318 



TEI AGKICriTCKAL XEW5 



October 5, 1918: 



PLANT DISEASES. 



MOULDS OCCURRING ON COPRA AND 

 COCO-NUT MEAT. 



In course of investigations uadertaken by the Bureau 

 of Science, Philippine Islands, in the study of copra and 

 otttr coco-nut products, involving experiments in connexion 

 "with the deterioration ot copra and coco-nut oil both in stor- 

 Agr and in transportation, due to the action of certiiin fungi, 

 the following description of the moulds found to be respon- 

 sible for such deterioration under the conditions obtaining 

 in the Philippines, is abstracted from the results published in 

 tte Phi lip fine Joiiriiai of Scieiia for March 1917. 



We have tound four moulds constantly occurring upon 

 mouldy copra and coco-nut meat The spore masses of these 

 lour moulds differ greatly in colour, and hence the moulds 

 are very readily distinguished even without the use of 

 a microscope. In the order of the moisture necessary for 

 their growth these moulds are Rlii^opus sp. (white mould), 

 a. mould occurring only upon fresh meat, and there forming 

 loose masses of white mycelium with many black spor- 

 argia; Aspergillus niger, van Teigh. (black mould), 

 a mould occurring on copra with a relatively high moisture 

 ccntent, and producing black spore bodies which give the 

 mould a black colour: Aspergillus flavus. Link, (brown or 

 yellow mould), a mould occurring most commonly on mouldy 

 ccpra — the sf)ore masses are first greenish-yellow, later turn- 

 ing brown; Penidllium glaucutn. Link, (green mould), a mould 

 producing green spore masses and common on copra, especially 

 that containing a low percentage of moisture. 



i:nizopi> sf. (white mould) occurs only upon fresh 

 cccc-nut meat, and then only when the surrounding air is in a 

 practically saturated condition. When moisture conditions are 

 favourable, the growth of this mould is very lu.xuriant. It 

 spreads by means of stolons, and in from thirty-six to forty- 

 eight hours the mycelium frequently entirely covers a piece of 

 coconut meat 10 centimetres in diameter with a tangled mass 

 of aerial mycelium, which may attain a height of from "^ to ."i 

 centimetres, and which is specked with small black sporangia. 

 The aerial mycelium collapses upon the .slightest drying. 

 Tce spores germinate in about .six hours in a hanging 

 drop of coconut decoction. Although this mould grows 

 rapidly and destroys a high percentage of the oil in the meat, 

 it is probably the least imjiortant of the four moulds con- 

 sidered in this paper. It grows only upon fresh meat, and 

 hc-cce its growth is checked, and the plant killed almost as 

 scon as drying commences. Rhi-Aipus z^n rarely make any 

 ccnsideiable gr^^wtji. since the meat is usually treated or 

 placed on the grate, and heat applied within the period 

 necessary for the germinati'in of the spore. 



Ai*PEP.<iILHJ> NKJEP., V.AN TEl'ill. (ULA(;K MOULo) 



plays a more important part than doe.s Khi'.opus sp , 

 but a far less important one than does Aspergillus 

 rfi<ivu! (brown mould). It is the black mould often seen 

 on badly moulded copra. Its moisture reijuiremehts are 

 lower than those of white mould, but slightly higher 

 than those of brown mould, and although it often grows 

 with the latter, it appears only upon copra that contains 

 at least 12 per cent, of water, and it makes its most 

 luxuriant growth u[X'n copra that contains l"^ to 20 per 

 cect. of water. Properly dried copra should not have 

 such a high moL^ture content as is required for the 

 growth of this mould. However, as copra is usually prepared 

 in the Phiiippines. it often contains enough water for 

 this mould to appear, and tc make a cocsiderable growth, 



atd ui.der such cccditicts it ui.dcubtedly causes an appreci- 

 able loss in oil. Our esperjments indicate that this loss may 

 sometimes be a.'- nr.uch ■ts 40 per cent, of the total oil. 



In hanging dn ps the spores germinate in about six 

 hours, and the subsequent growth is' rapid. In forty-eight 

 hours the mycelium tn m a sicgle spore may grow out and 

 extend over an area from 3 to 4 centimetres in diameter. On 

 a nutrient agar medium, such as coco nut. prune, or string 

 bean, the colonies are circular in outline, and the substratum 

 is yellow. This colour is also often seen when the mould. 

 grows upon coco-nut or copra, and it appears to be character- 

 istic of the species. 



a.-pei:gillis fl.wus, link, (bkows mouli.) is the 

 mould that plays the most important part in the destruction 

 of the oil in copra. It is the brown mould that is. 

 usually seen on badly moulded copra. In many cases 

 it is mixed with the black Aspergillus, discussed above,, 

 and often with the green Penicillium which is con- 

 sidered later. It occurs upon copra with a moisture 

 content of from 7 to 8 per cent. — a water con- 

 tent lower than the average for Philippine copra — and 

 because of its ability to grow on copra with so low 

 a moisture content it destroys a very high percentage of the 

 copra of the Islands. The oil destroyed may be almost 

 40 per cent, of the total oil contained in the copra- 

 The oil expressed from copra upon which this mould has been 

 growing also contains a high percentage of free fatty acid. 



In bunging drops the .spores germinate in from four to 

 five hours. In nutrient agar media the mycelium becomes 

 visible in from twelve to fifteen hours, and mature spores 

 are produced in about forty-eight hours. The growth from 

 a single spore is slow as compared with one of white mould 

 or black mould, but the early production of spores leads 

 to a rapid multiplication of colonies, and so the mould in a 

 comparatively ^lort time, will completely cover the surface 

 of the meat of half a coco nut. 



PEMciLLiUM CL.MCUM, I.I.N K. (.;i;KE.\ .MoiLi>) is often 

 seen upon copra. It grows well on copra containing 

 a very low percentage of water. Analyses show that 

 this mould destroys hardly any of the oil in the copra, 

 and the production of free acid is low: therefore a good 

 grade of oil can be made from copra upon which this 

 mould has grown. Its growth appears to be almost 

 entirely superficial. It can be readily removed by brush- 

 ing, leaving a firm white copra. A growth of Penicillium 

 alone may be said almost to serve as an indicator of good 

 copra, because it grows at a moisture content between .5 and 

 7 per cent., causes practically no loss in the oil content, and 

 produces very little free acid. However, green mould grow- 

 ing with one or both of the species of Aspergillus loses its 

 significance as an indicator of good copra, as it will grow at 

 any degree of moisture higher than .') or 6 per cent., and 

 the Aspergillus indicates a high moisture content. The 

 reason green mould does not usually api)ear upon copra with 

 a high degree of moisture is because of its slow rate of 

 growth. The spores germinate in hanging drops in about 

 six and a half hours, but the subsei|uent growth is slow, and 

 colonies upon copra do not become visible to the naked ej-e 

 until from about twenty-four to thirty six hours after the 

 sjxires are placed upon it. The colony grows very slowly, 

 and mature colonies from a single ajwre are hardly ever more 

 than 1 c,c. in diameter. The spores are mature in abont 

 eleven hours after the mycelium becomes visible. Due to 

 the nuich more rapid growth of the other moulds, Penicillium 

 is either crowded out or covered over by them, and under high 

 moisture conditions it is only after the other moulds have 

 stoiiped growing that Penicillium becomes visible. 



