74 The Supplement to the Tropical Agriculturist 



husk or the leaf stalk after it had fallen, or the 

 tissues in the bud. The fungus grew, as he 

 said, on the tissues of the coconut which 

 contained sugar. As a matter of fact they had 

 to grow it in a solution of sugar before they 

 could get it to germinate at all. He bad there 

 aflask in which was some of the fungus in a solu- 

 tion of sugar. 



(The flask was handed round for the inspec- 

 tion of the Chairman and members.) 



If they sowed the spores in pure water, 

 or in ordinary tap water, they would not 

 grow at all. Another point about the growth 

 was that it would grow very much better in 

 darkness than in light. Many fungi would grow 

 better in darkness than in light, but they 

 produced spores only in the light. Thielaviopsis 

 formed a very much greater weight of spores in 

 the darkness than in the light. In about a week 

 they got 50 per cent, greater growth in darkness 

 than in light. They could not get the spores 

 to germinate in the absence of oxygen. 



The question as to 



HOW LONG SPOKES WOULD RETAIN THEIR 

 GEMINATING CAPACITY 



was rather an important one, but the experiments 

 were not altogether finished. In one experiment 

 spores were distributed over a filter paper or 

 rather a series of about a dozen niter papers; 

 then the papers were exposed under different 

 conditions. Two sets were dried in a desiccator 

 and two sets by exposure to the air ; one of 

 each was placed in the sunlight and the other 

 left in the dark. Calling the air dried spores 

 damp, as they possibly would be, the damp spores 

 were killed by the sunlight of about three 

 hours a day in less than a fortnight, whereas the 

 perfectly dried spores exposed to the sunlight re- 

 tained their vitality for ten weeks. If the spores 

 were kept in the dark, they retained their 

 germinative capacity longer. An experiment 

 was begun at the end of November last year, 

 and the spores kept in the dark were not 

 dead yet; so there was a great difference in the 

 germination of the spores kept in darkness from 

 those exposed to sunlight. That, on estates, 

 might be an important point. He had taken 

 black patches from the trees and tested the 

 spores in the black patches. Of course there 

 was no knowing how long the spores had been 

 on the tree ; they might have been there two 

 months or two years. In patches obtained 

 from Batticaloa he did not get a single germi- 

 nation in three cases, and in the case of patches 

 from Kalutara he got one germination out of 

 three. It might, therefore, be taken that in cases 

 of ordinary estates where the sunlight reached 

 the trees most of the spores were quickly killed 

 by the sunshine. The other experiment he re- 

 ferred to was to find out how long the spores 

 would take to die if they were dried in the sun- 

 light. This had not yet been determined. 



THE EFFECT OF VARIOUS CHEMICALS ON THE 

 FUNGUS 



was tried. Copper sulphate was recommended 

 last year, and carbolic acid was suggested, as 

 well as various other agents. In testing that ques- 

 tion the fungus spores were placed in a flask, 



in a solution in which they would grow, and then 

 a certain percentage of the chemical was 

 added. A chemical had not a poisonous effect 

 unless it would stop the growth of the fungus 

 with about one per cent. If they had to use five 

 per cent, there was no poisonous action. Potas- 

 sium nitrate was recommended, but the fungus 

 would grow in 12 per cent, of potassium nitrate 

 and was stopped by 13, so they could put that 

 out as a fungicide. Kainit was strongly re- 

 commended. The fungus would grow in a 

 solution of 13 per cent. It stopped at 14 per 

 cent, so that the fungicidal action in that case 

 was absolutely nil. Common salt, that was the 

 ordinary dry cooking salt, stopped the growth of 

 the fungus at seven per cent. If they took 

 sodium chloride instead of common salt, the 

 growth stopped at six per cent., a slight im- 

 provement. It was thought that the magnesium 

 salts might have some action and so magnesium 

 sulphate was tried. He found that the fungus 

 would grow in a solution containing 25 per cent, 

 of magnesium sulphate, so he stopped that and 

 did not go any further. By the rate it was gro- 

 wing it would possibly have grown in a solution 

 containing 50 per cent. Chloride ought to have 

 been tried, but he had not got it. Caustic 

 potash and caustic soda both stopped the 

 growth as soon as the solution became alkaline. 

 This fungus would grow in acid solution, but not 

 at all in alkali solution. Tannic acid gave a pecu- 

 liar result, the growth of the fungus being 

 stopped by "3 per cent, of tannic acid. It was 

 thought that that might explain the fact that the 

 fungus did not grow in the cabbage of the coco- 

 nut, but there was no tannic acid even in the 

 cabbage. 



With regard to the poisons, copper sulphate 

 stopped the growth of the fungus at - 04 per 

 cent., 4 parts in 10,000, whereas the other 

 chemical recommended, carbolic acid, only 

 stopped the growth at *1 per cent., one part in a 

 thousand, so that as far as stopping the growth 

 was concerned carbolic acid was very much 

 behind copper sulphate, but it had a great 

 advantage in one respect, in that it killed the 

 spores very much sooner than copper sulphate. 



The figures he had been giving them re- 

 lated to the stoppage of the growth of the 

 fungus, but the 



ABSOLUTE KILLING OF THE SPORES 



was quite a different matter. They might find 

 that the spores would not grow in a solution 

 containing so much per cent, of tannic acid; but 

 if they took them out of that solution, and put 

 them in another without tannic acid then they 

 would grow. Tannic acid did not kill them ; it 

 simply stopped the growth. "1 per cent, 

 carbolic acid did not kill the spores, but it 

 stopped their growth. When they tried to find 

 what percentage killed the spores, they dis- 

 covered that one per cent, of carbolic absolutely 

 killed them in a day, whereas one per cent, of 

 copper sulphate would not kill them in a month. 

 In fact he had spores in a five per cent, copper 

 sulphate solution which were not dead in seven 

 weeks ; so that the best thing for killing the 

 spores was carbolic acid. Unfortunately they 

 could not use it because it could not be applied 

 with safety to the tree. 



