Plant Sanitation. 4 



though these are growing in the midst 

 of dead jak roots covered with the 

 fungus. 



Ustulina zonata, Lev., the common 

 tea root fungus of the low-country and 

 up to an elevation of 3,000 feet, has been 

 found to originate on Albizzia stumps 

 and to spread from them to the tea. 

 It was already known that Grevillea 

 stumps furnished it with a jum ping-off 

 ground in practically all instances of its 

 occurrence, but now Albizzia stumps, in 

 accordance with expectation, must be 

 added. This is a spore-borne disease, 

 and when I was developing Ustulina on 

 tea stumps in pots under bell glasses on 

 the laboratory verandah, I had great 

 difficulty in preventing its growth on 

 other dead tea stumps or coconut tissue, 

 also under bell glasses. In contradistinc- 

 tion to many of our disease fungi, the 

 spores apparently germinate readily, 

 and this fact should enable us to obtain 

 further information about this parasite 

 rather more easily than is usually the 

 case, when time permits, On estates 

 the spores are blown about and lodge 

 on the cut surfaces of the Grevillea 

 stumps ; there they develop and grow 

 downwards, destroying the stump and 

 passing from the Grevillea roots to any 

 tea roots which may be in contact with 

 them. Meanwhile the fructification is 

 formed on the Grevillea stump in black 

 encrusting plates, and the spores which 

 exude from the spore-chambers are 

 ready to carry the disease elsewhere. It 

 is not often that the fructification is 

 formed on the tea bush, because the 

 bush dies and is uprooted before the 

 mycelium has ascended in the stem to 

 the ground level. Ustulina zonata was 

 first found on coconut, but probably 

 only saprophytic. It causes root disease 

 in the Punielo, and in an unnamed tree 

 in the Peradeniya Gardens. Many 

 European mycologists consider that it is 

 identical with Ustulina vulgaris, which 

 is common in Europe but not parasitic ; 

 but in its typical form it seems suffi- 

 ciently distinct. 



In connection with the above, one 

 wonders who is going to be the first to 

 introduce the Trewhella screw jak for 

 uprooting trees. When some of the 

 felled grevilleas do not exceed six inches 

 in diameter, it would be quite as easy to 

 uproot them with this instrument as to 

 fell them and leave the stump as a 

 starting point for Ustulina, Of course 



5 [May, 1909. 



it is a question whether the outlay and 

 the possible extra cost of working for 

 each Grevillea exceed the value of (on 

 the average) six tea bushes and the cost 

 of liming and trenching. There is, too, 

 always the possibility that the Grevillea 

 stump will be rotted by other, harmless, 

 fungi, and possibly the sporting tenden- 

 cies of the Ceylon planter influence him 

 in accepting what is practically an even 

 chance. I notice that the makers of this 

 instrument have gone so far as to put an 

 illustrated advertisement in the " Indian 

 Planters' Chronicle"; possibly Ceylon's 

 turn will come some day. 



The catch phrase, " the bark is the 

 mother of rubber," is again being pressed 

 into service. This is somewhat unfor- 

 tunate, since it leads to the same train 

 of erroneous ideas which gained currency 

 some years ago, and causes supporters 

 of various tapping systems to imagine 

 advantages which are certainly non- 

 existent. It would be more correct, 

 though open to scientific objections, to 

 say that the cambium is the mother of 

 rubber, just as it is of wood and bark, 



Some time ago, Betel plants were 

 imported from India by the Agricultural 

 Society. Some of these, planted in the 

 Stock Garden, soon became diseased, and 

 were forwarded to Peradeniya for 

 examination. As they were rooted 

 cuttings, carefully packed, and in the 

 early stages of disease, it was possible to 

 form a more accurate opinion of the 

 cause than is the case from the bundle 

 of half-rotten stems which is usually 

 sent. The leaves were covered with 

 blackish-brown, oi almost black, angular 

 spots, with a broad yellow margin and 

 an outer greenish yellow zone. Some of 

 these spots were three centimetres in 

 diameter. The upper surface of the 

 spots was dry, but the lower surface was 

 viscid, being covered with a gummy 

 substance containing innumerable bac- 

 teria. A cross section through the leaf 

 revealed the same bacteria within the 

 tissues, but no fungus hyphaj. It is 

 most probable, therefore, that the 

 disease of the Betel which attacks the 

 leaves and stem is due to bacteria, 

 though of course there may be more 

 than one such disease. Pressure of 

 other work has prevented any further 

 investigation ; the subject is (unfortun- 

 ately !) not forgotten, but remains 

 in that evei -expanding limbo entitled 



