19 



Dr. Thurston, as his report indicates, made 

 no personal inv^igations, but submitted the 

 question to the Collectors of the Several districts 

 of the Presidency for consideration. Amongst 

 . the replies that he publishes, the following may 

 be mentioned: — 



The Collector at Cuddapah reported that 

 spots of a rusty colour appear on the green plant 

 and increase in size. They may cover the whole 

 plant and destroy it. 



The Collector at Chingleput submitted a letter 

 from Lieutenant-Colonel W. G. King, in which 

 the following statement occurs: — " In the course 

 of my inquiry as to the existence of Cochineal 

 Insects I ascertained that considerable destruc- 

 tion of Prickly-pear had occurred in a village 

 south of Samiapagunta (of Ponneri taluk), on 

 the border of the Pulicat Lake, which my in- 

 formant believed might be the Cochineal In- 

 sect." . , . The Tahsildar of Chingelput sent a 

 special messenger for specimens for Dr. King; 

 and the latter states that he " confirmed what I 

 had heard as to the destruction proceeding in 

 this neighbourhood, and brought me a speci- 

 men." Dr. King then submitted this to a 

 " Madras expert " . . . " who, however (as Dr. 

 King states), could only state that it was a name- 

 less mycelial growth." Evidently the specimen 

 was in an advanced state of decay when he re- 

 ceived it, for it is stated that " the whole sub- 

 stance of the plant underwent a process of de- 

 composition by liquefaction."* 



The Collector (W. J. H. le Fanu) at Salem 

 forwarded the following observations made by 

 some of his subordinate officers : — 



1. " The occurrence of an orange-coloured 



disc-shaped fungus attacking the 

 Prickly-pear," and " such parts of the 

 plant as are attacked by it are eventu- 

 ally partially or entirely killed out by 

 it," is reported by S. C. Moss, Extra 

 Assistant Conservator of Forests, 

 Hosur and Dhamapur Ranges. It is 

 further stated that specimens illustrat- 

 ing the occurrence of this fungus were 

 sent to J. S. Gamble, Director of the 

 Imperial Forest School, Dehra Dun, 

 who on examination " expressed doubts 

 as to the discs being an insect. ' 'f - 



2. With regard to Salem also, the District 



Forest Officer reports the existence of 

 an " orange-coloured fungus or para- 

 site, not unlike Coffee Leaf Disease, de- 

 stroying the Prickly-pear. This fungus 

 seems to attack the plant more readily 

 in shady or moist situations. I have 

 seen it very frequently withering away 

 with the said yellow spots, and have in- 

 variably noticed that this was the case 

 when the soil was bad. I do not be- 

 lieve there is any fungoid disease which 

 will damage Prickly-pear in good soil, 

 and generally it is prolific in such soil." 



3. The Head Assistant Collector, again, with 



reference to the same place, reports the 

 existence of " two kinds of disease 

 amongst Prickly-pear." The first he 



• Lieut.-Col. W. G. King, 9th Dec, 1895, Board of 

 Revenue, Madras, No. 2316, 1895. Vid. Mr. Wood's 

 conclusions previously cited, since they relate also to a 

 " disease " of Prickly-pear occurring at Chingelput. 



t Vid. Dr. Thurston's Report, p. 3. 



mentions as presenting the following 

 symptoms: — The plant becomes at first 

 yellow, then brownish spots appear on 

 it extending over the whole plant. 

 When the last stage has been reached, 

 " the pulpy matter becomes dry and 

 brittle and the plant is dried up and 

 destroyed." This is said to be a very 

 common disease, which " eventually de- 

 stroys the Prickly-pear." Of the second 

 he states that when the plant is "af- 

 fected by it, it keeps its green colour, 

 but presents a very dried appearance 

 and looks as if it had no humidity in it. 

 In the course of time white spots appear, 

 and the plant looks as if it were bitten 

 off in places. This disease is said to be 

 rare, and it is not known whether it 

 ultimately destroys the plant." 



These references to Prickly-pear affections, 

 mentioned in 1896 in those reports of several Col- 

 lectors of the Madras Presidency, serve to de- 

 scribe two Prickly-pear maladies, both of which 

 appear to be of a non-parasitic nature and non- 

 communicable. One of these, the second Prickly- 

 pear trouble mentioned by the Head Assistant 

 Collector of the Salem district, appears to corre- 

 spond to one elsewhere described (Tryon, 1908) 

 as " Dry Rot." The other, in which the earlier 

 symptoms are the appearance of ' ' rusty-coloured 

 spots," "yellow spots," "brownish spots," or 

 "an orange-coloured disc-shaped fungus" (?), 

 with more or less chlorosis, is evidently one the 

 subject of official unprinted reports by one of us 

 (H.T.) on Prickly-pear maladies in the West- 

 brook and Nudgee districts of Southern Queens- 

 land, and considered to be due to the immediate 

 action of some locally-produced irritant of a 

 chemical nature acting under permanent or 

 transitory defective soil conditions, and in its 

 origin is not explicable by any parasitic micro- 

 organism — fungus or otherwise — evidence of 

 whose presence is not forthcoming. 



Both of these constitutional derangements 

 were met Avith in the Madras Presidency, the 

 former only occasionally at Bellary and else- 

 where. 



The prolonged investigation necessary for 

 the proper elucidation of the latter disease could 

 not be entered upon in the course of this inquiry, 

 and was, moreover, not a work quite within the 

 scope of the Commission. Some light may, how- 

 ever, be thrown upon it by the following state- 

 ments made in the course of a paper by one of 

 us (Tryon, 1911, p. 7) :— 



The symptoms exhibited at an early period 

 in the history of this Prickly-pear affec- 

 tion are, generally speaking, compatible 

 with the action of some parasitic organ- 

 ism — of a fungus or bacterial nature. 

 However, microscopical investigation 

 fails to bring to light the presence of 

 any such agent. Moreover, when kept 

 under conditions favourable to their 

 growth and manifestation, no micro- 

 fungi capable of acting as parasites are 

 found occurring, much less any one of 

 the several kinds that are know to con- 

 sort with Opiintia as a host plant. 

 The features that are the earliest to be dis- 

 played suggest the action of some toxic 

 fluid, formed within the plant tissue. 



