30 



THE AGRICULTURAL NEWS. 



January 17, 1914. 



FUNGUS NOTES. 



SUMMARY OF INFORMATION RESPECT- 

 ING PLANT DISEASES IN 1913. 



In accordance with past custom, a review of the princi- 

 pal matters of interest dealt with in the fungus notes pub- 

 lished in this journal during the year is given below. 



SUGAE-CANE. 



On pages 142 and 158 details are given of experiments 

 carried out by F. W. South and W. It. Dunlop of this 

 Department to test the degree of parasitism of Colletotri- 

 cliuiii falcaiuiii and Melnnconium sacchari, the two fungi 

 associated with the diseased condition of sugarcane popu- 

 larly known in the West Indies as Eind disease. These 

 articles are preceded by a review on page 126 of the 

 previous work on the .subject. The result of the experiments 

 with respect to CoUetotrichum falcatum was the confirmation 

 of the conclusion of previous workers that the fungus is 

 a wound parasite varying greatly in its degree of virulence, 

 and — apart from serious epidemic — causing harm more especi 

 ally owing to the increase in the glucose ratio produced by 

 its invert action on cane sugar. It was not found in these 

 experiments to be communicated by infected cuttings. No 

 evidence of any ability on the part of Melanconiuiii sacchari 

 to act as a parasite was obtained. 



In connexion with Marasmius disease of sugar-cane, it 

 is interesting to note (see page 94) the occurrence on an 

 imported Californian grass in Montserrat of a disease very 

 similar to the root disease of sugar-cane. Marasmius fructi- 

 fications occurred amongst others on the material. 



CITRUS PLAKTS. 



On page 110 appears a note concerning citrus gall.'; 

 from Dominica. Neither the fungus Sj'/iaeropsis tm/iefaciens 

 nor iJacterium iumefficiens, the organisms described as pro- 

 ducing citrus galls in other countries was found in the 

 material and inoculations carried out by South and Dunlop 

 gave negative results. On page 3GG a summary is given of 

 a paper by H. S. Fawcett in which are described an 

 infectious gummosis of citrus trees in California due to 

 Bdtryfu rii/pariis and Pi/t/iiaci/.''tis citi-ophthora. and a method 

 of treatment of the same by means of Bordeaux paste. An 

 important discovery as to the origin of citrus melanose by 



B. F. Floyd and H. E. Stevens in Florida is noted on 

 page 398. The authors attriliute the spots on leaves, stems 

 and fruits to the effect of the germination of the spores of 

 the fungus P/ionio/isis Ciiri washed down liy rain from 

 overhanging dead twigs. 



IIEVEA. 



The occurrence on Hevea of small rounded woody 

 burrs on the bark, interfering considerably with tapping, is 

 described on page 62. It may be added in this connexion 

 that E. Bateson has recently announced in the Btdletin of 

 the Federated Malay States the discovery that the burrs 

 are due to irritation set up by the coagulated latex in old 

 laticiterous vessels. Two articles (pages 222 and 254) 

 deal with the results of an investigation made by 



C. K. Bancroft into the spotting of plantation Para 

 rubber. Several fungi and a bacillus were found to 

 be connected with ditlerent types of spots. The use of 

 formalin solution in the held and of sulphur in the drying 

 houses is recommended. Notes referring to other diseases 

 on Hevea may be found on page 270 (South America) and 

 286 (Southern Nigeria). 



CACAO. 



Particulars are given on page 3(>2 of observations 

 on the witch broom disease of cacao made by J. B. 

 Fiorer in Dutch Guiana. Rejecting the conclusions of 

 lUtzema Bos as to Exoascus Theolroinae and of van Hall 

 and Drost as to Colletoirichum luxilicunt, Eorer attributes 

 the disease to a fungus whose fructifications are at present 

 unknown, but which is almost certainly a Basidiomy- 

 cete. On page 382 appears a review of an important paper 

 by A. Rant, of Java, on the 'pink disease' of cacao, Hevea 

 and other trees caused by Corlicium salmonicolor . It is 

 shown that the pink incrustation, the silky web which forms 

 on the branches in damp situations, the small pink 

 cushions found in cracks in the bark, and the fungus pre- 

 viously known as Necatvr decrrttis which kills the twigs, are 

 all forms belonging to the Corticium. It is also shown that 

 there is little or no specialization of the fungus on its many 

 different hosts. The author regards fungicides as of little 

 avail, but Petch reports that in Cejlon under certain circum- 

 stances, spraying with Bordeaux mixture is successful in 

 preventing the disease. Diseases of cacao in Southern 

 Nigeria are mentioned on page 286. 



COTTON. 



The important sterile fungus Rhizoctonia, familiar as 

 causing the disease of cotton seedlings known as sore shin, 

 has been carefully investigated by F. G. F. Shaw in India, 

 a summary of whose results are given on page 46. A 

 fungus, apparently exactly similar in all respects, occurs on 

 ground nut, jute and cowpea, and closely similar forms 

 occur on many other plants of most varied affinities. Cross- 

 inoculations show that the form on jute is highly specialized, 

 those on cotton, ground nut and covrpea much less so. 

 The best means of control lies in the rotation of crops. Inocu- 

 lation experiments witli cotton boll rots are briefly mentioned 

 on page 62, and some interesting information as to the cotton 

 diseases in Southern Nigeria appears on page 287. 



This account will be continued in the next issue of the 

 Agricultural News. 



SOIL IMPROVEMENT. 



DYNAMITE FOR RUBBER ESTATES. 



The following article has been taken from Tropical 

 Life (December 1913). In view of the experiments 

 with dynamite in Trinidad and Antigua, the informa- 

 tion is particularly interesting. 



Since we contributed our paper to the New York Con- 

 gress on Farming with Dynamite, we have been pleased to 

 notice what steady progress has been made in familiarizing 

 the planting world with the use of explosives for land cultiva- 

 tion. The latest news on the subject recently came to hand 

 in the shape of the following notes, for which we are indebted 

 to the Mala,// Mail, who tells us that of late much discussion 

 has centred round the topic of the use of explosives in agri- 

 cultural operations, and a demonstration carried out on the 

 Government Experimental Plantations by Mr. Macf^ueen, 

 representing Nobel's Explosive Company, Limited, of Lilasgow, 

 will doubtless tend to quicken interest in the question. 



The most recent application of explosives to agriculture 

 has been in the breaking up of 'hard pan' and other impervi- 

 ous subsoils. Recent experiments in America have demon- 

 strated that 'hard pan' can be blasted with advantage, and, 

 in various parts of the world, many acres of land that hitherto 



