A PRELLMINARY INVESTIGATION INTO A DISEASE 

 ATTACKING YOUNG CUPRESSUS PLANTS. 



By Averil Maud Bottomley. B.A. 



{Read, July to, iyi8.) 



{Plaices i8-2T.) 



History. 



Serious attention was first directed towards the disease in 

 question in March, 191 5, when a severe outbreak of a disease in 

 young plants of Ciipressus forulosa and C. arisonica at Belfast, 

 Transvaal, was rei)orted to the Department. Examination of the 

 diseased plants revealed the presence of three fungus organisms 

 — Pestalossia sp., Phoma sp. with typical pycnidia and small 

 globose spores, and a Phoma sp. with unusually shaped pycnidia 

 and rather large fusoid spores. As a result of inoculation and 

 cultural experiments continued during 191 5, the first two 

 organisms were eliminated from the investigation, and the third 

 established as the cause of the trouble. 



A more serious outbreak, identical with the first as regards 

 symptoms and results, but showing the presence of the second 

 Phoma only, and affecting a different species of Cupressus, 

 namely. C. macnocarpa, occurred in Pretoria in March of this 

 year (1918). The increasing demand for species of Cupressus 

 as hedge plants, and the devastation caused by the disease in 

 question, seemed to justify and necessitate a further study of 

 the trouble, a record of which is given in this paper. 



Identification of the Fungus. 



Although the above fungus has been referred to the genus 

 Phoma, doubt is felt as to this being its real identity on account 

 of the unusual shape and formation of the pycnidia. A sugges- 

 tion that it might be z Pliomopsis has been seriously considered, 

 but owing to the fact that it agrees entirely with neither genus. 

 and that its cultural characters are typical of a Pliouia, the ques- 

 tion of its identity is left open for the present until investigations 

 are complete. 



On consulting availa])le literature it appeared that the only 

 described species which the Phoma in question at all resembled 

 was Phoma abietina Hartig* {Pusicoccuni abietinum. Prill and 

 Delacv).t and this had to be dismissed on account of essen- 

 tial differences not only in symptoms but in the organism itself, 

 so that until quite recently the fungus was regarded as a new 

 species. A short while ago. however, the writer's attention was 

 directed towards an article entitled, " A Nursery Blight of 

 Cedars," by Hahn, Hartley, and Pierce,J in which a Phoma is 



* R. Hartig: "'Disease of Trees'' (trans, by William Somerville). 

 ■\ Bulletin de la Socictc Mycologiauc de France, 6 [3], 176. 

 XJoum Auric. Research, 10 [10]. 



