Manual of Gardening Part 20

_Carnation rust._--This disease may be recognized by the brown, powdery pustules on the stem and leaves. Plant only the varieties least affected by it. Take cuttings only from healthy plants. Spray (in the field, once a week; in the greenhouse, once in two weeks) with copper sulfate, 1 lb.

to 20 gal. of water. Keep the greenhouse air as dry and cool as is compatible with good growth. Keep the foliage free from moisture. Train the plants so as to secure a free circulation of air among them.

_Chestnut._--The bark disease of chestnut has become very serious in southeastern New York, causing the bark to sink and die and killing the tree. Cutting out the diseased places and treating aseptically may be useful in light cases, but badly infected trees are incurable, in the present state of our knowledge. Inspection of nursery stock and burning of affected trees is the only procedure now to be recommended. The disease is reported in New England and western New York.

_Chrysanthemum leaf-spot._--Spray with bordeaux, 5-5-50, every ten days or often enough to protect new foliage. Ammoniacal copper carbonate may be used, but it is not so effective.

_Cuc.u.mber diseases._--"Wilt" is a disease caused by bacteria that are distributed chiefly by striped cuc.u.mber beetles. Destroy the beetles or drive them away by thorough spraying with bordeaux, 5-5-50. Gather and destroy all wilted leaves and plants. The most that can be expected is that the loss may be slightly reduced.

Downy mildew is a serious fungous disease of the cuc.u.mber known among growers as "the blight." The leaves become mottled with yellow, show dead spots, and then dry up. Spray with bordeaux, 5-5-50. Begin spraying when the plants begin to run, and repeat every 10 to 14 days throughout the season.

_Currant diseases._--Leaf-spots and anthracnose are caused by two or three different fungi. The leaves become spotted, turn yellow, and fall prematurely. They may be controlled by three to five sprayings with bordeaux, 5-5-50, but it is doubtful whether the diseases are sufficiently destructive on the average to warrant so much expense.

_Gooseberry powdery mildew._--The fruit and leaves are covered with a dirty white growth of fungus. In setting a new plantation, choose a site where the land is well underdrained and where there is a good circulation of air. Cut away drooping branches. Keep the ground underneath free from weeds. Spray with pota.s.sium sulfide, 1 oz. to 2 gal.; begin when the buds are breaking and repeat every 7 to 10 days until the fruit is gathered. Powdery mildew is very destructive to the European varieties.

_Grape black-rot._--Remove all "mummies" that cling to the arms at tr.i.m.m.i.n.g time. Plow early, turning under all old mummies and diseased leaves. Rake all refuse under the vine into the last furrow and cover with the grape hoe. This cannot be too thoroughly done. The disease is favored by wet weather and weeds or gra.s.s in the vineyard. Use surface cultivation and keep down all weeds and gra.s.s. Keep the vines well sprouted; if necessary sprout twice. Spray with bordeaux mixture, 5-5-50, until the middle of July, after that with ammoniacal copper carbonate. The number of sprayings will vary with the season. Make the first application when the third leaf shows. Infections take place with each rain, and occur throughout the growing season. The foliage should be protected by a coating of the spray before every rain. The new growth especially should be well sprayed.

_Hollyhock rust._--Fig. 212. Eradicate the wild mallow _(Malva rotundifolia)._ Remove all hollyhock leaves as soon as they show signs of rust. Spray several times with bordeaux mixture, taking care to cover both sides of leaves.

_Lettuce drop or rot._--This is a fungous disease often destructive in greenhouses, discovered by the sudden wilting of the plants. It is completely controlled by steam sterilization of the soil to the depth of two inches or more. If it is not feasible to sterilize the soil, use fresh soil for every crop of lettuce.

_Muskmelon diseases._--"Blight'" is a very troublesome disease. The leaves show angular dead-brown spots, then dry up and die; the fruit often fails to ripen and lacks flavor. It is caused by the same fungus as is the downy mildew of cuc.u.mbers. While bordeaux has proved effective in controlling the downy mildew on cuc.u.mbers, it seems to be of little value in lessening the same disease on melons.

"Wilt" is the same as the wilt of cuc.u.mbers; same treatment is given.

