eN 
Vijfde infectieproef. 
Den Aden Februari 1914 werden 10 infecties met 10 contrôle's ver- 
richt. Dank zij het seizoen slaagden de infecties alle 10, dus 100 °/,, de 
contrôle's bleven vrij van infectie. 
Zesde infectieproef. 
Den 7den Januari 1916 werden 6 infecties verricht, waarvan 5 slaagden 
dus 80°/,. Een daarvan is afgebeeld op plaat 1. 
Streepjeskanker. In de tweede plaats behoeft de bewering nader bewijs, 
dat de streepjeskanker een uiting van kanker is, dus eene ziekteverschijnsel 
veroorzaakt door Phytophthora Faberi MAUBL. 
Streepjeskanker komt zoowel op Ceylon als in de Maleische Staten voor, 
maar wordt daar niet als zoodanig herkend, zooals uit de volgende citaten blijkt: 
PercH schrijft in 1911: *) 
„During the prolonged rains of 1909 and 1910 the renewing bark on 
„the tapped surfaces decayed in many cases. The decay was first indi- 
„cated by the appearance of vertical black lines just above the tapping cut. 
„When the bark was cut out it was found that these lines extended into 
„the wood, and that they were present on the cambium before they were 
„visible externally. The bark along these lines rotted, and left long, narrow 
„wounds extending down to the wood. In some cases the decay travelled 
„downward and involved the untapped bark also. When the rains ceased 
„the decay stopped and the wounds healed up, but the renewal was, of 
„course, rough with vertical swollen ridges of wound tissue. 
„This decay does not appear to be due to “canker”. The colour of 
„the diseased bark differs, and the decay ceases when fine weather sets in. 
„Latex can be obtained from the affected tapping cuts, as there are 
„Strips of sound bark between the black lines. lt does not therefore seem 
„advisable to stop tapping when this occurs, unless it can be shown that 
„it is due to some organism which can be conveyed from tree to tree by the 
„tapping knife. Up to the present all attempts to reproduce this decay by 
„means of the organisms found in the decayed bark have failed, and it 
„seems probable that it is due only to an excess of moisture on the layers 
„exposed during tapping. It is scarcely worth while to excise these black 
„patches, because the amount of injury caused by excision is greater than 
„that caused by the decay of the bark”. 
BANCROFT schrijft, eveneens in 1911: %) 
„Both of these fungi (Nectria diversispora and Stilbella He- 
„veae) have been found associated with an effect on the tapping surface, 
„which at first appeared to be pathological, but which on further investi- 
„gation was found to be only temporary. 
„This effect has been recorded here and there in isolated cases on 
„several plantations, and on one plantation it was present in some abundance 
1) T. PETCH. Physiology and Diseases of Hevea brasiliensis. London 1911, blz. 204. 
2) KEITH BANCROFT. A note on the canker of Hevea brasiliensis. Agric. Bull. 
of the S. S. and F.M.S. X 1911, blz. 203—208. 
