272 Angewandte Botanik. 



Second a monographic paper on Phytophthora Phaseoli Thaxter 

 on the lima bean. The disease was first discovered in Connecti- 

 cut in 1889 and has spread slowly ever since until it is now known 

 or has been reported from the following states: Connecticut, 

 Nevv' Jersey, Delaware, Long Island (N. Y.), and Mary- 

 land. It is known in Russia also. The lima bean seems to be 

 the only host the pods being most subject to attack although other 

 parts are also diseased. The fungus is carried from flower to flower 

 by insects. The disease is a serious menace to the cultivation of 

 the lima bean and causes much damage in certain localities where 

 this variety is much grown. Moist weather seems to favor the 

 trouble. The characters of the mycelium and conidiospores are 

 given quite fully. The oospores have not previously been found 

 but the writer has discovered them in the seeds of pods badly 

 affected by the fungus. The characters of the oogonia, oospores, 

 and antheridia are stated as fully as they could be noted. Cultures 

 in the laboratory have been made successfully on living beans and 

 artificial media. Selection of seed, rotation of crops, destruction of 

 rubbish, methods of planting, and spraying are mentioned as pre- 

 ventive measures. A bibliographic list of 21 papers completes 

 this part. 



Part three treats of the late blight of potato caused by Phyto- 

 phthora infestans. In 1904 the author gave a first installment of his 

 work with this fungus. The present part treats of the life history 

 of the fungus. The primary infection has been especially studied. 

 Infection from diseased tuber's producing diseased shoots and the 

 conidia being produced thereon did not seem to prove a common 

 method in nature. The first infection was found on the leaves and 

 not on the stems. The first leaves found infected were in contact 

 with the soil and the indications were very strong that this was 

 the manner of infection. Observations seemed to show that where 

 potatoes have been grown the previous year the blight is apt to 

 Start earlier than where they are planted for the first time on a field. 

 The secondary infections are caused by rain washing spores from 

 diseased parts to healthy ones and also causing the zoospores to 

 germinate. The wind is undoubtedly an active agent in distributing 

 the conidia for short distances. Insects are apparently effective in 

 carrying spores some distance. Pure cultures were grown on various 

 media. Plugs of living plant tissue were very good, while sterilized 

 potato was poor. Poor growth resulted on agar and very poor on 

 earth and manure. This seems to show that the fungus does not live 

 in the soil for any length of time. So far as known the fungus is 

 carried over winter in tubers in the shape of dormant mycelium. 

 The oospores of Phytophthora infestans have never been found. 

 Search has been made carefully in different parts of diseased plants 

 without succes. The theory of mycelial strains has seemed to ac- 

 count for this lack of formation of oospores but the author has, if 

 this be true, failed to obtain cultures of different strains. Twelve 

 füll page half tone plates illustrate this report. 



Perley Spaulding. 



Ausgdgeben: 11. September 1906. 



Verlag von Gustav Fischer in Jena. 

 Druck von Gebrüder üotthelft, Kgl. Hofbuchdrucker in Cassel. 



