158 



THE AGRICULTURAL NEWS 



Mav 19, 1917. 



PLANT DISEASES. 



The conclusion reached is that the disease is not of 

 a virulent nature, progress being slow, and so far as could be 

 seen, confined to canes whose normal growth has been inter- 

 fered with, apparently, in the outbreak under consideration, 

 by the wrenching action of strong winds or the presence in 

 the stool of the root fungus Marasiuiiis sacchaiH. 



CEPHALOSPORIUM DISEASE OF 



SUGAR-CANE. 



The Report of the Barbados Department of Agriculture, 

 for 1915-16, issued as a supplement to the Official Gazette of 

 April 16, 1917, contains an account by Mr. J. Sydney Dash, 

 Assistant Superintendent, of the epidemic of a sugar-cane 

 Btem disease which occurred in that island in 1915. Some 

 notes on the subject appeared in the issue of this Journal 

 dated January 1, 191(>. The outbreak had a distinctly 

 curious history. In the absence of any obvious irregularitj- 

 in the weather conditions, and although there is good 

 reason to believe that it is not a recent introduction, the 

 ■disease assumed epidemic form with apparent .suddenness 

 and with a wide distribution. 



Appearances suggested the beginning of a severe attack, 

 (but its progress was arrested as quickly as it had begun, and 

 the actual damage done was not serious. So far as is known 

 to the reviewer there has been no notable recurrence this 



Jfear. 



The principal addition to our information afforded by 

 Mr. Dash's account lies in his description of inoculation 

 experiments carried out with lultures of the Cephalosporium 

 isolated from the diseased canes. 



•Some fifteen sound, healthy canes were selected for the 

 purpose and the wounds were made with a sterile cork borer: 

 the cylinder of cane was rejilaced in the hole after a drop of 

 the spore material had been put in with a loop needle, and 

 finally a piece of sterile cotton was bandaged over the wound 

 for protection. The inoculations were made on December 28, 

 1915 Un February 8, 1916, the first examination was made; 

 two inoculated canes were examined and a similar number of 

 <ontrols. Near the wound the tissues were generally invaded 

 by the fungus, which was re isolated Further away from the 

 wound the fungus followed the track of the fibrovascular 

 bundles. The infection extended one internode each way 

 from the point of inoculation. In the controls, only 

 the injured cells around the wound were discoloured 

 but no fungus was found. On March 30 another 

 «xamination was made; four of the inoculated canes were 

 removed. Infection had taken place but little progress was 

 made beyond the results of the first examination. On May IS 

 the remaining canes were removed. After a period of four 

 and a half months, only in two instances was the fungus 

 found to have penetrated almost the entire cane, and these 

 two canes had evidently sustained injuries of some sort; one 

 was damaged by borer at the root and the other showed signs 

 of an incipient attack of Colletotrichum near the base. In 

 all the others the fungus had made very slow progress, 

 two internodes on each side of the one which had been 

 inoculated, were the most that had become infected. 

 One control was attacked by weevil borer near the 

 wound and was useless for comparison. The remainder 

 only showed discoloured tissues near the wound but no 

 fungus was present, neither did they show any discoloration 

 of the bundles as noted in the inoculated canes.' 



SUGAR CANE DISEASES IN PORTO RICO. 



The Fifth Report of the Board of Commissioners of 

 Agriculture of Porto Rico, for the year ending June 1916, 

 contains a report by the Pathologist, Mr. John A. Stevenson, 

 on diseases of sugar-cane. 



The report opens with the statement that there has 

 been heavy loss from cane diseases in the season referred to. 

 This has not been due to the introduction of any new 

 and strange diseases, or to any sudden assumption^ of 

 virulence on the piirt of those fungi already occurring on^the 

 island, but rather has been the result of an accumulation of 

 disease due to a favourable combination of climatic and cul- 

 tural conditions. The trouble has occurred in a compara- 

 tively dry region of the island, and for the most part in the 

 fields of small holders. 



The conditions described are such that no one acijuainted 

 with cane growing would be surprised at the result. The 

 high price of sugar has led to a great extension of the acreage 

 planted, for which neither cultivation nor fertilizer wa& 

 adequately available; and this on heavy long-tilled soils. 

 Excessive rainfall in November and December was followed 

 by severe drought in February, March and April. 



The general effect was to be seen in a stunted appearance 

 of the fields, poor colour of leaves, and the presence of blank 

 spots where stools had died out completely. The stalk.s 

 were small, with close joints, and the internodes discoloured 

 or more or less completely covered with deadened irregular 

 areas, sometimes not extending deeply into the tissues, but 

 at other times forming deep cankers. The few living leaves 

 were narrow and jieculiarly mottled. The lower leaf-sheaths 

 were commonly cemented together by the white mycelial 

 growth of one or more of the fungi connected with root 

 disease. The underground portion of the stools was in 

 advanced cases dry-rotted and permeated by the white 

 mycelium of the 'stellate crystal fungus.' 



The picture thus presented is not, in its general aspect, 

 an unfamilar one in these Islands. For want of a wider term, 

 the type of trouble depicted is commonly called root disease, 

 sometimes, perhaps, froghopper blight. With the definite 

 clear-cut effects which may be produced by Marasmius or 

 Tomaspis it has little intrinsic connexion, and it calls for the 

 ministrations of the agricultural instructor rather than those 

 of the pathologist. 



W.N. 



The influence of certain carbohydrates, chieHy sugars, 

 on green plant.s is described in a note in the Experiment 

 Station Record, Vol. XXXVI, No. 2. Corn (maize) was 

 found able to absorb through its roots and to assimilate 

 certain sugars, which resulted in increased growth of the 

 plant. The sugars in the order of their beneficial effect on 

 the plants when grown in the light were glucose and fructose, 

 saccharose and maltose. In the dark, glucose gave the most 

 beneficial results. With Canada field peas (Pistitu ixitirum) 

 growth was found to respond markedly to the presence of 

 sugars, the order of their beneficial iuHuence being saccharose 

 glucose, maltose and lactose. 



