and Magazine of the Ceylon Agricultural Society. 



379 



periods. The dry weather period is smooth and 

 in the wet weather the tapping is rough. The 

 bark is up and down. It has been injured by the 

 caDker. This renewal of bark over the diseased 

 portion 



WILL SPOIL YOUR ESTIMATES. 



Are you going to restrict your tapping to the 

 dry weather period in order to provide a smooth 

 renewed bark ? 



Mr Martin: — Is any permanent injury done? 



Mr Petch :— The permanent injury done is 

 that the renewed surface is rough. 



Mr Bamforth:— Is that all ? 



Mr Petch;— That is the biggest all (laughter). 

 That is the biggest question with regard to the 

 Rubber Industry at the present time. You get 

 trees tapped, say, the first round in four years. 

 Some of them will have smooth bark, but some, 

 especially if canker is present, will be rough, 

 and you cannot tap that with an ordinary knife. 

 You may do it with another system. 



Mr Baines:— You can tap it with the present 

 knife ? 



Mr Petoh:— You cannot; and this will make a 

 big difference in the estimates, where you have 

 a hundred trees or so rough barked. When you 

 go to tap your treesthe second time you will find 

 you cannot do it with the ordinary system; and 

 probably where you came back the third time 

 you would find a few more trees rough-barked. 

 The number is ever increasing; and how long can 

 you go on ? 



Mr Masefield:— Has this particular kind of 

 canker appeared in the Matale-Kurunegala 

 districts. 



Mr Petch :— I have not had any canker from 

 tapping from Matale. But it is all over the low- 

 country districts. The time will come ultimately 

 when you will have 50 per cent, of jour trees 

 rough barked ; then you 



WILL HAVE TO ADOPT ANOTHER SYSTEM OF TAPPING. 



The obvious thing is to make your first bark 

 last as long as possible. 



jyir Mitchell :— Otherwise do not tap in wet 

 weather. 



Mr Petch :— No ; that won't meet the diffi- 

 culty. 



Mr Williamson :— You have a new system ? 

 Mr Petch :— When I have a 



NEW SYSTEM I WILL SELL IT. 



(Laughter.) The rough bark i3 in a small 

 percentage, but it is actually happening. There 

 are a good many rough barked trees in your 

 second tapping, but youicauhack and collect the 

 scrap. 



Mr Kyn aston :— Though the bark is rough, 

 you can tap. 



Mr Petch : — That is a question for you to 

 decide. It has been suggested that this can- 

 ker, as it comes on only in wet weather, is due 

 to rain lodging in cuts. The things we get out 

 of it in the laboratory are just the same as 

 we got out from the canker of 1903. If you take 

 a section of a tree and examine it in the proper 

 way you will first 



get a large quantity of bacteria, 

 and the second organism will be the nectria fun- 

 gus. I have bacteria grown in beef tea end other 

 media and got the nectria sporcu to germinate 



and grow in solutions and made inocu- 

 lations of trees at Peradeniya with pure cultures 

 of the bacteria and the nectria. This was done 

 three weeks ago and up to the present there 

 have been no signs whether they are going to 

 have canker. So we cannot say yet whether it 

 is due to the rain getting in — whether that is 

 the most likely cause— or the organisms getting 

 in. I think it is due to the bacteria getting in. 

 Of course, the old advice to deal with the canker 

 is to cut out all the dead bark. You will probably 

 get a smoother renewal if you cut out your 

 decayed bark than if you leave the old bark 

 to renew itself. There is no need to stop tapping 

 because of the canker, as you can get the latex 

 with the disease present. You can go on tapping 

 the whole time. I am inclined to say: cut out 

 the diseased bark, and 



sterilise all your tapping tools. 

 As tar as we can see— on some estates I have been 

 to — you carry tho infection from one tree to 

 another by the tapping knife. If you only 

 get one cankered tree or two, the best thing 

 to do is to leave those trees alone. But when 

 you have 50 per cent of the trees affected, 

 it is impossible to leave them alone. Steri- 

 lising the tapping knife is easily done 

 by dipping it in one part to 1,U00 of cor- 

 rosive sublimate and leaving it there 5 minutes, 

 which is ample. That will kill any bacteria on 

 the knives, but it will only be effective where you 

 start tapping on a new clearing. If you sterilise 

 your knives and go on to infected trees next day 

 your sterilising will be of no avail. On the whole 

 it is rather difficult to know what to advise in a 

 case of canker. Certainly I will not advise to 

 stop tapping. (Laughter.) 



Mr Masefield :— vVith regard to the treat- 

 ment of canker will you put tar on or leave it 

 alone ? 



Mr Petch :— No ; do not ; leave it alone. 



Mr Masefield :— Will you cut it out? 



Mr Petch :— If you cut out you must remove 

 everything that is black. The specimen here 

 (shown) shows black round the cambium. I 

 would not cut into the wood. There is 



no need to hack into the wood. 

 It is a question of judgment as to what you 

 would cut out and what you would leave alone. 



Mr Bamforth : — Is there any danger of the 

 canker spreading ? It is better to leave the tree 

 alone or cut it out 1 



Mr Petch :— Certainly leave the tree alone, but 

 it all depends on the number of trees you have 

 got. (Laughter.) If you have two or three 

 cankered trees, you should leave them 



out of the tapping round. 

 You could cut out the diseased bark and 

 leave the trees out of the tapping round. 

 Even if you do not cut out the diseased 

 bark, I do not think you will spread the 

 infection if the trees are left alone. I 

 am pretty certain that infection is carried, 

 say from one cankered tree you have, by the 

 cooly who taps that and goes on to the next. 

 You find the cankered trees spreading gradually 

 down the line from thefirst diseased tree. 



Mr Martin :— Will it cease to spread if yon 

 atop tapping on that side ? 



