286 



The Supplement to the Tropical Agriculturist 



tree about 15 years old. I was able to get a 

 good supply of material with the fungus ac- 

 tively growing in it, because I found a planter 

 who did not object to cut down a diseased tree 

 when it was in good bearing. I made four in- 

 oculations. One of these was spoilt, the infect- 

 ing material being pulled out, probably by 

 squirrels or rats. The second was made with 

 the yellow decaying tissue in which the fungus 

 is growing most actively ; the third was made 

 with the dark brown tissue in which the fungus has 

 stopped growing but has left spores ; the fourth 

 was made with th« liquid squeezed from the 

 inside of the decaying stem. These were ex- 

 amined three months afterwards in the dry 

 season. The second has bled fairly strongly, 

 and shows a streak of red-brown liquid about 

 six inches long ; the third and fourth have bled 

 slightly. The control cut has not bled. This 

 proves that the disease can be transferred 



from one tree to another by inoculation with 

 the diseased tissue from the stem. It proves, 

 therefore, that it is 



A Real Disease 

 and not an effect of bad drainage, or too much 

 manure, or too little manure. Arid it proves 

 that it is a stem disease, not a root disease. 

 The next step was to grow the fungus in pure 

 culture, that is to separate it from other fungi 

 and bacteria, and to infect a tree with its spores. 

 Part of the diseased tissue obtained for the last 

 experiment was placed in glass dishes and the 

 fungus was allowed to develop. As the tissue 

 had been exposed, other fungi and bacteria 

 grew at the same time. Now, if inoculations 

 were made with spores from these dishes, there 

 would be a danger of introducing these other 

 fungi, and it would be impossible to tell which 

 caused the disease. We must therefore obtain 

 a cultivation of one fungus only. To do this, a 

 solution of gelatine and sugar is boiled until all 

 the organisms in it are killed ; it is then poured 

 into sterilised dishes and allowed to cool. 

 The spores of the diseased fungus are 

 then transferred to the gelantine with a 

 sterilised needle, and the dish is kept 

 covered so that no other spores can blow into 

 it. If this culture produces two or more fuDgi, 

 it is still impure, and the spores of the one re- 

 qui.' ed must bo taken from it when it fru ; ts, and 

 sown in another dish. The process must be 

 repeated until a culture is obtained which is 

 clear of 11 other fungi or bacteria. This is not 

 a .ong process in the case of the fungus of the 

 coconut disease. In the first place, it grows 

 very rapidly and fruits earlier than the 



other fungi which get into the first culture 



accidently : and secondly, it produces its 

 spores, in one form at least at the top of small 

 uptight c >luuins so that they can easily be 

 removed withour touching the gelatine. The 

 second cultivation is, with reasonable care in 

 manipulation, free from other fungi and bacteria. 



Inoculations were made with spores from 

 one of these cultures. The tree was a fairly 

 young one, but rather stunted and therefore 

 denser than the last. There was no bleeding 

 at the end of three months, but when one 

 of the infected spots was cut out, it was found 

 that 



The Disease Mad Extended 

 for about 12 square inches. A month later, 

 another spot infected at the same time began 

 to bleed. 



Returning to the old tree, infected in 1906, 

 — the infected places were cut into this year, 

 and it was found that the tissues had decayed 

 round the infections for about 4 inches, but 

 the decay did not extend into the hard wood. 

 This confirms the opinion that the disease as 

 a rule does not penetrate the dense wood of 

 old stems;. There is yet another point before 

 the proof is complete. We must recover our 

 fungus from the infected trees in order to 

 prove that the decay is not caused by some 

 other fungus which has got into the trees 

 after pur inoculation. Part of the diseased 

 tissue was cut out of the infected trees, and 

 placed in sterilised dishes : these pieces pro- 

 duced the fructification of the fungus within 

 two days. 



We find therefore that the decaying 

 tissue of bleeding trees contains a fungus ; 

 that when the spores of this fungus are 

 inserted in a sound stem, th;e stem decays and 

 bleeds, i.e., we reproduce the symptoms of the 

 disease ; that the artificially diseased stem con- 

 tains actively growing plants of the fungus 

 which we put in. Two of these trees are still in- 

 fected, and they will be left in order to see what 

 the final effect of the fungus is. These infec- 

 tions are made by cutting a piece of tissue put 

 of the stem, inserting the infected tissue or the 

 spores of the fungus, replacing the outer half of 

 the piece cut out, and then covering the cut 

 with grafting wax. In the control experiments, 

 exactly the same operations are done, but the 

 infecting material is omitted. The experiments 

 must of course bo made on healthy trees, and, if 

 possible, in a locality vvhere'there is no disease. 

 AH the cutting must be done with a sterilised 



