152 PARA RUBBER. 



A dead stump may he attacked above or just below the ground, and 

 the mycelium spreading along the decaying roots may come into 

 contact with those of a living tree, and so the attack is spread. 

 These contagious fungi are more easy to deal with than the infec- 

 tious ones of which the spores are blown from tree to tree and 

 attack the plant where they alight (as in the fungus previously de- 

 scribed). The infected trees should be destroyed and the roots dug 

 out, every bit of dead root or decayed timber being removed and 

 the ground well saturated with copper sulphate and lime. 



"Tubeuf, in writing of a similar parasite in Europe (Fomes an- 

 nosus) whose habits are very similar to those of F. semitostus, states 

 that the best way of combating the ravages of the parasite is isolation 

 of infected areas. These should be isolated with ditches with vertical 

 sides deep enough to cut through all roots, care being taken to leave 

 no diseased stems or roots outside the circle. After remaining 

 open for a time the ditch must be filled again with soil to prevent 

 the formation of sporophores on the exposed roots. All diseased 

 stems should be felled and burnt, or deeply covered with soil to pre- 

 vent the formation of sporophores; in fact, isolation of these 

 contagious parasites should be done by ditches in the same way as the 

 infectious parasites are isolated by screens of trees of another 

 species." In the opinion of Mr. H. N. Ridley, Director, Botanic Gar- 

 dens, Singapore, this is one of the most important diseases in the 

 Straits on Para rubber, and deserves prompt attention. 



As Messrs. Ridley and Derry have pointed out, this fungus, the 

 mycelium of which is underground, is the worst feature against 

 close planting, as under such conditions it might spread very rapidly. 

 The uprooting of all dead stumps of trees would appear to be 

 necessary if this disease is to be kept in check. 



A fungus (Helicobasidium sps.) has been found attacking the roots 

 of Para rubber in the Straits.* This fungus usually spreads rapidly 

 from tree to tree by means of strands of mycelium, and trenching 

 and liming are generally recommended as preventive measures. 



Another root disease has been found in Ceylon by Petch.f 

 This one has also been found on cacao, tea, and Caravonica cotton in 

 Ceylon, but is not very dangerous. " The roots are covered with 

 a thick yellowish- brown felt which sometimes develops a black crust 

 exteriorly. Stone, sand, &c, are firmly attached to this covering, 

 and give the appearance of pudding-stone." It is believed to be a 

 species of Hymen ochsete. 



Insect Pests. — " Specimens of Termites! (T. redemanni) have been 

 sent with the report that they were eating off the tap roots of young- 

 rubber plants. A mixture of lime and sulphur, forked into the soil 

 immediately round the plants, has been found effective in preventing 

 the attacks of white ants. The proportions are one part powdered 



* Johnson, 1. c. p. 29. 



f T. Petch, Mycological Notes, Tropical Agriculturist, October, 1905. 



| E.E. Green, Entomological Notes, Tropical Agriculturist, April, 1905. 



