February, 1910.] 



123 



Plant Sanitation. 



I have never heard of a frugivorous 

 snake. It must be of a species quite new 

 to science. All known snakes are carni- 

 vorous. Possibly an explanation of the 

 statement may be found in the fact that 

 rats are fond of passion fruit, and that 

 many snakes have a partiality for rats, 



Ornamental Ribbon-grass, in Colombo, 

 has been attacked by a species of ' army- 

 worm ' (Leucania exempta). It this pest 

 should give serious trouble, it may be 

 checked by laying down poisoned baits, 

 or by the use of Vaporite. 



The caterpillar of Lenodora vittata 

 has been found feeding upon the 

 foliage of sugar-cane in the Peradeniya 

 Gardens. 



An attempt has been made to prepare 

 Kerosene Emulsion by the new formula, 

 in which the oil is emulsified with 

 Bordeaux Mixture instead of with 

 soap. This is the formula evolved at 

 the Woburn Experimental Fruit Farm. 

 The mixture was not successful, owing 

 to the poor quality of the local Kero- 

 sene. In the Woburn experiments, Solar 

 Distillate was employed. 



MISCELLANEA: CHIEFLY 

 PATHOLOGICAL. 



By T. Petch, b.a., b.sc. 



As has beeu announced in the local 

 press that Tea seed imported into,Ceylon 

 from India must now undergo a process 

 of disinfection unless it is certified to be 

 the product of a district which is not 

 infected with "Blister Blight." This 

 disease has been known to occur in 

 Northern India for many years, but 

 since 1906 it has become increasingly 

 jerious, and, according to private advices, 

 it is extending its range. Despite asser- 

 tions to the contrary, it has never been 

 recorded for Ceylon : and it is im- 

 probable that a disease which is dis- 

 tinguished " by the completeness of the 

 destruction which it causes during the 

 short time which it lasts " would have 

 escaped the notice of tea planters. 

 Under these circumstances it was con- 

 sidered advisable to take steps to pre- 

 vent its introduction into the country. 

 This is more especially necessary at the 

 present time, since large quantities of 

 seed are now being imported for exten- 

 sions in tea planting. The disease in its 

 most characteristic form causes raised 

 white circular blisters on the under 

 surface of the leaf ; corresponding with 

 the white blister on the under surface, 

 there is a bright green circular pit on 

 the upper surface. Sometimes these 



conditions are reversed. The white 

 surface, when seen through alense, has a 

 floury or mealy appearance, due to the 

 spores which are formed on it. It has 

 been stated that the fungus (Exobasidium 

 vexans) which causes the disease has 

 been found also on the garden Croton 

 (Uodiaeum variegatum) and on the " Na " 

 tree (Mesuaferrea), but f rom my cological 

 considerations this is improbable. As 

 with the similar reports of the occurrence 

 of Grey Blight on jungle trees in Ceylon, 

 these statements are based only on a 

 superficial resemblance of the leaf spots 

 and not on an examination of the fungi 

 which cause them. The disease is spread 

 by the spores, which are blown off the 

 blisters by the wind ; it is highly prob- 

 able, therefore, that the tea seeds from 

 an infected estate would have some 

 spores adhering to them. We do not 

 know, however, how long the spores 

 retain their power of germination, and, 

 of course, no experiments in this direc- 

 tion are possible in Ceylon. The dis- 

 infection of seeds in order to prevent 

 the introduction of fungus diseases is 

 not a new idea, though it has never been 

 previously attempted in Ceylon ; in the 

 West Indies, cotton seed is always dis- 

 infected with this object. As is well 

 known, many countries have gone 

 further than this, and have prohibited 

 the importation of any seeds or plants 

 from Ceylon, while others have confined 

 their prohibition to particular products, 

 in order to prevent the introduction of 

 Hemileia, Thielaviopsis, etc. 



The destruction of Ceylon coffee by 

 Hemileia vastatrix led to its total 

 abandonment in the Island. Other 

 countries, profiting no doubt by Ceylon 

 experience, have been able, by adopting 

 different methods of cultivation, to 

 retain this . product in spite of the 

 attacks of leaf disease. In some of these 

 countries the search for species which 

 are immune or resistant to Hemileia has 

 been consistently pursued for many 

 years, without any striking success. 

 Java at one time thought that the 

 desired species has been found in Coffea 

 rubusta, but further experience has not 

 justified that idea. Dr. F. C, von Faber, 

 writing in the Tropenflanzer, states 

 "Coffea robusta has been especially 

 cultivated in Java, and does not appear 

 to be very resistant to Hemileia. This 

 plant is comparatively weak, and there- 

 fore suffers more than Liberian coffee 

 when it is attacked. At Buitenzorg, 

 this species is regularly attacked by 

 Hemileia. The great expectations which 

 were based on Robusta coffee do not 

 appear to have been altogether realised,' 



