ROSE 



ROSE 



3019 



are laid in the tissue of the leaves by a shining black four-winged 

 fly. 



BRISTLY ROSE SLUG (Cladius pectinicornis). Yellowish or 

 greenish, more or less bristly larvse about ?s inch in length that 

 skeletonize the leaves when young but later eat out holes in the leaf, 

 often leaving only the larger veins. In the North there are three 

 generations annually, the cocoons of the summer brood being 

 placed on the leaves or twigs, those of the winter brood on the 

 ground. The eggs of this species are inserted in the petiole of the 

 leaves by the parent fly which very closely resembles the pre- 

 ceding. 



COILED ROSE SLUG (Emphytua cinctus}. Larvse about */i inch 

 in length that feed on the edge of the leaf with the body coiled 

 beneath it. The larva is metallic green spotted with white above, 

 grayish white beneath; head orange; first segment of the thorax 

 blue and the last two gray. Pupation takes place in the pith of a 

 dead twig. 



Treatment for rose slugs. Arsenate of lead, two pounds in fifty 

 gallons of water or one ounce in 1 J^ gallons is an effective spray, 

 but if applied too freely may leave a whitish deposit on the foliage. 

 Hellebore, one ounce in two or three gallons of water, or used in the 

 dry form diluted with double its weight of powdered plaster or 

 cheap flour, is also effective. Rose slugs may also be killed with 

 the nicotine solution as recommended for the rose aphis. 



ROSE LEAT-HOPPEH (Typhlocyba rosae). A small nearly white 

 leaf-hopper, feeding on the under side of the leaves, extracting the 

 juices and causing the leaves to turn yellowish. The insect spends 

 the winter as eggs which are inserted in the bark. 



Treatment. This leaf-hopper may be controlled by thorough 

 spraying of the under side of the leaves with nicotine solution as 

 recommended for the rose aphis. 



ROSE LEAP-ROLLER (Archips rosaceana). Black-headed olive- 

 green caterpillars, about '4 inch in length when mature, that roll 

 and web together the leaves on which they feed. They become full 

 grown in about a month and transform to dark brown pupse within 

 the rolled leaves. In two or three weeks the light brownish moths 

 emerge and deposit their eggs on the leaves. There are two broods 

 annually on roses grown in the open. 



Treatment. Spray the plants with arsenate of lead, two pounds 

 in fifty gallons of water and make the application early in the 

 season. In greenhouses close watch should be kept for the first 

 appearance of the insect and the caterpillars destroyed before they 

 gain a foothold. 



ROSE CHAFES (Macrodactyhis svbspinosus). Long-legged un- 

 gainly grayish brown beetles that swarm into the rose-garden, and 

 devour the leaves, petals, and opening buds. The grubs from 

 which these beetles develop feed on the roots of grasses in sandy 

 soil only. In New York the beetles emerge from the ground about 

 the middle of June and disappear in about a month or six weeks. 



Trtatment. This is a difficult insect to control because the 

 beetles will avoid feeding on foliage poisoned with an arsenical. 

 They will, however, eat leaves sprayed with arsenate of lead sweet- 

 ened with molasses. This method, however, cannot be relied upon 

 to protect the plants when the beetles are numerous, for much 

 damage will be done before the poison has had time to take effect. 

 In the case of a few choice plants it is safer to protect them with 

 mosquito-netting during the period when the beetles are most 

 abundant. 



ROSE MIDGE (Xeocerata rhodophaya). Small whitish or pinkish 

 maggots about one-fourteenth inch in length that infest opening 

 buds, either killing them or causing the leaves and blossoms to be 

 more or less deformed. The maggots become full grown in five to 

 seven days, leave the buds and complete their transformation in 

 the ground. In the summer the total life cycle is completed in 

 about two weeks. As a rule the maggots are most troublesome 

 during June and July. This insect is more injurious to roses grown 

 under glass than in the open. 



Treatment. This is a difficult pest to eradicate once it has 

 become well established in a greenhouse. Rotation with some other 

 crop, such as violets, may be practised to advantage. Fumigation 

 with hydrocyanic acid gas in March, when the growth of the 

 maggots is slow, will be found of value in killing the flies before egg- 

 laying. Fumigation does not give so good results in the summer. 

 It is a good plan to watch the plants carefully and to pick off 

 and destroy au infested buds. See the florist's statement on this 

 pest, page 3017. 



ROSE SCALE (Aulacaspis ross). Snow-white nearly circular 

 scales, about one-tenth inch in diameter, encrusting the branches. 

 More troublesome when roses are grown in partial shade. 



Treatment. Spray with lime-sulfur solution, one gallon in eight 

 gallons of water, while the plants are dormant. It may also be 

 advisable to cut off the worst infested stems. 



ROSE CURCULIO (Rhynchiies tricolor). A bright red snout-beetle, 

 with black legs and snout, which appears on the rose-bushes early 

 in June, eating holes into the unopened buds and puncturing the 

 flower-stems. Some of the injured buds fail to open, while others 

 have the petals riddled with holes. The grubs feed within the buds 

 and young fruit and in late summer descend to the ground where 

 they spend the winter as pupse. 



Treatment. In the garden continued hand-picking of the beetles 

 will be found effective. In larger plantings, arsenate of lead, two 

 pounds in fifty gallons of water one ounce in one and one-half 

 gallons^ will destroy many of the beetles. As the beetles breed in 

 the fruit of the wild rose, these plants should not be permitted to 

 grow in the vicinity of the rose-garden. 



ROSE SLro-CATERpiLLAB (Euflfa indetermina). Occasionally 

 in the South roses are subject to the attack of a caterpillar of 

 striking appearance, about Ji inch in length, orange in color, and 

 covered with tufts of spines. 



