589 



us threads appear to move faster up the stem than down it, and 

 generally have not reached the collar before the disease is noticed, 

 when this is the case there is no need to destroy the plant. The 

 diseased portion can be easily recognised by the black colour of the root 

 and wood. The stem should be cut off in the sound tissue above the 

 collar, and the wounds covered with tar. If the old stump had been 

 tarred very likely the disease would never have appeared. The same 

 disease has been found on old trees which had been peeled by animals 

 in some cases, in others scorched by fire. When one remembers that 

 for the first year of its life the young para plant is growing among a 

 crowd of dead stumps and stems covered with fungi, luckily for the 

 most part harmless, but liable to include kinds which have the faculty 

 of becoming parasitic, the planter cannot be too watchful of wounds, 

 and should take measures to cover all of any size, stump wounds, includ- 

 ed, with tar. 



Among other pathological appearances must be mentioned the oc- 

 currence of huge " knots" or " burrs" on old trees. They are stated 

 not to appear until the tree has been tapped. The appearance is like 

 a malformed development of a dormant bud. It looks like a much 

 flattened deformed branch, up to nine inches in width and three to four 

 feet in length, growing up the stem and covering the true bark, from 

 which it may usually be prised back. It reduces the tappable area 

 considerably as the bark on the malformation contains little or no la- 

 tex. An investigation of this interesting but undesirable phenomenon, 

 with the hope of successfully combating it, is in progress. 



Disease has been observed on various other plants, the most 

 widely spread being a bacterial disease of mangosteens ; about 25 per 

 cent, of fruits are attacked. It has made no great headway at the time 

 the fruit is ripe, when it may be noticed as a yellow matter on some or 

 all of the seeds on opening the fruit. It is of no great consequence at 

 present owing to the consumption of the mangosteen being purely 

 local. 



Helmintkospomm, sp. was found on rice sent in, but was not the 

 cause of its lack of health. 



Defective drainage was in a few instances the cause of considera- 

 ble mortality among para trees. The para rubber tree appears to 

 adapt itself fairly well to its surroundings, but it suffers in 

 a badly drained soil; stagnant water prevents soil aeration and 

 the root is suffocated. The growing point or top dies back, bran- 

 ches shoot out much as if the plant had been thumb-nailed pruned, 

 but never develop far, the leaves scorch from the tip downwards and 

 fall off. The root has a character of its own. Plants put out in an 

 ill-drained soil show several short parallel roots running down from 

 where the root had been stumped. Probably in many peaty soils an 

 excess of humous acids acts injuriously. The anatomy of plants, like 

 heaths, which grow naturally in such soils, is so arranged that the 

 leaves give out a minimum of moisture to the air, and take correspon- 

 dingly little from the soil. The para rubber tree has almost the 

 opposite character. It would be no doubt good practice in such soils 

 to lime the holes made for the " stumps," and to fork in lime about six 

 months afterwards. The ash of the burned jungle neutralises the acidi- 



