Vol. VIII. Xo. 191. 



THE AGRICULTURAL NEWS. 



2(53 



INJURY TO RUBBER TREES BY TAPPING. 



The results of an investigation conducted by 

 Professor Fitting, of the University of Tubingen, at 

 the Botanic Gardens of Buitenzorg, into the physio- 

 logical principles which underlie the ways in which the 

 best methods of rubber-tapping may be found, is given 

 in a supplementary number of Tropenjitianzer for 

 February 1909. These were briefly indicated in the 

 Agricultural Neivs, Vol. VIII, p. 212. ;A more detailed 

 account may be given as follows : — ■ 1 



Attention i.s drawn to the fact that the part of a rubber 

 tree which is commonly called the bark is not only the place 

 where latex is formed and stored, but that it serves a more 

 important piu-pose from the point of view of the life of the 

 plant. The food which is elaborated in the leaves would be 

 useless unless there was some means by which it could be 

 •carried to those parts where it is reipiired, such as the 

 regions of vegetative growth, the chief of these being the 

 leaf-buds, the cambium and the root ends, and of reproductive 

 growth, that is where flowers, fruits and seeds are being 

 formed. The transference is effected through tubes in the 

 bast, or what is usually known as the inner part of the 

 bark. In these tubes, as long as the plant is actively growing, 

 there is a current of food passing along the branches to the 

 main stem, and down the stem to the roots. 



In considering the effects of tapping, there has been 

 a tendency in the jjast to forget that injury may be done to 

 this important food-conducting system of the tree. The 

 greatest attention has been given to the cambium layer, as it 

 was well I'ecognized that any extensive injury to that part of 

 the tissue would result in retardation of the growth of the 

 tree, or even in its death, either from direut causes or owing 

 to the admission of fungi. Perhaps the reason \vhy so much 

 Attention was given to this tissue was that there was a full 

 recognition of its importance as the actively growing part of 

 the stem, and it is for the same cause that, in considering tlie 

 value of different methods of tapping, attention was not given 

 only to their efficiency in producing the greatest quantity of 

 latex with the least amount of labour, but also to the likeli- 

 liood of their causing damage to the cambium layer. This 

 •consideration is, of course, important, but the one in which 

 <iccount is taken of the method of the transportation of 

 •elaborated food, which is explained above, is equally so. If 

 the tree is to attain its best growth it must be well supplied 

 with roots. If roots are to grow, they in their turn nuist be 

 well supplied with food. They cannot thrive directly on the 

 mineral plant food which they aljsorb ; they nm.st be fed 

 freely and easily from the food which has been prepared in 

 the leaves, therefore there must be nothing to interfere 

 seriously with the carriage of this food from the place where 

 it is made to that where it is required. ■. This is why, if 

 a fairly wide strip of bark has been removed from all round 

 a tree, as deep as the cambium, the plant eventually dies. 



In the methods of tapping which arc commonly enqjloyed, 

 a sloping cut is made which, although it does not reach the 

 cambium, goes far to check the downward current : this is 

 •especially so if the pricker is used as well as the knife. It 

 follows naturally that the amount of obstruction varies 

 ■directly with the width of the area operated on. The prac- 

 tical application of this consideration is simple. It will lead 

 to the adoption of those methods which involve the cutting 

 of the bark in such a way that the longest effective cut is 

 made with the least severing of the bast tubes in their vertical 

 course through the stem. This condition is fulfilled by the 

 herring-bone and half herring-bone .systems, as these only affect 

 a quarter of the circumference of the tree in any one tapping. 



VITALITY OP WEED SEEDS IN MANURE, 



The following information, obtained from the 

 Maryland St<dii>n i?«/fc///?,, Xo. 128, appears in Far- 

 mers' Bulletin, No. SS-l, of the United States Depart- 

 ment of Agriculture : — 



It is well known that tiiere is considerable risk of intro- 

 ducing new weeds by the purchase (if manure, hay, and 

 other feeding stutt's. At the .Maryland Station more definite 

 information on this point was obtained, especially as regards 

 dissemination through manure, by studying the effect of the 

 fermentation of manure handled in different ways, and of 

 passing through the digestive systems of animals, on the 

 vitality of various weed seeds, including seeds of about fifty 

 of the worst weeds found in ilaryland. 



In experiments in which the manure remained (1) for 

 six months in a barnyard heap, and (2) for a short while in 

 piles as when shipped in carload lots from cities, it was found 

 that in the first case there was no danger, and in the second 

 case little danger, of distributing live weed seeds. In the 

 experiments in which the weed seeds were fed to yearling 

 steers, and the manure handled in A-arious ways, it was found 

 that : — 



(1) AVhere the manure was hauled directly from the 

 stable as a top dressing, an average of only iLi'S per cent, of 

 the seeds fed to animals gernnnated. 



(2) Where manure was hauled directly from the stable 

 upon the land and ploughed imder, 2-3 per cent, of the seeds 

 fed to animals came. up. 



(.3) Where the droiipings remained in the pasture field.-* 

 unadulterated as they fell, an average of oillj^ 3'1 per cent, 

 of the seeds fed to animals germinated. 



The results indicate that, in general, it is safe to 

 assume that the vitality of weed seeds is destroyed in 

 well-rotted manure, but that many pass unharmed 

 through the digestive tracts of animals, and may be 

 carried to the land if the manure is not well rotted 

 before use. 



TIME OF GROWTH AND RIPENING 



OF CACAO PODS. 



The account of the follovving observations on the 

 time of growth and ripening of a cacao pod, which 

 were made in Trinidad, appears in the Bulletin of 

 Agricultural Information, of the Department of 

 Agriculture in that island : — | 



The first appearance of the fruit was made on July 1 7, 

 when it was about as large as the head of a pin. In twenty- 

 nine and forty-five days, respectively, it was 1 1 inches long 

 and 3 inches long, while in sixty-one days the length was 

 ■tl inches and the largest circumference 5 inches. Three 

 more measurements, made in seventy-six, ninety-four, and 



107 days from the commencement, gave 



inches 



7 inches and 8 inches for the length, and 7 inches, 

 9f inches and 13 inches for the circumference. Xo growth 

 was observed after the 107th day, and the fruit took thirty- 

 five days more to ripen, making 112 days in all for its full 

 development. 



As is pointed out, during this period of about two- 

 fifths of a year, while the cacao pod is arriving afe 

 maturity, it i« exposed to insect and fungus attacks, so 

 that the necessity for good sanitation on cacao estates 

 is triade very evident." 



