DISEASES OF SHADE AXD FOREST TREES. 109 



surface and produces its sporophores or fruiting bodies. (Fig. 

 4<>. ) These fruiting bodies usually occur at the original 

 wound and are rather conspicuous but variable in shape, size 

 and color. They may be described as hoof- Fru i t i ng 

 shaped, almost as thick as broad, and some- bo* 1 * 8 - 

 times measuring as much as twelve inches in diameter. The 

 upper surface is smooth when young, becoming concentri- 

 cally marked as it grows older. The outer part is hard, 

 brown, gradually becoming black and cracked with age. The 

 pores within which the spores are produced are formed in 

 layers on the underside. The under surface is gray or red- 

 browii in color, varying with the season. The disease works 

 rather slowly, gradually weakening the tree until it is broken 

 by storms. It is one of the most widely distributed of tree 

 diseases and causes enormous losses which, from their wide 

 geographical distribution and wide range of host plants, are 

 extremely difficult to estimate. See also Polyporus sp., p. 111. 



Treatment. 



The most satisfactory treatment for shade and ornamental 

 trees is preventive. When trees become infected the dis- 

 eased parts should be removed and the wounds properly 

 cared for as recommended on page 44. 



RED HEART ROT. 



This rot is caused by the parasitic fungus (Polyporus sul- 

 pliureus (Bull.) Fr.). It attacks the oaks, chestnut, maples, 

 walnuts, locusts, alder, ash, poplar, willows, apple, etc., and 

 is widely distributed throughout ^orth Trees 

 America and Europe. It gains entrance attacked. 

 through wounds and causes the heart wood to rot and be- 

 come reddish brown or black, the color varying somewhat 

 with the host plant. After a period of growth within the 

 wood, it comes to the surface producing a number of large 



