Canker 



( 168 ) 



Canna 



prevent the circulation of sap, in consequence of 

 which the parts above the disease wither and die. 

 An examination of cracks caused by the fungus, 

 with a magnifying glass, frequently reveals a 

 number of small crimson dots arranged in groups. 

 These are the spore-bearing cases of the fungus. 

 The latter gradually spreads over other parts of the 

 tree, crippling its energies, and in some cases 

 causing its death. 



Canker in Fruit Trees. Taking the Apple as the 

 fruit which suffers most from canker, careful 

 observation has led to the conclusion that the 

 presence of the disease may be traced to various 

 causes, primary and contributive. Though the 

 easiest explanation to offer is that of weak con- 

 stitution, it is nevertheless true that certain varie- 

 ties of Apples are more liable to canker than other.-, 

 and, except in the most favourable circumstances, 

 these susceptible sorts invariably suffer more or 

 less. Ribston Pippin and Lord Snffield are two 

 varieties very liable to canker, though these and 

 other susceptible Apples are quite free from the 

 disease under certain conditions. Where Apples 

 generally suffer from canker, varieties that are very 

 liable to it should be avoided. Doubtless the chief 

 cause of the disease is a lack of some element in 

 the soil ; certainly some soils are more suitable for 

 Apple culture than others. Trees that are planted 

 in cold, wet, undrained land, holding stagnant 

 moisture, frequently suffer, and the same thing is 

 observed when the medium is shallow and the 

 roots penetrate into an unsuitable subsoil formed of 

 retentive clay or marl. Poverty is also a prime 

 cause of canker. From the want of proper nourish- 

 ment trees get into a weak state of health, and are 

 rendered liable to attack. Instances of this may be 

 seen in old orchards, where the trees are debilitated 

 by years of cropping and the absence of manure. 

 Other conditions being favourable for the spread 

 of the fungus, it is facilitated by abrasions of the 

 bark and by the crossing and rubbing of branches. 

 The splitting of the bark on young shoots through 

 the agency of Woolly Aphis and other insects 

 makes a loophole for the introduction and spread 

 of canker. When poverty and unsuitability of soil 

 are prime causes, steps should be taken to check 

 the evil by feeding the trees and improving the 

 rooting medium. If the mischief lies in the sub- 

 soil, means should be adopted for preventing 

 the roots striking into it. These are preventive 

 measures ; for further particulars of remedies see 

 APPLE ENEMIES. 



Parsnip Canker. Parsnips frequently suffer from 

 a disease which causes soft, decayed patches round 

 the crowns and down the sides of the roots. 

 Except in bad cases, the disease does not penetrate 

 far into the roots, though it spoils their appear- 

 ance. The germs of the fungus remain in the soil 

 after the removal of the crop, and the disease 

 invariably appears the next season if Parsnips 

 again occupy the same ground. The soil should 

 be limed. 



Parsley Canker. Occasionally Parsley growing 

 in poor soil dies off through a canker which affects 

 the roots. It is generally in the winter when the 

 plants fail, and the best remedy for the evil lies in 

 a fertile soil and dusting affected plants with soot 

 and lime. 



Rose Canker. Some Roses, chiefly climbers, and 

 notably the popular favourite Marechal Niel, are 

 liable to canker, which frequently causes the death 

 of the variety mentioned. The symptoms are ugly 



swellings of the bark, at the junction of the Kose 

 with the stock, as in the case of standards, at the 

 ground line with trees worked on dwarf stocks, 

 and in various places on old, strong shoots. A 

 successful Rose grower has found that the best 

 remedy is to make an incision through the bark 

 with a sharp knife, beginning well above the 

 wound, cutting through it, and carrying the in- 

 cision below. This causes the bark to open widely, 

 fresh bark quickly appears, and a channel is thus 

 formed for a healthy How of sap to the upper parts 

 of the tree. 



In addition to the instances quoted the roots 

 and stems of other plants are more or less liable to 

 canker in one of its various forms. 



CANNA. (IXDIAN SHOT.) 



Description. A large genus of tropical herb- 

 aceous perennials (tfnf.ScitamineEe) composed of a 

 number of species and numerous garden hybrids 

 and varieties. For many years the Canna was 



FIG. 1. Fio. 2. 



PROPAGATING CANFAS BY DIVISION. 



bud at 

 crocks ; 



Fi^. 1. A fine Canna for planting out of doors. 

 Fig. 2. A Portion of rootstock potted in (>" pot : 



base of flowered stein : b succession Imd ; 



d soil ; e space for water. 

 B Small division of rootstock : / extension bud ; g bud at 



base of stein ; h latent buds ; / 4" pot. 

 C Small division of rootstock, usually discarded : j bud at 



base of flowered ste.in. 



grown almost entirely as a foliage plant for sub- 

 tropical bedding in the summer, but since the 

 introduction of so many beautiful varieties these 

 plants have become highly popular for the sake of 

 their flowers. Since the advent of so many varie- 

 ties the true species have dropped out of favour, 

 and are not often seen in gardens. This is not to 

 be wondered at, considering that garden varieties 

 possess all the grace and beauty of the species as 

 regards foliage, with the addition of gorgeous and 

 many-coloured flowers. Monsieur Annee, a French 

 amateur, was one of the first to attempt the im- 

 provement of Cannas, but public interest in them 

 was only fully aroused when Monsieur Crozy intro- 

 duced his Gladiolus-flowered varieties. Since then 

 the development has been remarkable, and in the 

 Orchid-flowered section, first obtained by crossing 

 the above varieties with the South American 

 species flaccida, we have the largest flowered and 

 the most brilliantly coloured Cannas. Possessing 



