ROSELLINIA 231 



a narrow trench about a foot deep round the trunk, at such a 

 distance as to include the main roots, and if the roots are 

 cut through they should be followed and removed. All the 

 removed soil should be thrown inside the trench. Trees 

 that have been killed should be removed, and special care 

 should be exercised in removing the stumps to get all roots 

 possible, as if these are allowed to remain they will form 

 centres ot infection from which the mycelium will rapidly 

 spread. Weeds growing near infected plants should also be 

 removed and burned. A method that has proved beneficial 

 in France is to expose the base of the trunk as far down as 

 possible, and to powder both trunk and surrounding soil 

 liberally with powdered sulphur. 



Hartig, Unters. Forstbot. Inst. Miinchen, 3, p. 95. 



Viala, Mon. du Pourridie des Vignes et des Arbres fruitiers, 



5 Pi- 

 New Zealand white root rot. This destructive disease is 

 caused by Rosellinia radiciperda (Mass.), which is closely 

 allied to the fungus causing white root-rot in Europe 

 Rosellinia necatrix. Mr. Allan Wright of New Zealand de- 

 scribes its ravages as follows : ' This fungus in the mycelial 

 stage attacks a great variety of tree roots, amongst the most 

 conspicuous of which are the apple, pear, peach, and all 

 other common orchard trees. The white thorn is also very 

 subject to its attacks, as well as a great many Abies, and 

 several of the native trees and plants. It also attacks the 

 cabbage, the potato, docks, sorrel, fern, and in fact is almost 

 omnivorous. Its movements are uncertain ; sometimes a tree 

 here and there dies, sometimes a whole row, and very often 

 acres are swept off.' 



The bark just underground, or the roots, are first attacked, 

 and presently a delicate white mycelium is seen on the sur- 

 face of diseased parts. This mycelium forms white strands 

 which run a few inches underground until another victim 

 is reached. As the disease progresses, numerous minute 

 black sclerotia, which eventually give origin to a conidial 

 form of fruit, are formed in the cortex of diseased portions. 

 Next, the mycelium becomes dark-coloured and gives origin 

 to globose, black bodies, called pycnidia, containing stylo- 

 spores. Finally the ascigerous form of fruit is produced on 

 trunks or stumps that have been dead for some time. 



The same or a closely allied form of root-rot appears as a 



