Ptant Sanitation. 



224 



[September, 1910. 



root on that side had been killed by 

 Hymenochcete, and that the fungus had 

 spread into the stem. White ants had 

 then eaten out the dead root and the 

 dead wood in the stem, leaving only a 

 thin cylinder of sound wood at the base 

 of the latter, up to a height of two or 

 three feet. Evidently the consistency 

 of the latex was due to lack of water 

 because the tree did not possess a suffi- 

 cient thickness of wood at the base to 

 permit a normal supply ; and the case 

 furnishes additional evidence that the 

 available moisture influences the quality 

 of tho latex. 



Where " pink disease " caused serious 

 loss by killing off large numbers of young 

 Hevea last year, spraying the trunks, 

 or more especially the forks, with Bor- 

 deaux mixture before the monsoon was 

 recommended. This treatment has been 

 carried out on one estate in Southern 

 India, and details of the cost have been 

 published in the Planters' Chronicle, 

 May 21, 1910. The mixture was applied 

 with a brush, and painted on where the 

 branches joined the main stem. The 

 cost of treating 500 acres was Rs.150, 

 but 200 acres consisted of young trees, 2\ 

 year old, and cost very little. It would 

 certainly pay to adopt this treatment on 

 areas where ' ' pink disease " reappears 

 periodically. As a rule, the disease, 

 in Ceylon, is not spread over the whole 

 estate, but occurs in certain patches. If 

 the trees on fields which are known to 

 be liable to infection were treated in the 

 manner indicated prior to the south-west 

 monsoon, much loss would be prevented. 

 While the disease does not cause any 

 widespread damage in Ceylon, the trees 

 attacked are usually six to eight years 

 old, and it is certainly worth while to 

 make some attempt to save these. Even 

 if we eliminate the 200 acres of the young 

 trees from the figures quoted above, 

 Rs. 150 for 300 acres cannot be considered 

 prohibitive. 



The application of Bordeaux mixture 

 with a brush is practicable in such a 

 case, and of course that method obviates 

 any large initial outlay on sprayers. 

 But it may be doubted whether it is 

 really cheaper than spraying in the end. 

 It has been found, in Southern India, 

 that the cooly cannot, or will not, work 

 a sprayer if he has to pump with one 

 hand and direct the spray with the 

 other. The same thing happened on the 

 Experiment Station, Gangaruwa ; and 

 for that reason, a sprayer worked by 

 compressed air was adopted. But where 



the ground is level, barrel pumps are 

 preferable to knapsack sprayers. The 

 knapsack sprayer in use at Gangaruwa 

 only holds a gallon, and requrres to be 

 filled six times a day. The time occupied 

 in filling is almost equal to that occupied 

 in actual spraying, so that the work 

 would be done in about half the time it 

 barrel sprayers could be used. 



It has been gravely announced in one 

 agiicultural journal that, in Ceylon, 

 tomes semitostus attacks Crotalarta. 

 The information is, of course, incorrect. 

 It is probably based on the announce- 

 ment in the "Tropical Agriculturist . 

 that Corticium javanicum had been 

 found on Crotalaria in Southern India ; 

 and it serves to illustrate the ^extraor- 

 dinary manner in which "facts" relating 

 to tropical agriculture are produced. 



It has been suggested by a correspon- 

 dent whose Hevea trees, grown at a 

 fairly high elevation, appeared some- 

 what " hidebound," that they would be 

 improved by rubbing off the outer layer 

 of dead bark. It is not probable that 

 such a treatment would have any effect, 

 since the layer in question is thin, and 

 usually cracked, and does not exert any 

 pressure on the tissues beneath. An 

 application of manure would seem to be 

 indicated. There appears to be an idea 

 current that rubbing off the outer bark 

 will " irritate " a tree, and cause it to 

 increase its girth more rapidly. But, 

 apart from the fact that " irritation" of 

 this description is unknown in plants 

 (except, perhaps, in certain tendrils), it 

 will readily be seen that such a process 

 could not affect the cambium which is 

 responsible for the growth in thickness. 

 The only result of rubbing off the layer 

 of dead bark would be that the tree 

 would produce another layer at the ex- 

 pense of the laticiferous tissue, as is 

 evident when a tree is scraped. 



A consignment of disease specimens 

 recently received from the Gold Coast 

 provides further demonstration of what 

 is yearly becoming more and more 

 certain, viz., that the diseases of cultivat- 

 ed plants are caused by the same species 

 of fungi throughout the tropics, though 

 the truth has been obscured either by 

 attributing them to the wrong fungus 

 or by giving the same fungus different 

 names in different countries. A rcot 

 disease of Funtumia was clearly caused 

 by Hymenocha3te noxia, and a root dis- 

 ease of Hevea showed a mycelium which 



