528 DISEASES OF CULTIVATED PLANTS 



application of fungicides. My own experiments and those 

 of Selby, prove conclusively that sulphur is of no value 

 whatever. Bluestone, when of sufficient strength, appears 

 from the evidence that we now have, to be of material value, 

 and when mixed with copperas and lime it is the best of all 

 materials yet experimented with. Although in all my 

 experiments with the paste previously described, copperas 

 was one of the ingredients used, I believe that bluestone and 

 lime made into a paste will be found equally effective. Lime 

 is recognised as the most effective remedy known in treating, 

 or rather preventing * club-root,' a well-known and somewhat 

 similar disease of cabbage. 



From the position and character of the disease, it is evident 

 that no remedy will completely overcome it after the orchard 

 is once attacked. The best that can be done will be to keep 

 the galls from forming on the crowns of the trees, where they 

 do the greatest damage. The galls which form deep down 

 on the lateral roots are of little moment compared with those 

 which come at the crown ; hence, if an orchard be examined 

 yearly and all the galls cut from the crowns, and the wounds 

 covered with the bluestone-copperas-lime paste, there is no 

 reason why a badly infected orchard should not live and fruit 

 for many years. It is not reasonable, however, to expect that 

 the trees will do as well and fruit as abundantly as trees with 

 perfect root systems. 



Tourney, J. W., Univ. of Arizona Agric. Expt. Sta.^ 

 Bull. No. 33 (1900). 



Corky scab of potato is due to the ravages of one of the 

 Myxogastres called Sponogospora scabies (Mass.). This pest 

 was first described by Berkeley more than half a century ago, 

 under the name of Tuburcinia scabies. This was afterwards 

 changed to Sorosporium scabies by Fischer de Waldheim. 

 Both these observers considered the fungus as belonging to 

 the Ustilagineae or 'Smuts,' on account of the spores being 

 produced in clusters or spore -balls. Finally Brunchorst 

 carefully studied the disease in Norway, where it is very 

 prevalent, and discovered that the organism was not a fungus, 

 but a member of the Myxogastres or Mycetozoa, and being 

 unaware of the fact that it had been previously described by 

 Berkeley, called it Spongospora solani. Some people profess 

 to trace the name back with certainty to much older authors, 

 on the strength of retrospective synonymy, but Berkeley's 