_Peach diseases._--Brown-rot is difficult to control. Plant resistant varieties. Prune the trees so as to let in sunlight and air. Thin the fruit well. As often as possible pick and destroy all rotten fruits. In the fall destroy all remaining fruits. Spray with bordeaux mixture before the buds break, or self-boiled lime-sulfur.

Leaf-curl is a disease in which the leaves become swollen and distorted in spring and drop during June and July (Fig. 213). Elberta is an especially susceptible variety. Easily and completely controlled by spraying the trees once, before the buds swell, with bordeaux, 5-5-50, or with the lime-sulfur mixtures used for San Jose scale.

Black-spot or scab often proves troublesome in wet seasons and particularly in damp or sheltered situations. While this disease attacks the twigs and leaves, it is most conspicuous and injurious on the fruit, where it appears as dark spots or blotches. In severe attacks the fruit cracks. In the treatment of this disease it is of prime importance _to secure a free circulation of air_ about the fruit. Accomplish this by avoiding low sites, by pruning, and by removal of windbreaks. Spray as for leaf-curl and follow with two applications of pota.s.sium sulfide, 1 oz. to 3 gal., the first being made soon after the fruit is set and the second when the fruit is half grown.

Yellows is a so-called "physiological disease." Cause unknown.

Contagious, and serious in some localities. Known by the premature ripening of the fruit, by red streaks and spots in the flesh, and by the peculiar cl.u.s.ters of sickly, yellowish shoots that appear on the limbs here and there (Fig. 215). Dig out and burn diseased trees as soon as discovered.

_Pear diseases._--Fire-blight kills the twigs and branches, on which the leaves suddenly blacken and die but do not fall. It also produces cankers on the trunk and large limbs. Prune out blighted branches as soon as discovered, cutting 6 to 8 in. below the lowest evidences of the disease. Clean out limb and body cankers. Disinfect all large wounds with corrosive sublimate solution, 1 to 1000, and cover with coat of paint. Avoid forcing a rapid, succulent growth. Plant the varieties least affected.

Pear scab is very similar to apple scab. It is very destructive to some varieties, as, for example, Flemish Beauty and Seckel. Spray three times with bordeaux, as for apple scab.

_Plum and cherry diseases._--Black-knot is a fungus, the spores of which are carried from tree to tree by the wind and thus spread the infection.

Cut out and burn all knots as soon as discovered. See that the knots are removed from all plum and cherry trees in the neighborhood.

Leaf-spot is a disease in which the leaves become covered with reddish or brown spots and fall prematurely (Fig. 211); badly affected trees winterkill. Often, the dead spots drop out, leaving clear-cut holes.

Spray with bordeaux, 5-5-50. For cherries, make four applications: first, just before blossoms open; second, when fruit is free from calyx; third, two weeks later; fourth, two weeks after third. In plums it may be controlled by two or three applications of bordeaux, 5-5-50. Make the first one about ten days after the blossoms fall and the others at intervals of about three weeks. This applies to European varieties.

j.a.pan plums should not be sprayed with bordeaux.

_Potato diseases._--There are different kinds of potato blight and rot.

The most important are early blight and late blight--both fungous diseases. Early blight affects only the foliage. Late blight kills the foliage and often rots the tubers. Two serious troubles often mistaken for blight are: (1) Tip burn, the browning of the tips and margins of the leaves due to dry weather; and (2) flea-beetle injury, in which the leaves show numerous small holes and then dry up. The loss from blight and flea-beetles is enormous--often, one-fourth to one-half the crop.

For blight-rot and flea-beetles spray with bordeaux, 5-5-50. Begin when the plants are 6 to 8 in. high and repeat every 10 to 14 days during the season, making 5 to 7 applications in all. Use 40 to 100 gal. per acre at each application. Under conditions exceptionally favorable to blight it will pay to spray as often as once a week.

Scab is caused by a fungus that attacks the surface of the tubers. It is carried over on diseased tubers and in the soil. In general, when land becomes badly infested with scab, it is best to plant it with other crops for several years. (See page 190.)

_Raspberry diseases._--Anthracnose is very destructive to black raspberries, but not often injurious to the red varieties. It is detected by the circular or elliptical gray scab-like spots on the canes. Avoid taking young plants from diseased plantations. Remove all old canes and badly diseased new ones as soon as the fruit is gathered.

