87 Plant Sanitation. 



fication of the fungus. All the diseased tissue on one tree was cut away, and the 

 wound healed in a few months. The diseased bark was stripped off the other, but no 

 attempt was made to cut out all the affected parts; indeed, even this treatment was 

 contrary to instructions, as we wished to ascertain what effect the fungus would 

 have on the tree if unchecked. During the ensuing dry weather a healthy callus 

 was formed round the wound, but with a renewal of the rains, the fungus recom- 

 menced active growth and spread in all directions, almost completely destroying all 

 the bark. At the same time, white ants attacked the diseased wood and reduced 

 the tree to a narrow stick about an inch in diameter with a strip of sound bark on 

 one side. 



This fungus has not been found elsewhere on Castilloa, but it attacks and 

 kills young Hevea braailiensis, especially stumps. It has also been found sapro- 

 phytic on dead Hevea. Its effect on young Hevea will be dealt with later. 



A third fungus was found on a specimen submitted for examination a short 

 time ago. The affected trees show an open wound at the collar, extending up the 

 stem in a long triangular patch and at the same time spreading more extensively on 

 the roots. It is similar to the "foot rot" of orange trees, and, like that disease, is 

 caused by a species of Fusarium. The fungus appears through small cracks in the 

 apparently sound bark in the form of white tufts which at first sight may be mis- 

 taken for drops of coagulated latex. Diseases of this class are favoured by bad 

 drainage or excessive shade, anything, in fact, which causes an abundance of 

 moisture at the foot of the tree. In one instance, the affected trees are in an area 

 which cannot be properly drained, and in another, though the drainage is good, the 

 trees have made such remarkable growth that there is probably too much shade. It 

 has been recommended that the measures adopted against "foot rot" in orange 

 trees should be tried in this case, but it is as yet too early to say whether they are 

 successful. The earth is removed from about the tree so as to expose the collar and 

 part of the roots. The diseased tissue is then cut away, and the wood painted with 

 a mixture of crude carbolic acid and water in equal parts. All the wood and bark 

 removed must be burnt. The hole should not be filled up until the tree has 

 recovered, and, if possible, the shade should be thinned out so that the sun may reach 

 the affected parts. 



In other investigations, two interesting results have recently been obtained 

 by cultivations at Peradeniya. The white root rot of tea, which has hitherto been 

 confused with Rosellinia, and which seems never to produce any fructification in the 

 field, has in four cases developed a sporophore which proves it to be a species of 

 Polyporus, one which, judging from a brief visit to Hakgala, jis common in the 

 jungle on dead wood. The other result concerns the " Thread Blight " dealt with in 

 the Tropical Agriculturist for April, 1906 ; this, at least on nutmeg trees at Pera- 

 deniya, is the mycelium of a small stemless agaric (mushroom), a species of 

 Crepidotu8, which is only fully developed on twigs etc. after they have fallen and 

 commenced to decay, 



