118 SHADE TREES. 



on the foliage, and is wet by the rains it "sets"' and shuts 

 out the light to some extent and reduces the working effici- 

 ency of the plant. 



5. OTHER DISEASES. 



seedbed "Damping off" is one of the most destruc- 



disease. ^ ve diseases of very young plants, especially 



coniferous trees. It is due to fungi which are semi-sapro- 

 phytic in habit, living in wet, decaying organic matter, 

 especially in manure. These organisms become especially 

 active under the warm, moist conditions which are favorable 

 for the germination of the seeds and for the growth of the 

 young plants. The fungi attack these seedlings at the sur- 

 face of the ground causing them to wilt, fall over and die. 

 The fungi continue to live on the dead plants and spread to 

 the living seedlings. The disease is especially prevalent in 

 seed beds and in nature where the plants are growing in 

 crowded conditions. These diseases are responsible in a 

 great measure for the difficulties in growing coniferous seed- 

 lings and other nursery stock in America, 



Treatment. 



The "damping off'' fungi can be controlled to some extent 

 in various ways. One of the most common practices is that 

 of burning a large quantity of vegetable material on the 

 surface of the bed before planting. Formalin disfectioii of 

 the soil is also used extensively. By this method the beds 

 are thoroughly prepared and then drenched with a formalin 

 solution (1 part commercial formalin to 150 to 200 parts 

 water) using three or four quarts to each square foot of bed 

 surface. The beds should then be covered with burlap for 

 24 hours and after that thoroughly aired for about a week. 

 In some cases it may be necessary to make two or three ap- 

 plications, dependent on the character of the soil. This 



