Plant Sanitation. 



490 



Dec. 190f>. 



unsuitable situation. It was quite certain that the beetle observed only bored 

 into the stem after it was dead. In order to test this conclusion, the treatment 

 which is detailed below was advised, but as far as I could judge when I passed the 

 place some months afterwards nothing has been done. 



Quite recently one of our leading coconut planters (who had raised the 

 question of this disease in 1903) kindly offered to show me other localities in which 

 the disease existed, and under his guidance more valuable information was obtained. 

 In a plantation at Nalla, which was visited, two thousand trees are said to be 

 affected, and though none have yet died, the number of diseased trees is increasing. 

 It was seen that the ideas founded on the observations made previously on the 

 palms near the canal would not hold good there, but fortunately a clue to the 

 origin of the disease has been found in the specimens there collected. The longi- 

 tudinal cracks in the outer tissue are a more or less normal feature of the coconut 

 stem. They are not necessarily connected with disease, though it is probable that 

 fungus enters through them. In the earliest stages of the disease, the sap oozes 

 out from the trunk and causes a brown or black stain on the exterior. If the 

 diseased region is cut into during wet weather a quantity of sap runs out. The 

 tissue beneath the black patch decays, finally becoming dark brown or black. 

 Instances of this appear to be fairly common. There are numbers of old trees 

 on which the disease has been at work for years, doing no more harm than locally 

 destroying the outer tissues, the hard wood below being apparently too dense for 

 it to operate upon. A hole, filled at first with dry fibres, is left in the stem. 



But in the cases which have attracted attention recently, the first black 

 or rusty patch is followed by others, usually on the same side of the tree, and the 

 diseased regions extend internally until the whole trunk is merely a shell 

 enclosing a brown or black soil-like mass. 



There is no doubt that the progress depends on the character of the tree, 

 and older trees appear to be less affected. But tiees of all ages are attacked, and 

 the difference appears to depend on age only in so far as the older tree possesses a 

 well-developed region of dense " wood." The trees which are killed succumb in 

 from four to six years. 



The fungus which is supposed to be the cause of the disease is wholly 

 internal. Its spores are formed in the decaying tissue, and are brought to the 

 exterior by the exuding sap. In order to have the disease under observation, 

 inoculations were made at Peradeniya with diseased tissue, and with the sap 

 containing the spores and some bacteria. But the only trees available at Peradeniya 

 are extremely old, and it is as yet doubtful whether the infection has been suc- 

 cessful. It is only by making pure cultivations of the fungus and inoculating the 

 trees from them that certainty can be arrived at. 



In addition to the Hendalla and Nalle districts, I have seen odd trees 

 affected in the neighbourhood of Kandy. "The disease is fairly prevalent every- 

 where, but so far has not done any serious mischief. It seems to have increased of 

 late in certain localities." " The progress of the disease is slow, taking possibly 

 four to five years to kill the trees, but we think it is sufficiently serious to warrant 

 attention." These are the opinions of our leading coconut planters. 



The following measures were tried several years ago and have proved suc- 

 cessful. All the diseased tissues were cut out and burnt, the wounds were then 

 burned with a torch of rags dipped in oil, and then covered with hot coal 

 tar. All dead coconut trees should be burned. With respect to the last point, 

 the advice recently issued by the American Department of Agriculture in the 

 Philippines may be quoted. ',' The first thing to do in coming into possession of a 

 coconut grove, or in planting a new one, is to thoroughly clean the ground. All 



