Sept. 3, 1917 A Nursery Blight of Cedars 539 



mixture, with the addition of flour as an adhesive, in part of the experi- 

 ments. The tests were not started until the disease had appeared in the 

 beds. Experiments are planned with soap as an adhesive, to begin 

 earlier in the season. Difficulty is anticipated in entirely controlling the 

 disease in the nursery with any fungicidal treatments, because of the 

 fact that even a single infection on a young plant is commonly fatal, 

 in contrast to diseases of the leafspot type. Furthermore, infection 

 may apparently occur at any time during the entire growing period. 



As inoculations show that various conifers may serve as hosts for 

 Phoma sp., sanitary measures should include removal of all dead plants 

 or plant parts of other species of white or red cedars, as well as those 

 seriously attacked. The promptness with which spores appear in moist 

 weather emphasizes the need for prompt action if sanitation is to be of 

 value. Spacing the plants farther apart, and taking care to avoid 

 wounds in transplanting or cultivating, should also tend to decrease loss 

 from the disease. 



SUMMARY 



(i) A disease of hitherto unknown origin has for years caused great 

 loss to growers of red cedar in nurseries. It is primarily a disease of 

 young plants, trees over 4 years old being seldom attacked under nursery 

 conditions. 



(2) A species of Phoma occurs commonly on the lesions. Its parasit- 

 ism on 2- to 3-year-old plants of six species of Juniperus, three species 

 of Thuja, and one species of Cupressus has been proved by inoculation 

 at wounds. Control plants with similar wounds remained healthy. 

 The fungus has been recovered from inoculated /. virginiana, and 

 successful reinoculations have been made with it. 



(3) The fungus has now been obtained from Kansas, Nebraska, Iowa, 

 Illinois, and Pennsylvania. The first known collection was made in 

 1900. 



(4) Spraying with commercial lime-sulphur solution and Bordeaux 

 mixture has given little indication of their value as a control measure in 

 incomplete tests so far made. 



