Parasitic Attack on " Eucalyptus Globulus." 857 



Pending a thorongli investigation of other plantations, and 

 correlation of all the evidence as to local conditions, etc., it is difficult 

 to assign the canse of the attack at Cliffendale with confidence. The 

 most obvious thing is to ascribe the outbreak to lack of vigour of the 

 trees due to unsuitable local conditions of soil, or climate, or both 

 these factors, and if so the reason for immunity of living tissue at 

 The Willows where these conditions differ only slightly from Cliffen- 

 dale is not clear. On the other hand, at Lions Glen, where the local 

 conditions approach those of the natural habitat of the blue gum more 

 than at either of the other two places there is at least a suspicion 

 that living tissue may shortly be attacked. Possibly the explana- 

 tion may be found in differences of strain of the fungus, a supposition 

 that can only be verified by introducing the fungus from one place to 

 another or by experiments in the laboratory. 



Recommendations. 



Meanwhile it is advisable to take such steps as suggest them- 

 selves at our present stage of knowledge to prevent loss of a serious 

 character. 



In its saprophytic form the fungus is, of course, harmless to 

 living trees, even though the outer dead bark is attacked. As there 

 is no way of detecting the difference between this and the parasitic 

 form until living tissue is actually attacked, it is advisable to watch 

 blue gum plantations carefully and take the earliest possible steps to 

 destroy the fungus as soon as it first appears. If the trouble is 

 allowed to attain extensive proportions destruction of the fungus 

 becomes too costly to be practical. 



As far as is known, the mycelium does not spread in the soil but 

 in any form of woody debris including twigs and roots, all of which 

 must be destroyed round the infected spot. Experience at Cliff'endale 

 shows that mere charring of the outside of the stumps is insufficient 

 to destroy the fungus as the mycelium inside remains unaffected and 

 soon develops fresh fructifications. The whole stump and root system 

 must be consumed by fire, and the following method is recommended 

 for this purpose : — 



For large trees bore a hole 18 inches deep and 1 inch to 2 inches 

 diameter vertically into the infected stump, put in 1 to 2 

 ounces of saltpetre, fill with water and plug up. After a 

 month or two put a little kerosene oil in the hole and set it 

 alight when the stump will smoulder away to every part of 

 its roots. For smaller trees, holes |-incli to f-inch diameter 

 will suffice, and | to 1 ounce of saltpetre. 



The debris should at the same time be placed round the stump 

 and burned. The above plan is, of course, only practical on a limited 

 scale. 



Spraying with " winter spray," as applied at The Willows, or 

 painting the stumps with some disinfectant, such as carbolineum or 

 tar, which was tried at Cliffendale, is no more effective than charring 

 the outside of the stumps. 



When infection has reached a stage beyond which the above 

 method of destruction becomes impracticable, the only remedy is to 

 convert an infected plantation of E. gJohlulus to an immune species 

 naturally adapted to local conditions. In the case of Cliffendale the 

 best species would be E. rostrata. 



