DISKASKS CAUSED BY WOUND FUNGI. . 47 



body of the mature sporophore is very hard and woody. It is 

 obscurely zoned, pale brown and rust colored. 



The white ash disease is one that can be combated with success 

 provided careful attention is given to protecting wounds. Vigor- 

 ously growing trees appear to be particularly susceptible to the 

 disease, since where one diseased tree occurs those in the immediate 

 vicinity are very likely to become infected shortly after. The cut- 

 ting out of all trees which show signs of sporophore formation is 

 therefore recommended. 



RED HEART-ROT OF BIRCH CAUSED BY FOMES FULVUS. 



A heart-rot of the river birch (Betula nigra L.) has been found 

 repeatedly in Missouri and Arkansas. It is caused by Fomes fulvus 

 Fr., which is apparently the fungus which causes such an extensive 

 destruction of the olive trees in Italy. It has been reported in this 

 country on a number of hosts, but especially on the river birch. 



The sporophores generally grow near a branch stub. They are 

 very woody and hard. The young sporophore appears as a small 

 knob, which gradually increases in size and when mature is almost 

 triangular in the cross section. The upper surface is at first rough 

 or hairy, but later becomes perfectly smooth and almost flinty in 

 texture. A number of very fine irregular fissures form on the upper 

 surface in older sporophores, extending parallel to the edge. The 

 upper surface never becomes deeply fissured and broken, as in Fomes 

 igniarius and F. rimosus. The upper surface when mature is a dull 

 red-brown; the lower surface is very smooth and joins the upper at 

 an angle of about 30 degrees. The pores are extremely minute, 

 hardly visible to the naked eye. The mass of the sporophore is 

 very hard and woody and shows decided evidence of stratification. 

 No detailed investigations have as }^et been made as to the nature 

 of the decay induced by the fungus. Diseased trees show a brown 

 rot of the heart wood extending for some 10 or 12 feet both up and 

 down from the points where the sporophores are growing. The 

 wood has a red-brown appearance and crumbles to pieces when 

 crushed. There are no signs of felt-like sheets such as occur in 

 similar brown-rotted wood when destroyed by the sulphur polyporus 

 (Polyporus sulphur e us) . 



SOFT HEART-ROT OF CATALPA CAUSED BY POLYSTICTUS VERSICOLOR. 



The hardy catalpa (Catalpa speciosa Warder) is affected with but 

 one very serious disease, which has been described at length by von 

 Schrenk (83). In the early stages of the disease the wood near the 

 center of the tree becomes discolored, and this discoloration gradually 



79152 Bui. 14909 4 



