ROOT- GALLS 



ROSA 



2981 



3429. A crown-gall. 



louse (Phylloxera vastatrix) may be readily recognized 

 from other root-galls by the presence of the insects. 

 The young insects, by puncturing the epidermis of the 

 roots" and sucking the sap, cause the galls to develop. 

 The insect is found on the diseased roots in all stages 

 of development during the 

 summer. 



The most effective method of 

 holding the insect in check ap- 

 pears to be in the use of resis- 

 tant roots, i. e., the grafting of 

 the more tender varieties on 

 roots of those that are stronger 

 and better able to resist the 

 attack of the insect. Bisulfide 

 of carbon in some instances 

 has proved effective in killing 

 the lice. 



The crown-gall appears to 

 be the most harmful of root 

 diseases affecting cultivated 

 plants in this country. These 

 galls have been reported upon 

 the roots of the peach, apricot, 

 almond, prune, plum, apple, pear, walnut, grape, rasp- 

 berry, blackberry, cherry, poplar, and chestnut, and 

 without doubt further investigation will find them on 

 other plants as well. The crown-gall disease is now 

 known to be due to a distinct species of pathogenic 

 bacteria (Bacterium lutnefacien-s). It appears to be 

 the same organism in all the host-plants affected 

 by this disease. Seedlings from one to six months 

 old appear to be most susceptible to this disease; 

 hence it is particularly serious in the case of nursery 

 stock. When the galls appear on young trees, they 

 almost always occur on the side of the main root 

 a few inches below the surface of the soil, or in the 

 region of the crown. With more mature trees they are 

 likely to occur at greater depth on lateral roots. At 

 fir*t the gall has a uniform outer appearance, but later 

 it becomes warty from unequal growth. The tissue of 

 the developing gall is soft and succulent, with nodules 

 of woody tissue scattered through it. The galls vary 

 much in size and may reach a diameter of 10 inches. 

 But little is known as to remedies for crown-gall. As 

 the disease is primarily a nursery disease, the most 

 effective remedy is in securing stock for planting from 

 a non-infested nursery. This disease is often destruc- 

 tive to the roots of roses and asters in the greenhouse 

 benches. Here the destruction of all diseased plants 

 followed by steam sterilization of the soil is the only 

 remedy. j. w. TOUMEY. 



H. H. WHETZEL.| 



ROQUETTE, or ROCKET-SALAD (Eruca saftra, 

 Mill.), a low-growing hardy annual from southern 

 Europe, whose leaves resemble those of radish and 

 turnip, is much used by the French as a spring and 

 autumn salad and pot-herb. The flavor of the young, 

 tender leaves, which are the parts used, bears a strong 

 resemblance to that of horse-radish. In America it is 

 but little grown because there are milder-flavored plants 

 that serve the same purpose. See Eruca. 



The first sowing may be made in early spring, the 

 seed being dropped thinly in shallow drills a foot apart, 

 with successional plantings each second or third week 

 through the season. The soil must be rich and well 

 supplied with moisture, else the leaves will probably be 

 tough and acrid. Inter-culture is the same as for spin- 

 ach, lettuce, and similar crops. Frequent watering and 

 tillage in hot dry weather to insure rapid vigorous 

 growth should result in succulent mild-flavored leaves. 

 In summer the plants run rapidly to seed; in spring 

 and autumn they will produce abundantly after being 

 cut. The pale citron-yellow flowers emit a perfume 

 resembling that of orange blossoms. jtf , Q KAIXS. 



RORIPA (etymology unexplained) ; originally spelled 

 Rorippa, but later emended by its author. Cruciferse. 

 Here are included the plants long known as Nasturtium 

 (but not the garden flowers of that name, which belong 

 in Tropaeolum), and by some later botanists as Radic- 

 ula under which name they are described at page 2895. 

 By a ruling of the International Botanical Congress at 

 Brussels, however, the name Radicula is not permissible 

 as it is based on a morphological character; therefore, 

 the plants are transferred (at least temporarily) to 

 Roripa. Under Roripa, the species become R. Nas- 

 turtium, Rusby (Sisymbrium Naslurtium-aquaticum, 

 Linn. Radicula Nasturtium-aqudticum, Brit. & Rend.), 

 the water-cress; R. Armoracia, Hitchc. (Radicula 

 Armordcia, Rob.), the horse-radish; R. indica, Bailey 

 (Sisymbriumindicum, Linn. Nasturtiumindicum, DC.), 

 the tropical cress. L. jj. B. 



ROSA (ancient Latin name). Rosacex. ROSE. 

 Ornamental shrubs chiefly grown for handsome flowers, 

 also for ornamental fruits and attractive foliage. 



Deciduous or sometimes evergreen, upright, less 

 often climbing or creeping shrubs with usually prickly 

 sts.: Ivs. alternate, odd-pinnate, rarely simple, stipu- 

 late (Figs. 3430, 3431): fls. solitary or corymbose at 

 the end of usually short branchlets; petals and sepals 5, 

 rarely 4 ; stamens numerous ; pistils numerous, rarely few, 

 inclosed in an urn-shaped receptacle, which becomes 

 fleshy and berry-like at maturity, containing several or 

 many bony achenes, usually erroneously called seeds; 

 the fr. itself is called a "hip." (Figs. 3432, 3433.) Rosa 

 is a widespread genus, easily distinguished by well- 

 marked characters from allied genera, but in the limits 

 of the genus itself the characters are exceedingly varia- 

 ble and it is very difficult to group into sections and 

 species the innumerable forms which often pass gradu- 



3430. A five-foliolate rose leaf. 



ually into each other. In no other genus, perhaps, are 

 the opinions of botanists so much at variance in regard 

 to the number of species. While some, as Bentham 

 and Hooker, estimate the number at about 30, the 

 French botanist Gandoger actually describes from 

 Eu. and W. Asia alone 4,266 species. The larger num- 

 ber of botanists recognize over 100 species. The roses 



