262 The Supplement to the Tropical Agriculturist 



preventative. The spraying was repeated at 

 the end of six weeks. Cases of the disease ap- 

 peared for the first two months after the treat- 

 ment was applied but there was no further record 

 of any cases iu the area up to the end of the 

 year. Another area of five acres is under treat- 

 ment, but there is hitherto no record of the 

 action of the treatment. 



(iii) The "pink disease," caused by Gorticium 

 salmonicolor, has been reported from ten plant- 

 ing districts. It is, however, only present in 

 small quautity, and there has been no apparent 

 necessity t j apply a preventive method ot treat- 

 ment, in order to arrest the spread of the disease, 



(iv) A "sooty mould," Limacinula jxvanica, 

 has been recorded as following on a scale insect, 

 Lecanium nigrum, on the leaves of the plant. 

 The fungus has been known on coffee in Java. 

 Its presence depends on the insect. 



(v) The "thread blight fungus 1 ' was recorded 

 on two estates. It does not appear to be pre- 

 sent in any appreciable quantity and the burning 

 of the branches has been sufficient to deal 

 with it. 



(vi) A silvery white fungus appeared on the 

 bark of trees on one estate. It appeared to do 

 no damage to the plant, but merely to disinte- 



§rate the dead bark. The trees were flooded 

 uring certain times of the year, and the fungus 

 appeared at these times near the base of the 

 trees. Jt was recommended that the trees be 

 painted with a lime-sulphur mixture ; since this 

 mixture has been found to be effective with 

 fungi of that nature. 



Leaf and Bark Diseases. 



Only two have been recorded — viz., Pliyllos- 

 ticta hevea and Pestalozzia palmarum. The 

 damage done by these two fungi is very small, 

 and even in the nurseries it does not appear to 

 warrant the application of a method of treatment. 



Several effects of somewhat different kinds 

 have been noticed on the bark of the trees. The 

 commonest is that in which areas of the bark 

 die and fall away, leaving large wounds, 

 consisting of the exposed woods surrounded 

 by a lip of renewing tissue. In such cases a 

 definite recovery takes place, and the wound 

 is healed. During the early part of the year the 

 death of the bark on the newly-tapped surface 

 was particularly common on one estate, where 

 over 1,500 trees were thus affected. Investigations 

 failed to associate the effect with my micro-orga- 

 nism and the trees eventually recovered, tapping 

 operations having been suspended. It is pro- 

 bable that this effect was due to the collecting 

 of water on the newly tapped surfaces. A similar 

 occurrence in Ceylon had been previously attri- 

 buted by Petch to the same cause. 



Another type of death of the bark occurred in 

 three trees on one estate. The bark became 

 separated from the wood by the death of the 

 cambium and could be removed in large masses. 

 The trees were about five years old. There was 

 no evidence of any root disease, An examina- 

 tion of the recently dead tissues failed to show 



the presence of any organisms. The trees were 

 removed and burnt, so there was no opportunity 

 of studying the progress of the disease. 



The hark troubles require careful investiga- 

 tion, and it is proposed to devote some attention 

 to them during the coming year. 



Shoots. 



The death of the top shoots of the plant has 

 been fairly commonly met with. It occurs on 

 exposed situations and appears in the- e cases to 

 be due to wind, or it may occur on badly drained 

 land, when it has been attributed to deficient 

 drainage. The exudation of tears of latex from 

 the brauches is commonly caused by wind. The 

 bending of the branches produces a sp itting 

 of the bark, and the latex is thus exuded 

 from the cracks. A similar occurrence is 

 said in some cases to be due to the peeking of 

 the branches by birds. Bleeding is not un- 

 commonly also associated with the " pink 

 disease." 



Malformed shoots, which take the form of 

 strap-like flattened structures, have been fre- 

 quently met with. The proportion of trees show- 

 ing these malformations is under one per cent. 

 They result from the fusion of stem and leaves 

 instead of the independent development of 

 these two organs. In some cases tbe structures 

 are large and resemble a stag's antlers. If the 

 fasciated branch is cut off or the tree pollarded 

 it will frequently throw up a normal shoot. The 

 nodular masses, which originate as small pea- 

 like bodies on the trunks and may finally deve- 

 lop into large outgrowths frequently render 

 tapping impossible. Such trees as are badly 

 burred are frequently cut. The greatest dam- 

 age from burrs is on old trees which have been 

 badly tapped in previous years. A certain 

 number of trees, however, develop burrs on tbe 

 untapped parts or before tapping has been com- 

 menced. The percentage of these latter trees 

 is, however, not usually greater than one per 

 cent or two per cent. 



Spotting of Prepared Rubber. — Consider- 

 able time was given to investigations as to the 

 causes and methods of treatment of spots on 

 prepared rubber. The result of the investiga- 

 tions have shown that the spotting is usually 

 due to the growth of micro-organisms in the 

 rubber. The organisms which have been found 

 to cause spotting are : Bacillus prodigiosus, 

 Monascus heterosporus Mycogone sp. and Spon- 

 dylocladium sp. The first of these is a bac- 

 terium, and the others are saprophytic moulds. 

 The bacterium occurs in top and pool water, 

 and consequently the infection may be ex- 

 pected to proceed primarily from this source. 

 The infection from the fungi may be expected 

 to be caused by the transfyrence of the spores 

 which are capable of being air-borne. The rubber 

 may be inoculated before or after coagulation. 

 The investigations as to the prevention of the 

 spots showed that by rapidly drying the rubber 

 the spotting could, for the most part, be pre- 

 vented from occurring. The application of 

 antiseptics and solvents did not give satis- 

 factory results. The work was nearly completed 

 at the end of the year— Pin&ng Gagette x 



