Plant Sanitation. 



182 



[March 1907. 



the extension of theinjury to the surrounding trees. With this view I experimented 

 with the patent 'Ant Exterminator' recently received from South Africa. This 

 machine pumps a deadly gas (generated from sulphur and arsenic) through the 

 galleries, and has been found most effective in the destruction of the ordinary 

 mound-building termites. The nozzle of the machine was inserted first into the 

 exposed galleries in one of the branches, and afterwards into a hole drilled through 

 the stem inLo the main cavity. But the ventilation was insufficient, owing to the 

 blocking of the cavities with earthy matter, and it was found impossible to force the 

 fumes through the system of galleries. Other plants were collar pruned, and small 

 quantities ol vaporibe placed in the cavity which was then plugged with clay. The 

 results of this latter experiment will not be available for some weeks. 



In a former number of this Magazine (Nov. 1906, p. 396) reference was made to 

 a novel method of destroying the shot-hole borer in situ, by scorching the bushes 

 immediately after pruning. The inventor of this method is Mr. C. W. R. Tyler, of 

 Sanquhar Estate, in the Gampola district. I have now had an opportunity of seeing 

 the work in progress, and am very favorably impressed with the results. The fol- 

 lowing notes were made on the spot : — 



Gangs of women and children are supplied with torches made of dried coco- 

 nut leaves. They pass the flaming torches round each bush, beneath the branches, 

 holding them there long enough for the heat to penetrate the wood. On splitting 

 open the branches, the insects— both young and adnlt — are found to be quite dead. 

 I was able to satisfy myself of this result in the smaller ('pencil') branches. The 

 older branches, though previously badly infested, were now deserted by the insects, 

 so it was impossible to determine here whether the treatment would be equally 

 effective in these thicker branches. 1 was shown a field that had been treated in 

 this way when pruned in August of last year. The treatment was said to have been 

 applied very severely, and not a single surviving insect could then be found. A good 

 many of the smaller branches had been killed, but fresh healthy shoots were in every 

 case being thrown up from the lower parts of the bushes, promising a rapid recovery. 

 This system seems to me to be preferable to collar pruning as— while ridding the 

 plant of the pest— it affords a more rapid I'ecovery. It sliould be understood that, 

 to be of permanent value, the treatment must be carried out systematically over the 

 whole of the affected area. Otherwise re-infection from surrounding fields will occur 

 sooner or later. In the meantime, it has the advantage of bringing the plant into a 

 condition that enables it more successfully to resist the attacks of the borer. That 

 nature can and does repair the injury under favourable conditions was abundantly 

 evident on this estate. On splittiug open the more healthy free growing branches, 

 the entrance holes were repeatedly found to be plugged by an ingrowth from the 

 cambial tissues. The cost of the treatment is largely influenced by the cost of the 

 torches. On this estate the dried coconut fronds had to be bought in Kandy isome 

 13 miles distant,) and transported by rail and cart to the estate. Each torch costs, 

 on the estate, approximately two cents, and is exhausted after the treatment of eight 

 bushes. A cooly can satisfactorily treat 250 bushes for his day's name. This works 

 out at Rso 13'55 per acre ; but Mr. Tyler informs me that the actual cost is nearer 

 Rs. 11. Experiments were tried with artificial torches composed of coconut fibre, 

 kitul fibre, and old sacking— tied on sticks. These substances were steeped in kero- 

 sene oil and liquid fuel. The kitul fiore proved to he slightly the better medium, 

 but owing to the difficulty of obtaining it in sufficient quantity and at a cheap cost, 

 it must give place to coconut fibre for practicability. Our experiments showed that 

 this fibre— when properly tied will form a really useful and economical torch. The 

 fibre should be tied in a tight pad— without loose ends. Of the two oils, the heavier 

 and cheaper (liquid fuel) was found to be the more satisfactory. In application one 

 podian accompanies some five or six torch bearers, with a tin of oil and a small scoop 

 with which he replenishes the torches as the oil is exhausted. 



