August, 1912.] 



153 



between the rows should be ploughed 

 occasionally. This is cheaper than hand- 

 hoeing, and the native plough does not 

 go deep enough to do any damage. 

 Excess of plants in the rows should be 



cut out. The difficulty in the East is to 

 get the cotton picked clean. In a hot 

 dry atmosphere dust and broken leaves 

 are hard to keep out.— (Summarised from 

 the Agricultural Journal of India.) 



ROOT DISEASE OF HEVEA. 



Fungus Parasites. 



Since 1907, practically no additions 

 have been made to the list of fungi para- 

 sitic on Hevea in the East ; and this state 

 of affairs has afforded the opportunity, 

 where few other cultivated products 

 demanded attention, for a more intensive 

 study of its known diseases. A recent 

 Bulletin, by Bancroft, the chief of the 

 mycological division of the F.M.S. 

 Department of Agriculture, on the com- 

 mon root disease caused by Fomes semi- 

 tostus, goes more deeply into the matter 

 than any previous publication, and in- 

 cludes the results of several experiments 

 on the spread of the mycelium, as well as 

 numerous observations on the action of 

 the fungus on the plant, its relation to 

 Termes gestroi, and the methods of treat- 

 ment. This, and other recent Bulletins, 

 show a marked advance in mycological 

 work in Malaya, and its planters are to 

 be congratulated upon the acquisition of 

 a mycological branch commensurate with 

 the importance of their industry. 



Bancroft states that the effects of the 

 fungus have been more severely felt on 

 the low-lying alluvial land because its 



SPREAD IS MORE ACTIVE UNDER DAMP 

 CONDITIONS, 



But he notes that its distribution 

 through the country generally is irregu- 

 lar and cannot be explained by differen- 

 ces in soil or elevation. "It is by no 

 means unusual to find on one estate a 

 death rate of 12 per cent, of trees during 

 the first few years of cultivation while 

 its immediate neighbour, possessing 

 similar soil and opened up from similar 

 jungle will yield only 2 per cent, of cases 

 of the disease during the first three or 

 four years of cultivation. 



t White- ant Attacks and Root 



Diseases. 



The correct apportionment of the 

 damage between white ants and root 

 20 



disease has long been a matter of debate. 

 In Ceylon it has always been held that 

 when white ants attack Hevea roots they 

 follow a previous attack of root disease 

 in the case of established trees, and of 

 Botryodiplodia in the case of failure of 

 " stumps." But Ceylon does not harbour 

 Termes gestroi, and consequently it has 

 been recognised that conditions in Malaya 

 were different. On this point Bancroft 

 writers : — 



"The tap root is sometimes rapidly 

 destroyed by Termes gestroi following 

 on the attack of the fungus. Both 

 Termes gestroi and the fungus are fre- 

 quently associated with each other 

 on the roots of Hevea ; the 



insect is far more rapid in its 

 action than the fungus, 

 and for this reason the destruction of 

 trees is often attributed to the insect 

 when there is good reason to believe 

 that they were first attacked by the 

 fungus. In the majority of cases in 

 which both the root fungus and white 

 ants are found attacking trees of Hevea 

 the initial attack is due to the fungus ; 

 and it would appear to be likely that 

 trees which are affected by the root 

 disease are more susceptible to attacks 

 from white ants. Trees which are pri- 

 marily attacked by the fungus and subse- 

 quently by white ants may in the later 

 stages of disease show no signs of fungus 

 attack owing to the disappearance of the 

 strands of mycelium. Such cases are in- 

 variably diagnosed as being due to white 

 ants only ; and, on the whole it would 

 appear that a large proportion of the 

 damage which is attributed to white ants, 

 more particularly among older trees, is 

 initiated by the root fungus. In young 

 clearings, on the other hand, many trees 

 are attacked by white ants without any 

 intervention on the part of the fungus." 

 It would seem that conditions in Malaya 