Although spraying with bordeaux, 5-5-50, will control the malady, the treatment may not be profitable. If spraying seems advisable, make the first application when the new canes are 6 to 8 in. high and follow with two more at intervals of 10 to 14 days.

Cane-blight or wilt is a destructive disease affecting both red and black varieties. Fruiting canes suddenly wilt and die. It is caused by a fungus which attacks the cane at some point and kills the bark and wood, thereby causing the parts above to die. No successful treatment is known. In making new settings, use only plants from healthy plantations.

Remove the fruiting canes as soon as the fruit is gathered.

Red-rust is often serious on black varieties, but does not affect red ones. It is the same as red rust of blackberry. Dig up and destroy affected plants.

_Rose diseases._--Black leaf-spot is one of the commonest diseases of the rose. It causes the leaves to fall prematurely. Spray with bordeaux, 5-5-50, beginning as soon as the first spots appear on the leaves. Two or three applications at intervals of ten days will very largely control the disease. Ammoniacal copper carbonate may be used on roses grown under gla.s.s. Apply once a week until disease is under control.

For mildew on greenhouse roses, keep the steam pipes painted with a paste made of equal parts lime and sulfur mixed up with water. The mildew is a surface-feeding fungus and is killed by the fumes of the sulfur. Outdoor roses that become infested with the mildew may be dusted with sulfur, or sprayed with a solution of pota.s.sium sulfide, 1 oz. to 3 gal. water. Spray or dust with the sulfur two or three times at intervals of a week or ten days.

_Strawberry leaf-spot._--The most common and serious fungous disease of the strawberry; also called rust and leaf-blight. The leaves show spots which at first are of a deep purple color, but later enlarge and the center becomes gray or nearly white. The fungus pa.s.ses the winter in the old diseased leaves that fall to the ground. In setting new plantations, remove all diseased leaves from the plants before they are taken to the field. Soon after growth begins, spray the newly set plants with bordeaux, 5-5-50. Make three or four additional sprayings during the season. The following spring, spray just before blossoming and again 10 to 14 days later. If the bed is to be fruited a second time, mow the plants and burn over the beds as soon as the fruit is gathered. Plant resistant varieties.

_Tomato leaf-spot._--The distinguis.h.i.+ng character of this disease is that it begins on the lower leaves and works towards the top, killing the foliage as it goes. It is controlled with difficulty because it is carried over winter in the diseased leaves and tops that fall to the ground. When setting out plants, pinch off all the lower leaves that touch the ground; also any leaves that show suspicious-looking dead-spots. The trouble often starts in the seed-bed. Spray plants very thoroughly with bordeaux, 5-5-50, beginning as soon as the plants are set out. Stake and tie up for greater convenience in spraying. Spray under side of the leaves. Spray every week or ten days.

CHAPTER VII

THE GROWING OF THE ORNAMENTAL PLANTS--THE CLa.s.sES OF PLANTS, AND LISTS

In choosing the kinds of plants for the main grounds the gardener should carefully distinguish two categories,--those plants to compose the structural ma.s.ses and design of the place, and those that are to be used for mere ornament. The chief merits to be sought in the former are good foliage, pleasing form and habit, shades of green, and color of winter twigs. The merits of the latter lie chiefly in flowers or colored foliage.

Each of these categories should be again divided. Of plants for the main design, there might be discussion of trees for a windbreak, of trees for shade; of shrubs for screens or heavy plantings, for the lighter side plantings, and for incidental ma.s.ses about the buildings or on the lawn; and perhaps also of vines for porches and arbors, of evergreens, of hedges, and of the heavier herbaceous ma.s.ses.

Plants used for mere embellishment or ornamentation may be ranged again into categories for permanent herbaceous borders, for display beds, ribbon edgings, annuals for temporary effects, foliage beds, plants for adding color and emphasis to the shrubbery ma.s.ses, plants desired to be grown as single specimens or as curiosities, and plants for porch-boxes and window-gardens.

Having now briefly suggested the uses of the plants, we shall proceed to discuss them in reference to the making of home grounds. This chapter contains a brief consideration of:

_Planting for immediate effect,

The use of "foliage" trees and shrubs,

Windbreaks and screens,

The making of hedges,

The borders,

The flower-beds,

Aquatic and bog plants,

Rockeries and alpine plants;_

and then it runs into nine sub-chapters, as follows:--