July, 1912.] 



Plant Sanitation. 



which causes Pink disease on Hevea is 

 indistinguishable from that on tea, or 

 orange ; but if these three proved to be 

 biologic species infection of tea by the 

 fungus on Hevea would be impossible. 

 Unfortunately, Dr. Rant has proved the 

 contrary ; with one possible exception, 

 his experiments have shown that biologic 

 species do not exist in Corticium sal- 

 monicolor, or, in other words, that the 

 fungus on any of its host plants may 

 transfer itself to any other. To put it 

 briefly. Dr. Rant set out to show, if 

 possible, that the disease was not so bad 

 as it appeared, but he has been forced 

 to conclude that it is all that was 

 claimed for it, and indeed rather worse. 



Corticium salmonicolor was known 

 to occur on affected trees in three forms. 

 The typical form is a thin, continuous, 

 pink sheet which becomes cracked in all 

 directions and changes to a yellowish 

 tint when old. In very damp situations, 

 it often takes another form, running 

 over the surface of the cortex in a thin 

 felt of long silky hyphae, usually white 

 or silvery. The third form consists of 

 minute pink cushions, usually elongated 

 vertically, in small cracks in the bark ; 

 in Ceylon, the first formation of these 

 cracks, before tne pink cushions have 

 appeared, has been styled the '' measles" 

 stage. Dr. Rant has, by suitable culti- 

 vations, provided the scientific proof 

 that these three forms are, as was sup- 

 posed, stages of Corticum salmonicolor ; 

 and moreover he has proved that 

 another fungus, which was originally 

 found on Coffee in Malaya and named 

 Necator decretus by Massee, is really 

 a fourth form of the same Corticium. 

 The latter form has not yetbeen recorded 

 from Ceylon. 



One important new fact demonstrated 

 by Dr. Rant is the existence of the 

 mycelium in the wood of the affected 

 plant. By suitable methods, he was able 

 to develop the fungus in pure culture 

 from the mycelium in the wood and to 

 reproduce the disease by inoculations 

 from the pure culture. It follows from 



that, that merely scraping off diseased 

 bark is insufficient to eradicate the 

 fungus. 



In the matter of treatment there is 

 litle new to be recorded. The old 

 method of cutting off and burning the 

 diseased parts is recommended, with the 

 caution that burying is insufficient. 

 Treatment of already diseased trees with 

 fungicides is deprecated, since they can- 

 not kill the fungus in the wood. Car- 

 bolineum proved ineffective on Cinchona, 

 but its effect on tea appeared to be some- 

 what better. 



It is surprising to find that Dr. Rant 

 makes no reference to the successful 

 experiments in preventing the attack of 

 pink disease on Hevea in South India by 

 the use of Bordeaux mixture. From 

 1906 onwards, specimens of "Pink dis- 

 ease " on Hevea were constantly being 

 sent in to Peradeniya by South Indian 

 planters and visiting agents. The advice 

 was repeatedly given that the trees 

 should be sprayed with Bordeaux mix- 

 ture just before the monsoon ; but it was 

 not until about 1909 that the serious 

 nature of the disease in that country was 

 fully recognised and this treatment 

 adopted. The results have proved most 

 satisfactory ; and, seeing that they have 

 been reported on several occasions in the 

 Planters' Chronicle, some knowledge of 

 them should by this time have reached 

 Java. Fortunately, the disease has not 

 been serious enough in Ceylon to war- 

 rant the adoption of that method of 

 prevention. 



The neglect of foreign literature on 

 the subject is a striking, and unexpected, 

 feature of the report under review. 

 There is no reference to any publication 

 from South India, while Ceylon is repre- 

 sented only by a reference to the Zeits- 

 chrift fur Pflanzenkrankheiten (1908), 

 and second-hand information from the 

 Straits Bulletin. One scarcely expects 

 Java to share the splendid isolation of 

 our botanical stations. 



T. PETCH- 



