41 



The method of injection is as follows: — The 

 leaf which is selected for the injection 

 is pierced with the sharp-pointed knife 

 at the top side of *the apex, and the 

 knife is then moved backwards and for- 

 wards to enlarge the incision. The 

 knife is given a half-twist to open the 

 incision made, and to keep it open a 

 pebble is dropped into the opening. A 

 little of the extirpator is then poured 

 from a kettle into the opening, care be- 

 ing taken, however, to keep the fluid 

 well stirred before pouring it out. The 

 poison travels down the stem, inoculat- 

 ing the leaves as it passes. In doing 

 large dense patches the outside fringe 

 must first be treated, and as these die 

 down the work is repeated on the next 

 fringe, and so on till the centre is also 

 treated. 



This preparation is not meant to be sprayed, 

 and can only be used as per instruc- 

 tions. (Edit., 1910 a, b). 



Another proprietary poison — a spray — has 

 been experimented with (Edit., 1910 c) — ^viz., 

 that of a Mr. St. 'Gorman. Though appar- 

 ently an efficient one, its cost seems to be an 

 objection. 



Still more recently, a Mr. Rademeyer has 

 patented a mixture which, though intended to be 

 used as a spray chiefly against the Jointed Cac- 

 tus, is claimed to be a destroyer of Prickly-pear 

 also. The Commission visited the small experi- 

 mental areas where it had been used two months 

 previously. The plants were not completely de- 

 stroyed, as they were then putting forth new 

 growth. Mr. Rademeyer stated that injuring the 

 plants before spraying was beneficial. He is 

 now engaged in clearing infested land by con- 

 tract. 



The Municipality of Graaff Reinet lets out 

 to farmers for a period of 25 years, free of rent, 

 portions of the town cominon, for grazing pur- 

 poses, on condition that the land be cleared and 

 kept clear of Prickly-pear. 



Dbstkuction of Jointed Cactus. 



From what has already been stated in this 

 section of the Report regarding 0. aurantiaca, 

 known as the Jointed Cactus {0. pusilla) in 

 South Africa, it will be recognised that this 

 species may become a very serious pest. Such 

 has occurred in certain districts in Cape Colony, 

 and may happen in Queensland unless the 

 infested area in the Roma district be thoroughly 

 cleansed. 



The Uitenhage Municipality has for many 

 years been persistently fighting this pest as well 

 as the Prickly-pear, £200 per annum being ex- 

 pended in these directions under the control of 

 Mr. J. Butler. The method at first adopted was 

 to spray the standing plants with a solution of 

 4 per cent, arsenite of soda (Nobbs, R.S.C., 1906, 

 p. 33; Nobbs, 1908, p. 343) ; but at the time of 

 the Commission's visit the plants wore dug out, 

 eoUectPd into a heap, and then sprayed, the mass 

 being burnt when dry. This latter method had 

 already been used against the pest by some 



farmers in the Bedford district (R.S.C., 1906, 

 p. 44, 47; Bowker, 1907, p. 343). The enclosing 

 of infected areas to keep out cattle is a means 

 to prevent the spread of the cactus. 



Experiments were carried out by Dr. Nobbs 

 and Mr. R. W. Thornton during 1907, the results 

 being published in 1908 (Nobbs, 1908). Arsenite 

 of soda, as well as the proprietary preparations 

 claimed to be efficacious against the Prickly-pear, 

 were tried, the first-named being found to be the 

 cheapest and most effective, a 4 per cent, or 5 

 per cent, solution being the most satis- 

 factory. No material advantage was gained 

 by breaking the cactus down before spraying. 

 The results thus corroborated those obtained at 

 Uitenhage by Mr. Butler. 



Just prior to the Commission's visit to South 

 Africa, the Department of Agriculture had in- 

 stituted experiments in order to test the value 

 of a preparation made by Mr. P. M. Rademeyer 

 as compared with arsenite of soda. Agricultural 

 Assistant K. M. Johnson carried out the work at 

 Hankey, and reported that " Rademeyer 's exter- 

 minator " destroyed Jointed Cactus more effec- 

 tively and more cheaply than a 5 per cent, 

 solution of arsenite of soda. The Commission 

 visited the treated areas, but did not find any per- 

 ceptible difference between them, as in both places 

 many plants were sprouting vigorously. There 

 is great difficulty in destroying the "bulb" of 

 this Opuntia. 



The information obtained regarding the 

 destruction of Prickly-pear by chemical and 

 mechanical means, indicates that the most satis- 

 factory and economical results have been obtained 

 by using arsenite of soda solution or "Jansen's 

 Extirpator," these poisons being supplied to 

 farmers at cost price by the Government.* 



SUMMARY OP SOUTH AFRICAN 

 INVESTIGATIONS. 



There appear to be seven or eight species 

 of Prickly-pear naturalised in South Africa, two 

 of which, 0. decumana and 0. aurantiaca, have 

 become a pest in certain areas. The former is 

 represented by two varieties — a smooth-jointed 

 and a spiny-jointed form — -the latter being the 

 troublesome one. 0. monacantha, though widely 

 distributed, occurs scattered chiefly around the 

 coastal area. 



0. monacantha, 0. aurantiaca, and an ally of 

 0. decumana occur naturalised in Queensland. 



No evidence was forthcoming as to the pre- 

 sence of any fungoid or bacterial disease con- 

 trolling the spread of any of these South African 

 Opuntias. A variety of the Wild Cochineal In- 

 sect, Coccus confusus capensis, was found to 

 attack and, at times, seriously injure 0. mona- 

 cantha ; but as far as the experience of the Com- 

 mission went, the general effect produced was not 

 nearly so marked as that seen in India and Cey- 

 lon as the result of the attack of an allied form, 

 C. confusus indicus. This may be due, in part 

 at least, to the presence of parasites. It is known, 



* Under the title " The Prickly-pear Problem, Clearing 

 by Gas," thore appears in the South African Agricultural 

 Journal, 1914, pp. 392-5, a reprint of an article in the 

 Queenslander, giving an account of Mr. Koberts' experi- 

 ments with arsenious chloride as a cactioide. 



