DISEASES AND INSECT PESTS 215 



attack the bark will be split and twisted back so as to 

 expose a gaping wound. The fungus which causes this, 

 Coniothyrium fuckelii, produces yellow spore cases from 

 which spores are cast to carry infection to other parts 

 of the bush or to bushes near at hand. 



Rose growers must beware of this disease, and re- 

 member that it will spread rapidly if preventive measures 

 are not taken early. The shoot which has cankerous 

 growth is, naturally, much weakened, and after a winter's 

 exposure to rain and frost the stem cracks and the well- 

 known symptoms of Canker are emphasised. 



Remedies. — Entrance of the fungus must take place 

 through some wound, crack, or laceration. A good 

 sharp knife or the best and keenest secateurs ought to 

 be used in pruning so as not to damage the shoot in any 

 way. Up to the present the best remedial practice for 

 all cankerous growth has been to remove the corky 

 matter round the centre of attack by means of a sharp 

 knife so as to expose the fresh wood ; the diseased parts 

 are then burned, and the wood receives an immediate 

 coating of creosote or, better still, Stockholm (wood) tar. 



All varieties, forced or hardy, are liable to contract 

 this disease {Coniothyrium). Good, preventive work is 

 to burn all rubbish, including prunings, from the rose 

 border ; remove the surface soil round every bush which 

 was attacked, and sterilise it or replace a fresh compost ; 

 avoid fresh or strong nitrogenous manures, which induce 

 excessive growth that seldom ripens ; prevent plants, as 

 far as possible, from receiving a severe check, and never 

 let insects do serious damage to the tissues. 