Trtatment. In small plantings the caterpillars may be picked 



off by hand. While doing this work gloves should be worn, as the 

 spines of the caterpillar emit an irritating fluid. In larger plantings 

 the caterpillars can be controlled by spraying with arsenate of 

 lead as recommended for the preceding. 



FULLER'S ROSE BEETLE (Aramigus fuUeri). Small grayish 

 brown snout-beetles about % inch in length which are often very 

 destructive to the foliage of roses grown in the greenhouse. The 

 white, curved grubs, about H inch in length, burrow in the soil 

 and feed upon the roots of the plant. 



Treatment. Persistent hand-picking should be practised to 

 prevent the pest from gaining a foothold in the greenhouse. 



MEALY BUGS. These common greenhouse pests are sometimes 

 injurious to rose plants. They may be controlled by syringing the 

 plants with tobacco extract, or a stiff stream of water may be 

 used to dislodge them. 



THRIPS. Minute yellowish or orange insects about one-thirtieth 

 inch in length which often injure the opening blossom-buds of 

 roses grown under glass. They may be controlled by spraying with 

 tobacco extracts or by the use of a sweetened poison made according 

 to the following formula: Water, twelve quarts; pans green, one 

 tablespoonf ul : sugar, three pounds. 



C. R. CROSBY and M. D. LEONARD. 



Rose diseases. 



POWDERY MILDEW, caused by the fungus Sphxrotheca pannosa, 

 is one of the most common and injurious diseases of roses wherever 

 they are grown. It is usually first noticed as grayish or whitish 

 spots on the young leaves or shoots. Later, as the spots enlarge, 

 they have a white, powdery appearance, a felt-like coating being 

 formed, especially about the thorns. The young leaves, stems, and 

 buds are dwarfed, curled, or variously deformed. Injured leaves 

 soon drop, and growth and flower-production is seriously interfered 

 with. Frequently the young buds themselves are attacked by the 

 fungus, rendering the flowers worthless. 



Treatment. (1) Under glass. Thoroughly dusting with sulfur, 

 or spraying with potassium sulfide, one ounce to three gallons of 

 water, every ten days is often sufficient. Ammoniacal copper car- 

 bonate is also effective. Vaporized sulfur, produced either by boiling 

 sulfur in a pot over an alcohol lamp, or by painting the heating- 

 pipes with equal parts of sulfur, lime, and water, can be success- 

 fully used. No time should be lost in applying one of these treat- 

 ments as soon as the mildew appears. Burned sulfur is likely to 

 injure the plants. As one of the conditions favorable to the spread 

 of mildew is dry, cool air, such as would come into the greenhouse 

 from ventilation, broken glass, or open door, care should be taken 

 to eliminate all drafts. (2) Out-of-doors. Outside, rose mildew can 

 be controlled by dusting with finely ground sulfur. Frequent 

 applications should be made, starting with the first appearance 



BLACK SPOT, caused by the fungus Diplocarpon rosae (more 

 commonly known as Actinonema rosa?), is the most common and 

 injurious disease aside from powdery mildew. Roses grown both 

 out-of-doors and under glass are affected. The disease is most 

 destructive during the summer. The more or less circular spots 

 may attain a diameter of a centimeter or more, are of a black 

 color, and are characterized by an irregularly fringed border. The 

 spots occur on the upper surface of the leaf, and by confluence 

 may involve the entire surface. Frequently the leaves become 

 yellow, both in the invaded and uninvaded tissue. Defoliation 

 soon takes place. Bushy sorts are more susceptible than the climb- 

 ing varieties, 



Treatment. The fungus lives over winter on fallen leaves. 

 Therefore, the source of spring infection will be eliminated by 

 gathering and burning all the leaves either late in the fall or early 

 in the spring before the buds expand. However, this is not sufficient 

 entirely to control the disease. It is recommended that the plants 

 be sprayed as soon as the disease becomes manifest, several appli- 

 cations at intervals of a week or ten days being sometimes neces- 

 sary. Bordeaux mixture is said to be effective but is objectionable 

 in that it coats the foliage. As a spray of ammoniacal copper car- 

 bonate is just as effective and lacks this objectionable feature of 

 bordeaux mixture, it is to be given the preference. 



ROSE RUST, caused by the fungus Phragmidium (several species), 

 has been reported occurring on indoor and out^of-dopr roses. It is 

 abundant on wild roses. The disease manifests itself in early spring 

 as orange powdery patches on leaves, shoots, and buds. Fre- 

 quently the greater portion of the surface of the leaf may be cov- 

 ered. The patches on the wood are often large, and distortion or 

 curving of the part affected may occur. Toward autumn, black 

 pustules are to be found on the under side of the leaves and on the 

 stems, the latter of some varieties being killed to the ground. 



Treatment. All fallen infected leaves and all diseased plants or 

 plant parts should be collected and burned. Spraying with potas- 

 sium sulfide has been recommended, but further experimentation 

 with this fungicide is desirable. 



STEM CAXKER, caused by the fungus Coniothyrium wernsdorfiae 

 (probably the same as C. fuckelii). Cankers are formed on the 

 canes and branches, being characterized by a brown center with a 

 black border, outside of which is a reddish zone. 



Treatment. Diseased canes should be cut and burned. 



CBOW-X-GALL, a bacterial disease caused by Bacterium tume- 

 faciens. The disease occurs on plants grown in the open and under 

 glass and is characterized by galls or tubercles being formed on 

 the stems or roots, or both. 



Treatment. Removal or sterilization of the soil by steam, 

 thorough disinfection of the benches, and so on, is the only remedy 

 to be suggested. Rejection of all stock showing any indication of 

 galls is advisable. 



