and Magazine of the Ceylon Agricultural Society.— September, 1912. 2Gl 



long. They are dark-brown or black and oval 

 in shape. 



Leaves which are attacked by this scale are 

 discoloured by a blackish or brown fungus 

 which follows upon this insect. The fungus- 

 hives the sugary exudation of the scale. 



Trees which have this scale upon them often 

 swarm with ants, whose habit it is to live in close 

 connection with many species of scales on ac- 

 count of the exudation from them being agree- 

 able to the ants. Attacked trees may sometimes 

 be detected by the presence of ants. 



In cases where large areas are affectel it is 

 advisable to commence catching the pest immedi- 

 ately after wintering. It is easier to deal with it 

 at this time as large numbers die at the winter- 

 ing period. Where small areas are affected it 

 often happens that there is no return after win- 

 tering. Should spraying prove necessary either 

 kerosene or resin would prove effective. 



Disease of Rubber. 



The following diseases audEconditions of Para 

 rubber have received attention from the Myco- 

 logical staff during the year. Owing to Mr Bate- 

 son being on duty in Krian the greater part of 

 this work has fallen to Mr Bancroft, Assistant 

 Mycologist. 



Root Diseases. — (i) The disease caused by 

 Fomes semitotus still constitutes the most impor- 

 tant disease of the plant and continues to 

 cause a loss of trees in young plantations. It 

 has proved itself amenable to methods of 

 treatment by isolation, sanitation of diseased 

 trees, application of lime. The majority of es- 

 tates are free from the disease among their 

 old rubber. It has been shown in the investiga- 

 tions that one of the most important considera- 

 tions in connection with the treatment of the dis- 

 ease is the application of anefficient system of drai- 

 nage. The trenches which were used for isolating 

 the diseased areas were, in several cases, found 

 to be too small, and it was recommended that 

 they should be made to include, not only the 

 trees which were attacked, but the next row of 

 trees beyond, so that a large area might be 

 marked out for treatment. After studying the 

 number of plants on which the fungus occurred 

 it was concluded that a selective method of 

 stumping would not be practicable as a preven- 

 tive measure. The observations on the disease 

 in the field appeared to justify the conclusion 

 that only under exceptional circumstances, is 

 the damage done by the fungus sufficient- 

 ly great to warrant the complete removal 

 of the timber from the land ; while there 

 is sufficient evidence to demonstrate that the 

 disease can be exterminated by treating infected 

 areas as soon as they are discovered. 



(ii) The " brown root disease," caused by 

 Hymenochaste noxia, occurs only in small quantity 

 in the Federated Malay States. It was recorded 

 on fifteen estates in different planting districts 

 during the year, a few trees usually being at- 

 tacked on each estate. It has been found that 

 the fungus grows very slowly, and does not 

 spread through the soil even under damp con- 

 ditions; and consequently its action is usually 

 limited to a single tree, Isolation, by trenches 



and liming, accordingly appear J to be un- 

 necessary, providing that the dead roots 

 are removed. The disease is consequently 

 much cheaper to treat than that caused by 

 Fomes semitostus. 



No other root diseases have been found to 

 occur in this country. Irpex flavus, which has 

 been said to cause a root disease of the plant, 

 has hitherto been recorded only as a saprophyte 

 on dead wood. This fungus has been said to kill 

 clove trees in Malacca and also to cause a root 

 disease of coffee. The fungus known as Holicoba- 

 sidium mompa, which is said to be a root para- 

 site on Para rubber, has not been met with ; it 

 has possibly been confused with Hymenochaste 

 noxia, the " brown root fungus.'' A root 

 disease reported from Oeylon as being due to 

 Spxhrostilbe repens has not been recorded in 

 this country. 



Stem Disease.— (i) The "die-back disease," 

 caused by the DipLodia form of the fungus, 

 Thyridaria tarda, has been met with com- 

 monly during the year. Its action is limi- 

 ted to a branch or a tree here and there. 

 The fungus occurs commonly on dead 

 branches, whatever may have been the cause 

 of death ; and consequently the death of 

 branches from shade or natural causes is fre- 

 quently attributed to it. The fungus must en- 

 ter through a dead or wounded part of the plant 

 and such fungi are not usually a virulent source 

 of disease. Following on another fungus, which 

 attacks the young plants and which will be men- 

 tioned later, the die-back fungus has been res- 

 ponsible for some considerable damage. The 

 methods of treatment are the sealing of wounds, 

 the removal of attacked branches and the estab- 

 lishing Of a vigorous growth of the plant. 

 Spraying as a method of treatment is entirely 

 unnecessary. 



(ii) The death of the tips of the shoot of 

 young trees has been found by inoculations 

 to be due to a fungus, which appears from its 

 characters to be indistinguishable from PhM- 

 losticta ramicola, previously described from 

 Ceylon but not regarded as a parasite. It has 

 been recorded on several estates and the 

 extent of the damage done is indicated thus :— 



Date of No. of 



record. trees. Area. Age of trees 



15-7*H 35 4 acres. 6 months 



20-7-11 6 2 acres 15 months 



20-7-11 2 (Adjacent trees) 18 months 



25-8-11 36 1 acre 2 years 



20-10-11 4 (Not known) (Not known) 



12-12-11 50 5 acres 18 months 



The disease was first observed in July. 

 The fungus attacks only the upper parts 

 of the branches, usually the topmost 12 or 

 18 inches; but sometimes the uppermost three 

 feet may be affectel The " dieback " fungus 

 follows readily after this preliminary attack and 

 may kill the tree to its base. An area of four 

 acres on which 35 trees svere affected was treated 

 by cutting off the dead parts and burning them, 

 sealing the wounds with a mixture of coaltar 

 and clay and spraying every tree in the whole 

 area with a boiled lime-sulphur mixture as % 



