In laying her eggs, the adult beetle girdles the tip of the cane with a ring of punctures, causing it to wither and droop. In midsummer, cut off and destroy the drooping tips.

_Red spider._--Minute reddish mites on the under sides of leaves in greenhouses and sometimes out of doors in dry weather. Syringe off the plants with clear water two or three times a week, taking care not to drench the beds.

_Rose insects._--The green plant-lice usually work on the buds, and the yellow leaf-hoppers feed on the leaves. Spray, whenever necessary, with kerosene emulsion, diluted with 6 parts of water, or whale-oil or any good soap, 1 lb. in 5 or 6 gal. of water.

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 a.r.s.enate of lead, 10 lb. in 100 gal. of water. Repeat the application if necessary. (See under Rose in Chap. VIII.)

_San Jose 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 pota.s.sium cyanide for every 100 cu. ft. of s.p.a.ce.

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 ma.s.ses 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 gla.s.s 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 cuc.u.mbers or tomatoes, fumigate over night with hydrocyanic acid gas, using 1 oz. of pota.s.sium cyanide to each 1000 cu. ft. of s.p.a.ce. (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 gra.s.ses 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._

_Asparagus rust._--The most common and destructive disease of asparagus, producing reddish or black pustules on the stems and branches. Late in the fall, burn all affected plants. Fertilize liberally and cultivate thoroughly. During the cutting season, permit no plants to mature and cut all wild asparagus plants in vicinity once a week. Rust may be partially controlled by spraying with bordeaux, 5-5-50, containing a sticker of resin-sal-soda soap, but it is a difficult and expensive operation and probably not profitable except on large acreage. Begin spraying after cutting as soon as new shoots are 8 to 10 in. high and repeat once or twice a week until about September 15. Dusting with sulfur has proved effective in California.

_Cabbage and cauliflower diseases._--Black-rot is a bacterial disease; the plants drop their leaves and fail to head. Practice crop rotation; soak seed 15 min. in a solution made by dissolving one corrosive sublimate tablet in a pint of water. Tablets may be bought at drug stores.

Club-root or club-foot is a well-known disease. The parasite lives in the soil. Practice crop rotation. Set only healthy plants. Do not use manure containing cabbage refuse. If necessary to use infested land, apply good stone lime, 2 to 5 tons per acre. Apply at least as early as the autumn before planting; two to four years is better. Lime the seed-bed in same way.