AGRICULTURAL BULLETIN 



OF THE 



5TKAIT5 



AND 



FEDERATED riALAY STATES. 



No. 5.] MAY, 1911. [Vol. X 



THE OCCURRENCE OF BURRS ON THE TRUNK 

 OF HEVEA BRASILIENSIS. 



By Keith Bancroft, b.a., Assistant Mycologist, F.M.S. 



For several years repeated attention has been called to the 

 occurrence of excrescences or burrs on the trunk of Hevea Brasiliensis. 

 These excrescences not only interfere with smooth tapping, but may 

 attain such dimensions as to render the surface untappable and to 

 necessitate the transference of the tapping;' area to the upper parts 

 of the trunk. They were first recorded in the " Tropical Agricultu- 

 ralist " of September, 1905, and have since been discussed by Fetch 

 in Circular No, 18, 19OQ, of the Royal Botanic Gardens, Ceylon. 



Burred trees are commonly met with in the Federated Malay 

 States; the/ occur alike on high and on lowland, on well drained 

 and on badly drained soils. The burrs are referable to two distinct 

 sources and will, therefore, be dealt with separately. Those of the 

 • one type, although apparently stimulated by wounding, occur on 

 untapped as well as on tapped trees and cannot, therefore, be said to 

 be due entirely to any artificial stimulus ; while those of the other 

 .type are distinctly the result of wounding. 



Burrs of the First Type. 



These are far more important than those of the second type. 

 The earliest record of their appearance is on trees of four years of 

 age which had not been tapped ; they are most frequently met with, 

 however, on trees which have passed the age of first tapping, and 

 .they can be seen to best advantage on old trees. 



