JUNIPER DISEASES 191 



fungus, the same disease has been found to affect several 

 species of juniper, arbor-vitse and cedar. Wet seasons are 

 conducive to epiphytotics of this disease, but it seems never 

 to affect trees more than three or four years old. 



Symptoms. 



This twig-blight may appear at any time and continue to 

 spread throughout the growing season on nursery stock less 

 than four years old. When severe, entire beds of stock may be 

 destroyed. The general appearance of the trees is not unlike 

 that produced by sun-scorch, except that the trees of a given 

 bed are not affected uniformly but die in spots, which are ir- 

 regular in outline and gradually increase in size. The small 

 lateral branches are affected first and soon are killed. The 

 mycelium then extends its growth into the main stem and 

 spreads more rapidly upward than downward. Other lateral 

 twigs may thus become affected and killed before the main stem 

 is girdled. Recently killed laterals show bleached lesions of a 

 purplish or grayish cast at the base where they branch from the 

 main stem. When the main stem is affected and it is cut length- 

 wise with a knife, the cambium and wood are seen to be discolored. 

 Girdling is sometimes not accomplished and the long sunken 

 cankers heal over, leaving a flattened stem. The terminal is 

 often killed directly by the mycelium spreading upward into it 

 before girdling has taken place. Minute black fruiting-bodies 

 break through the epidermis of the leaves and bark even before 

 any outward discoloration is apparent. In moist weather, 

 prominent hair-like twisted tendrils composed of hundreds of 

 the spores of the fungus are pushed out from these fruiting- 

 bodies.. 



The twig-blight of seedling junipers and other conifers is 

 caused by a fungus of the genus Phoma. Only the one type of 



