150 Summary of Agricultural Experiments, [may 



out at Bristol University by Messrs. J. H. Priestley and A. E. Lech- 

 mere. Specimens of swedes attacked by this disease were sent 

 from the neighbourhood of Taunton to the University of Bristol. 

 The first indication of attack was described as being the 

 appearance of a small crack on the side of the root, almost as 

 if made by a hoe ; this crack gradually widened, the interior 

 being filled with slimy, rotting tissue, and in many cases the 

 plant died. By infecting pieces of fresh swede and turnip with 

 slime from a diseased root, the decay was shown to be due to bacterial 

 action and not to an injury alone. Several organisms were isolated, 

 and the one to which the disease is attributed is considered to be 

 probably Bacillus oleraceae (Harrison), the cause of soft black rot of 

 cabbages, but also closely allied to Pseudomonus destructans (Potter), 

 which causes soft white rot in turnips, &c. It is suggested, after con- 

 sideration of its appearance on various culture media, that these two 

 organisms may be different growth forms of the same parasitic species. 



The cultures show that the organism is capable of existence as a 

 saprophyte, and this means that it may continue to exist in the soil, 

 on rotting tissue, long after the crop itself has been removed. This 

 makes the question of the extermination of the disease a difficult 

 one ; one obvious precaution is to lengthen the period as far as pos- 

 sible between successive crops of the turnip and cabbage kind when 

 the disease has once appeared. It seems capable of growing in both 

 an alkaline and an acid medium, so that it does not seem clear that 

 any particular dressing applied to the soil would affect its increase. 

 In this particular case of infection the disease was prevalent at the 

 same time, and under the same conditions, as finger-and-toe, which 

 would indicate insufficient lime in the soil. The practical question of 

 the treatment of the soil would, however, need to be investigated by 

 field experiments. 



Wart Disease of Potatoes (Wart Disease of Potatoes, Harper Adams 

 Agric. Coll., 1910). — These experiments are included among those on 

 which a report appeared in the Journal, April, 191 1, p. 42. The present 

 bulletin contains the results of inquiries as to the method of infection 

 and of the spread of the disease, and details of the experiments carried 

 on at the Harper Adams College in 1909 and 1910 to discover resistant 

 varieties of potatoes, and a means of checking the disease by fungicides. 

 The yields of all the varieties resistant to the disease that have been 

 grown are shown. The fungicide dressings that were tried consisted 

 of quicklime, gas lime, sulphur, salt, soot, copper sulphate, sodium 

 borate, potassium sulphide, black sulphur, ferrous sulphate, strawsonite, 

 and a proprietary Black Scab Compound. None of them was found to 

 be of any value. 



