502 Scientific Proceedings, Royal Dublin Society. 



IX. — Summary. 



A disease of young Tomato plants is described in which the root system 

 and the lower portion of the stem become involved in a rot leading ulti- 

 mately to the death of the plant. The term " Tomato Foot-Rot" is suggested 

 as appropriate for it. 



A species of Phytophthora was isolated from the diseased tissues and was 

 proved to be the cause of the disease. 



The parasite was grown in pure cultures, and in these the development 

 of sexual organs took place. They are the type first described in Phytoph- 

 thora erythroseptica and P. infestans. The fungus is, therefore, a true 

 Phytophthora, and not being identical with any one of the nine previously 

 described members of this genus, is described as a new species under the 

 name of Phytophthora cryptogea. 



The same type of disease, caused by the same fungus, was found to occur 

 naturally in Petunia; and it is extremely probable that the same fungus 

 causes a similar disease in Aster and Gheiranthus 



Artificial inoculations showed that the fungus was also pathogenic to 

 Potato (Solanum tuberosum), Gilia tricolor, and Fagus sylvatica, but not to 

 Scnccio vulgaris, Helianthus annum, or Nicotiana affinis. 



The disease was found to be contracted from the soil. Oospores of the 

 fungus probably hibernate there ; but this point has not been demonstrated 

 conclusively. 



The disease can be prevented by raising Tomato plants in soil thoroughly 

 sterilised by heat ; and individual plants can be cured in many cases by ampu- 

 tating the diseased portion of the plant and treating the healthy remainder 

 as a " cutting." Methods of controlling the disease are briefly outlined. 



