Plant Sanitation, 



324 



[April, 1910. 



of the kind from Ceylon. The insects 

 frequent outhouses, hiding amongst the 

 rafters during the daytime and sallying 

 out to feed at night. 



The Colombo Lake Fly. 

 I have at last received the scientific 

 name of the notorious ' Lake Fly.' It 

 can now be definitely labelled as Chirono- 

 mus ceylanicus. I fear, however, that 

 this knowledge will not appreciably 

 mitigate the inconvenience occasioned 

 by the pest. 



WILT DISEASE OF PEPPER, 



(Summarised by T. Petch.) 

 The wilt disease of pepper first began 

 to attract attention in Southern India 

 about ten years ago. During the next 

 four or five years it caused considerable 

 loss both on European and native plant- 

 ations, and consequently was the subject 

 of investigation, first by Barber and 

 afterwards by Butler. According to 

 butler's repoit, "over! four thousand 

 acres of pepper cultivation are in the 

 hands of Europeans in South Wynaad, 

 and perhaps five times as many are 

 grown by natives. A far greater 

 amount is grown on the coast districts 

 of Malabar, but it is impossible to esti- 

 mate how much this may be." By 1904 

 some estates had already lost the 

 greater part of their plants, and others 

 were affected more or less severely. 

 About the same time, a disease with the 

 same symptoms was discovered in Java 

 where it was investigated by Zimmer- 

 mann and Breda de Haan. 



This disease was discovered in Ceylon 

 in 1906, and was recorded in the Report 

 of the Mycologist for that year. Since 

 then, specimens have been received from 

 time to time, but no widespread damage 

 has been recorded. Pepper in Ceylon, 

 although a paying crop in some districts, 

 is only a subsidiary one, and there are 

 no extensive areas under pepper culti- 

 vation only. It is usually grown among 

 cacao or tea, and under these circum- 

 stances it is probable that the spread of 

 the disease is restricted. There are 

 small blocks of pepper alone on some 

 estates, and these suffer more from the 

 disease than the vines scattered through 

 cacao. 



The symptoms are described by Butler 

 as follows :— " In a healthy full-grown 

 vine the trunk of the standard is entirely 

 hidden in a mass of foliage. This arises 

 from a number of climbing stems which 

 closely embrace the standard and secure 

 themselves to it by numerous tufts of 

 serial lateral roots. When such a vine 



becomes diseased, the first symptom 

 noticed is an appearance which was 

 described to me as a ' staring ' look 

 about the vine. This is due to a loss of 

 rigidity in the leaves and leaf stalks, 

 resulting in their drooping. W'ith the 

 collapse of the leaves the dense cover- 

 ing of foliage becomes diminished, and 

 the stalks of the vine and patches of 

 the trunk of the standard come into 

 view. The next noticeable thing is that 

 a portion of the climbing stems fall 

 away from the standard, as a result of 

 the death of the clinging roots and 

 consequent relaxation of their grip, 

 Soon the leaves begin to turn yellow, 

 and numbers of them are shed- Later 

 all the vine withers, and the standard 

 remains lightly festooned with dead 

 relaxed stalks beaming a few dried 

 leaves. While the upper part of tho 

 vine makes no attempt at recovery, the 

 lower part often retain sufficient vital- 

 ity to form new leaves, or even to 

 throw out fresh shoots. But these in 

 turn succumb, and I have not come 

 across any case of recovery once the 

 leaf-dropping has commenced." 



The cause of the disease has not yet 

 been fully determined. In Java, it was 

 attributed to the common eel worm, 

 Heterodera radicicola, which was not 

 however thought to kill the vines direct- 

 ly, but to weaken the root system and 

 cause galls through which other organ- 

 isms could enter the plant. This eel- 

 worm is quite common, and it is not 

 surprising that it should occur in the 

 mounds which are built up round the 

 base of the vine in Southern India. But 

 it is not invariably found associated 

 with dead and dying vines, and there- 

 fore it cannot be regarded as the caitse 

 of the disease in all cases, if in any. If 

 the disease were caused by eel worms, 

 the injection of carbon disulphide into 

 the soil would probably be an effective 

 remedy. 



When the vine is dead, the minute red 

 fructifications of a Necttia may some- 

 times be found on the bark, Butler 

 found Nectria in large numbers on dead 

 vines in the Wynaad, but as no descrip- 

 tion has been published, it is doubtful 

 whether the Indian form is identical 

 with that found in Ceylon. A mycelium, 

 presumably that of the Nectria referred 

 to, is found in the vessels of dying vines. 

 Butler regards this NectHa as the cause 

 of the disease, death resulting from the 

 obstruction of the water supply by the 

 mycelium in the vessels and the gum- 

 formation which its presence induces, 



An experimental pepper farm has been 

 opened in Malabar tor the study of 

 different varieties of pepper and for the 



