222 



THE AGRICULTURAL NEWS. 



July 5, 1913. 



FUNGUS NOTES. 



THE SPOTTING OF PLA.NTATION PARA 



RUBBER. 



In a recently issued Bulletin (No. 16) of the Department 

 of Agriculture, Federated Malay States, C. K. Bancroft, the 

 late Mycologist to that Department, describes the results of 

 investigations conducted by him, with a view to ascertaining 

 the exact cause, and the possibility of controlling the spotting 

 of plantation Para rubber. Previous explanations of the causes 

 are noted first in the introduction, where reference is niade 

 to the observations of Fetch in Ceylon, and Brook.s in the 

 Straits Settlements, the latter investigator having isolated 

 from spotted area.s a species of bacteria— an organism which 

 the present author was later able to confirm as being one of 

 the several causes of the discoloration in question. 



APPEAEAKCE OF THE SPOTS. 



Proceeding to describe the appearance of the spots on 

 Malaya rubber, it is noted that the colours observed were 

 bright-red, pink, reddish-yellow, dark-blue, bluish-green and 

 bright-yellow, while black and clear spots have been 

 recorded. The colours are usually more clearly visible 

 if the spotted rubber be held up to the light The spots 

 were found to vary in size from small specks of about 

 1 or 2 mm in diameter to large blotches as much as 

 15 cm. in wirtth. Collected evidence showed that the pro- 

 duction of the spotting appeared to be of an epidemic 

 nature, and in some cases the production was limited to one 

 or two fields on a .single estate. Certain forms of pre- 

 pared rubber (e.g. thick crepe) were found to be more 

 susceptible to spotting than others, while some forms have 

 never shown spotting (e.g. smoked sheet). 



CAU.se of SPOTTINii. 



Owing to its opacity, the discoloured rubber could 

 not be easily examined microscopiially. Portions, how- 

 ever, were removed aseptically and placed in sterile 

 cane juice agar and in nutrient bouillon -i- 10. Some- 

 times a growth of a single organism resulted; in other cases 

 common moulds of the Eurotium and Penicellium type 

 appeared besides. It was found after several trials that to 

 obtain a growth of hyphae from the caoutchouc, frc.?h 

 material had to be used. 



The first fungus isolated, which produced a red discolo- 

 ration, was identified provisionally as Munascus /leterofpoms, 

 Schroter— an organism that has been found on the refuse of 

 candle manufacture in Bavaria. In cane juice this fungus 

 produced a red pigment usually within five days, but it was 

 found that continued cultivation in cane juice resulted in 

 a lo.ss of pigment production. 



To make certain that this fungus could cause red discolo 

 ration in rubber, some biscuits were inoculated with it. In 

 some cases the development of a red colour w-as produced 

 From these experimentally discoloured areas the same fungus 

 was re-isolated. 



The next fungus obtained was Spondi/locladium atrovi- 

 reiis, nv. sp., from yellowish red spots on crijpe rublter. No 

 inoculation experiments were carried out as in the previous 

 instance. Following this, a Mycogone-form was obtained 

 from a pink flush that appeared in two sheets of rubber. 

 The colour of the fungus in culture was deep red. Finally, 



of the fungi obtained in these experiments, was a Diplodia- 

 form (Tki/yidaria tarda), which the author ]r\d previously 

 shown to cause a dying back of the stem of the Para rubber 

 tree. This fungus causes a dark blue s[iotting on crepe 

 rubber. 



Perhaps one of the most important causes of red discol- 

 oration in rubber is the presence of an organism which was 

 regarded as being BaciHus 2'^'odigiosus, a species of bacteria 

 which, as is well known, produces a reddening in bread, 

 meat and other articles of diet. Inoculation experiments 

 with this organism were successful. 



Among other organisms suspected of causing discolora- 

 tion were a species of Sterigmato cystis, a red yeast, other 

 bacteria besides B. prodii/iosi", e.g. Sarcinae, and species of 

 Penicellium and Aspergillus, the latter two being regarded 

 as the cause of clear patches on sheet rubber. 



SOURCES OF INFECTION. 



The Diplodia-form isolated is of very common 

 occurrence on recently dead vegetable matter of all 

 kinds, and it is not difKcult to conceive that this 

 fungus can easily gain entrance to the latex, either be- 

 fore or after coagulation. An important result in con- 

 nexion with the sources of infection is contained in the 

 following quotation: 'Poles of uncured jungle wood have 

 been sometimes emploj'ed in drying hc>uses for hanging 

 rubber, and these have been found to bear superficial growths 

 of fungus mycelia. By paring f'fl' thin strips of the poles, 

 and introducing them into nutrient media, growths of three 

 of the above fungi have been obtained, viz: .Unu'isrus heferos- 

 //orus, Sjiondi/lorl<idium maculaiif and the Diplodia form. . . 

 .... The above observations offer a possible explanation 

 of a phenomenon whose nature was for some time quite 

 obscure, viz: the distribution of the spotting on ctepe rubber 

 in transverse bands recurring at intervals. It was not poss- 

 ible to suggest any explanation of this regular distribution of 

 colour until the fungi had been isolated from the racks 

 on which the crepe was hung. On two occasions Spondi/lo- 

 cladium niaculann and the Diplodia-form were obtained both 

 from the wood of the racks, and from the crepe which was 

 in contact with the wood. Each portion of the crOpe which 

 was in contact with the wood was discoloured bluish or 

 black, and reddish yellow. The occurrence of the spotting 

 at intervals is explained by the alteration in the position of 

 the crC-pe as drying progresses, thus presumably exposing 

 a fresh surface to infection by contact with the wood of 

 the rack.' 



In continuation, it was further established in these 

 researches that infection could occur both in the field by the 

 transmission of spores to the latex, or take place in the 

 drying house. Since most of the kinds of spores described 

 occur in the air in abundance, the prevalence of spots on 

 rubber only from one or two fields on an estate would 

 possibly indicate that infection in such cases was derived 

 from the field rather than in the factory. 



In regard to B. jirodiijiosus, outside infection is 

 indicated, possibly through the water placed in the tapping 

 cuts Spotting due to this bacillus usually takes the form 

 of an epidemic, which may art'ect only one or two weeks' 

 output of rubl>er and then disappear for some time. 



TREAT.MENT. 



The methods of treatment suggested in the bulletin 

 under consideratit.n, will be described in the nest issue 

 of the Anririiliural Nav'S. 



