Sept. 3, 1917 



A Nursery Blight of Cedars 



537 



different sets of inoculations were made, four of which were in outdoor 

 nursery beds in Illinois and Michigan during June and August, and the 

 rest in greenhouses in Illinois and at Washington, D. C, under both 

 summer and winter conditions. In most of the experiments the in- 

 oculations were protected by wrapping with raffia after inoculation 

 (PI. 61, A); one or two of the earlier ones were protected instead by 

 moist cotton and oiled paper. In a few of the greenhouse experiments 

 moist chambers were used. In all tests control plants were cleaned, 

 wounded, and subsequently protected in exactly the same way as those 

 inoculated. The results of the inoculations with Phoma sp. on /. vir- 

 giniana are summarized in Table I. 



Table I. — Results of inoculation experiments with Phoma sp. on ^-year-old transplants 



of funiperus virginiana 



Variable factor. 



Condition. 



Num- 

 ber of 

 inocu- 

 lations. 



Per- 

 centage 



in- 

 fected. 



Num- Per- 

 ber of centage 

 control I in- 

 wounds, fected. 



Source of inocu- 

 lum. 



Method of insert- 

 ing inoculum . 



Location of plants . 



jWith cultures from diseased tissue 

 j plantings: Original. 

 /With culttures from diseased tissue 

 plantings: Reisolation. 



Single spore cultures: Original 



Single spore cultures: Reisolation. .. , 



(In deep slits in bark 

 In slits in outer bark (not penetrat- 

 ing cambium). 

 In punctures 



f Greenhouse 



iNursery beds 



87 

 6 



38 



6 



82 



26 



29 

 94 

 43 



75 



50 



92 



100 



87 



38 



97 

 84 

 70 



51 

 6 



40 



6 



56 



23 



24 



74 

 29 



Total. 



137 



80 



103 



The successful inoculations were commonly found to have made 

 perceptible progress into surrounding healthy tissues within five days 

 after the insertion of inoculum. In all cases where moist chambers were 

 used, and in most of the greenhouse experiments without moist chambers, 

 the spore horns characteristic of Phoma sp. developed on the lesions 

 (PI. 61). Many of these spore horns were examined microscopically 

 and their identity confirmed. In some cases the spore horns appeared 

 within two weeks after the making of the inoculation. Infections 

 resulting from inoculations on laterals extended down the lateral into 

 the main stems, just as natural infections appear to do in the field. 

 The control wounds, some of which were on the same plants as the inocu- 

 lations and some on uninoculated plants, not only showed no signs of 

 infection but promptly healed over. 



An additional control was given the experiments by the inoculation 

 results wdth other fungi. In the earlier experiments with Phoma sp. 

 parallel inoculations were made with two other organisms which occurred 

 in the cultures from diseased tissue. None of these parallel inoculations 



