Sept. 3, 1917 A Nursery Blight of Cedars 535 



time. It seems to be a common thing for the parasite to infect and kill 

 laterals, and then to enter the main stems through the bases of these 

 laterals. As the fungus travels longitudinally much faster than trans- 

 versely, it freque-ntly happens on plants older than 2 years that the 

 lesions starting at the bases of killed laterals extend vertically for several 

 centimeters and, before the main stem is girdled, kill other laterals above 

 and below the one originally infected. On cutting into lesions on the 

 older stems both the cambium and the underlying wood are found to be 

 involved by a dark-brown discoloration. On stems old enough to have 

 developed considerable resistance to the transverse extension of infec- 

 tions which have entered from killed laterals the longitudinal lesions 

 develop into definite sunken cankers, and further growth on the unaffected 

 side results in a flattening of the stem. 



Lesions on woody stems are often limited, and partial healing has been 

 observed, indicating ultimate recovery. Swollen growth of the stem 

 above the point of girdling, such as is reported for Phoma abietina Hartig ^ 

 {Fusicoccum abietinum Prill, et Delacy) upon silver fir, and Phoma 

 pithya Sacc.^ upon Douglas fir has not occurred upon any of the species 

 of Juniperus or species of Thuja on which the parasitism of this species 

 of Phoma has been observed, and is not to be expected, in view of the 

 longitudinal extension of the lesion. 



It has been frequently evident in the inoculation work that conduction 

 of water is at least at first not seriously interfered with by the lesions. 

 Terminals often remain apparently healthy for weeks after the stems 

 below them have been girdled. Under greenhouse conditions it some- 

 times happens that the terminals remain healthy until killed as a result 

 of inclusion in the lesion, even though the lesion may have first girdled 

 the stem 10 or 15 cm. below the tip. The upward progress of the lesions 

 is very much more rapid than their downward progress. In some cases, 

 under greenhouse conditions, the fungus has been found exuding spore 

 horns from tissue not yet definitely discolored. 



The distribution of the disease in the nursery beds is very irregular, 

 appearing to spread from definite foci. In broadcast seed beds seedlings 

 are in direct contact with each other, so that this type of spread is easily 

 explained. Two nurseries in western Kansas have raised red cedar 

 with distinctly less trouble from the disease than has been reported from 

 nurseries farther east. This, and the report of one of the Middle West 

 nurserymen that the disease is most serious in wet seasons, indicates the 

 importance of a moist climate as a factor favoring the disease. The 

 sticky character of the spores of the parasite points to water rather than 

 to wind as the most important means of dissemination. The distribu- 

 tion of the disease in parallel beds of /. virginiana and /. scopulorum 



1 Hartig, R. text-book op the diseases of trees. [Trans, by William Soraerville.] p. 138-139. 

 London, 1S94. 



^Tubeuf, Karl von. diseases op plants induced by cryptogamic parasites. [Eng. ed. by W. G. 

 Smith.] p. 466. London, New York, and Bombay, 1S97. 



