154 



[August, 1912. 



are not so very different from those in 

 Ceylon after all. But the difficulty is 

 that to the planter all " white ants " are 

 the same. 



Results of Observations. 

 Observations with regard to the spread 

 of the mycelium are summarised as 

 follows :— 



" (1.) The mycelium of the fungus appears 

 to show no appreciable capacity for 

 resting in the soil when its normal 

 source of food supply has been removed » 

 when the growing mycelium is unable to 

 come into contact with living or dead 

 roots or when the soil containing the 

 mycelium is cleaned of roots and timber, 

 the mycelium soon dies out. 



(2.) The disease can be spread by the 

 growth of the mycelium from infected 

 to healthy roots ; the mycelium occurs 

 on the roots of dead jungle trees which 

 thus provide a source of infection in the 

 planted area. The mycelium grows most 

 rapidly where the material is dying or 

 but recently dead, and the danger of 

 infection is greatest where there is an 

 abundance of such material in the land, 

 i.e., immediately after the jungle has 

 been felled and burnt. 



(3.) Damp conditions favour the 

 growth of the mycelium. 



(4.) The mycelium occurs in greater 

 quantity in the uppermost eighteen 

 inches of the soil, but it can occur at 

 greater depths and has been recorded at 

 a distance of three and a half feet below 

 the surface of the ground. 



(5.) The disease makes its appearance 

 usually at the end of a year or eighteen 

 months after the area has been planted. 

 The fungus can, however, infect younger 

 plants, and it has been found that in- 

 fected plants have sometimes been trans- 

 ferred from the nursery to the field. 



(6.) The disease can be reproduced 

 artificially by the growth of strands of 

 mycelium from infected to healthy roots, 

 which is concluded to be the usual mode 

 of infection in the field. 



Z (7.) The time-rate of death of the 

 plant from the disease is not easy to 



determine accurately ; but such obser- 

 vations as have been made tend to 

 show that plants of one or two years of 

 age succumb to the disease usually with- 

 in four to eight months after they are 

 attacked. Older plants may live on for 

 a longer time. It is estimated for old 

 trees that two years may elapse before 

 they succumb to the disease." 



Recommendations. 



Bancroft recommends that a trench, 

 two and a half feet deep should be dug 

 round an infected area. When a single 

 tree dies from the root disease the trench 

 should in most cases, include not only 

 the dead tree but the eight trees ad- 

 jacent to it. The lateral roots of these 

 surrounding trees should be examined, 

 and cut off if found diseased. All dead 

 wood must be dug out from the area 

 isolated and burnt on the spot. When 

 the area enclosed has been dug over 

 once, it is advisable to dig over a second 

 time at an interval of about a mouth 

 and to turn in lime at the rate of 25 lbs. 

 for every 100 sq. feet. " The time of 

 'supplying' depends upon whether the 

 dead wood has been properly removed 

 or not. It has been found that where 

 the infected areas have been dug over a 

 second time and limed and the work has 

 been carefully done the 'supplies' can 

 be put in within a few weeks." " Gener- 

 ally speaking, supplying is done up to 

 the sixth or seventh year." 



On the question of 



REMOVING ALL TIMBER 



from Hevea plantations, Bancroft's views 

 are somewhat at variance with the 

 current policy of indiscriminate removal 

 of everything. On this point anyone 

 interested in Malayan plantations should 

 consult the Bulletin for the full evidence 

 on which the author's views are based. 

 "There appears to be sufficient evidence 

 to show that the disease can be success- 

 fully eradicated if careful attention is 

 paid to the treatment of the infected 

 areas or centres of infection, although 

 the bulk of the timber be allowed to 

 remain. 



THE COMPLETE REMOVAL OP TIMBER 



from the land would appear in moat 



