Plant Sanitation^ 



294 



[May 1907. 



attacks camphor and Panax They differ from the other tea root diseases in that 

 their mycelium is to a great extent external- One of our species covers the root with 

 black strands ; the other forms a loose coating which is at first white and afterwards 

 smoky grey or black. When the mycelium penetrates the bark it spreads out in 

 the shape of stars over the wood. With a microscope there is never any difficulty 

 in determining Roseliinia mycelium as it shows peculiar characteristic swellings on 

 the hyphae. 



The difficulty oi obtaining the ascospore fructification (perithecia), either 

 in cultivation or in the field, has been repeatedly referred to. These are small black 

 spherical bodies about one-twelf fch of an inch in diameter, and they usually grow in 

 clusters. I have one specimen, presumably on tea, and others on Panax, but in each 

 case there is some doubt whether they, were connected with the mycelium on the 

 roots. Neither of these is Roseliinia radiciperda, Mass., and this species has most 

 probably not occurred in Ceylon. These fructifications can only be produced above 

 ground, and are most likely to be found at the base of the stem. 



But another fact in the life history of Roseliinia has been completely 

 overlooked in dealing with the Ceylon disease. As soon as, often before, the bush is 

 dead, another form of spore is produced in myriads on the stem. The lower part of 

 the stem, sometimes to a height of a foot, is covered with a black velvety coat of 

 close-set erect hyphae which bear innumerable spores at their extremities. When 

 these spores are produced the surface is grey with them. I have had tea stems 

 attacked by Roseliinia under cultivation for more than a year, and during the 

 whole time there has been a constant succession of crops of these spores. It is 

 probable that these serve for the propagation of the fungus under ordinary con- 

 ditions, and that the ascospores — which are resting spores enabling the fungus to 

 survive unfavourable conditions — are rarely produced. It follows that it is a waste 

 of time to trench round diseased areas without at the same time burning the dead 

 and dying bushes ; and these should be burnt on the spot, if possible, as carrying 

 them about the estate will inevitably spread the spores. Most of the cases of 

 Roseliinia sent in are in this spore-bearing stage. 



In dealing with the Roseliinia on Panax, it was found that the mycelium 

 spread on the surface of the soil among the dead leaves at the base of the hedge, 

 and it was impossible to stop it until these had been raked away. In most cases 

 the disease originates on Grevillea stumps and spreads underground. Roseliinia is 

 apparently not known in lowcountry districts, but may be found in all others. 



Preventive Measures. 



When a bush is attacked by root disease, there is practically no hope of 

 saving it. All measures must be directed to preventing the spread of the fungus to 

 neighbouring bushes. As the mycelium spreads under ground, and usually within 

 the first foot of the soil, trenches about eighteen inches deep must be dug round the 

 dying bushes in order to isolate them. It is better to include within the area 

 enclosed by the trench a ring of the surrounding apparently healthy bushes, since it is 

 most probable that the mycelium will already have advanced underground as far as 

 these. The dead bushes within this area must be dug out and burned ; this is 

 especially necessary in the case of Roseliinia, because the spores of the fungus are 

 always produced as soon as the bush is dead and are soon blown away. Carrying 

 the bushes about the estate should be avoided as far as possible. When this must 

 be done with Roseliinia affected bushes, the stem should be scorched, by burning 

 some material at the base or by applying a torch before, the bushes are dug up. The 

 ground from which the bushes have been removed should be forked over with 

 quicklime and left exposed for a year. 



