INSECT AND FUNGOID ENEMIES 185 



should be collected and burned, and Larch-trees badly 

 infected with aphides should be sprayed with paraffin 

 emulsion. 



Fungi. 



Peziza Willkommii {the Larch Canker). — In very few 

 districts is this disease entirely absent. Pure plantations 

 of Larch are usually the worst. The fungus finds en- 

 trance to the tree through wounds of any kind made 

 either by insects, rabbits, hail, or through carelessness 

 when planting. It develops under the bark, which 

 ruptures and exudes a large amount of sap. Year by 

 year the canker enlarges, until sometimes it encircles the 

 tree, causing death. Trees of any age up to forty years 

 are attacked on the stem, while older trees may be 

 attacked in the crown. Sometimes a tree may heal over 

 the wound, but the timber near the canker spot is useless. 



A prominent feature of the disease, and which makes 

 its presence easily detected when there is no large canker, 

 is the growth of the little Peziza cups, which are white 

 outside and orange-red inside. 



The disease is sometimes found on Scots Pine, but it 

 seldom cankers the branches, and is more of a saprophyte 

 than a parasite. To prevent the spread of this disease, 

 Larch should seldom be planted pure, and then only in 

 open and dry situations. The Novar method of combat- 

 ing the disease has already been explained — viz., cutting 

 out the badly diseased stems and underplanting those left. 



Agaricus Melleus, Trametes Pini, and Polyporus Sul- 

 phureus, also attack Larch. 



