310 Journal of the Department op Agriculture. 



BOTANY. 



At the beginning oi the month Dr. Pole Evans and Dr. Phillips 

 went to Capetown to a conference of botanists to discuss the proposed 

 " pica" survey of the Union in connection with the investigation of 

 lamziekte ; the botanists composing the council of the Botanical 

 Survey have been asked to assist in this matter. 



In the National Herharimn numerous determinations have been 

 made for the Division of Veterinary Research in connection with its 

 work on stock diseases. The Forest Department has also been assisted 

 with identifications of forest trees, and much information has been 

 accumulated with reference to the yellow woods (Podocarpus spp.). 

 Arrangements have recently been made for the acquisition of the 

 valuable collections of E-hodesian plants made by Mr. Fred Eyles ; 

 this will be of great value both from a scientific and economic aspect. 



In the pathological section there has been considerable corres- 

 pondence with farmers on the subject of bacterial diseases of plants, 

 which have been especially prevalent. Bacterial wilt of potatoes and 

 tomatoes has been sent for identification from various localities in the 

 Transvaal, Natal, and Swaziland. 



A particularly severe case of bacteriosis in cotton {Bacteriuvi 

 vialvaceartiTn) was reported from Wolhuters Kop. A large number 

 of seedlings were attacked, remained stunted for some weeks, and 

 finally died. Our correspondent 'stated that this was not a case of one 

 plant dying here and there, but was a matter of acres. Angular leaf- 

 spot caused by the same organism has also been recorded from 

 Swaziland. 



The bacterial disease of tobacco previously recorded from the 

 Piet Retief District is now spreading rapidly at Marikana in the 

 Rustenburg District, and is probably very widespread. So far as the 

 investigation of this disease has gone, it bears a very strong 

 resemblance to the wild fire in tobacco recorded in the United States. 



A bacterial blight of Sudan grass sent from Kaalfontein and 

 found at Groenkloof and in the experimental plots at the Laboratory 

 is also under investigation. 



In connection with the study of ergot on paspalum germinating 

 sclerotia have been found for the first time in South Africa — an 

 important discovery from a scientific point of view, as it completes 

 the life-cycle of the fungus and establishes its identity as Claviceps 

 Paspali. 



On the recommendation of this Division, a further examination 

 of the poplar plantations in the Bedford district was made by the 

 Forestry' Department, and numerous specimens of bark were collected. 

 An examination of these confirmed the opinion that the death of many 

 of these trees in recent years is due to a fungus parasitic on the living 

 trees. The disease is thought to be identical with Cytospor'a chryso- 

 sperma reported from America as causing a serious disease of poplars, 

 willows, etc. 



What promises to be quite a serious disease of arums (Richardia 

 spp.) has recently been noticed. The trouble is characterized by the 

 presence of disfiguring spots on the leaves, which in severe cases cause 

 the death of the latter. It is caused by the fungus Cercospora 

 ricliardiaecola, and spraying experiments are being conducted with a 

 view to finding a means of controlling the disease. 



