GALLS CAUSED BY FUNGI 123 



In June, 1911, the Board of Agriculture and Fisheries 

 issued a leaflet (No. 245) concerning the crown-galls on 

 Plum, Rose, raspberry, and logan-berry recently sent to 

 Kew, and similar galls in every stage of development on 

 the roots of the Paris Daisy {Chrysanthemum frutescens, L.). 



" The galls are usually formed just under ground on the 

 collar or root, and so escape observation. They commence 

 growth as minute wart-like bodies ; growth is rapid, and 

 the surface of the gall becomes coarsely warted and dark 

 coloured, and varies in size from 2 to 3 inches in 

 diameter to that of a football, or even larger. The galls 

 usually decay at the end of one season's growth, and leave 

 an open wound, which penetrates for some distance into the 

 wood. The following season gall growth commences roimd 

 the edge of the wound formed in the previous season. 

 These galls perish in turn, and the process is repeated each 

 season, resulting in a large, deep wound. When two or 

 three such wounds are present on different sides of the 

 collar, the tree usually breaks off at the wounded part. 



" Two distinct organisms have been found to occur in the 

 tissues of the galls, but a bacterium, Bacillus tumefackns, 

 has been proved, in America, to be the primary cause of the 

 disease." 



For remedial and preventive measures the pamphlet 

 should be consulted. Full particulars concerning the 

 fungus pests mentioned in this chapter may be found in 

 Massee's " Textbook of Plant Diseases " and the various 

 leaflets issued by the Board of Agriculture and Fisheries. 



