40 



intermittent, as the amount of money voted for 

 this purpose was insufficient. Moreover, there 

 appears to have been a considerable amount of 

 waste going on. Prom 1905 the poison was sold 

 at cost price (R.S.C., 1906, p. 2; Nobbs, 1906 

 a, p. 10). 



Dr. Hutcheon, Acting Director of Agricul- 

 ture (R.S.C., 1906, p. 3), stated that it was more 

 effective to dig out the pear, collect it into heaps, 

 and then spray thoroughly, than to inject the 

 poison into the standing plants. Many South 

 African farmers have agreed with this statement 

 (R.S.C., 1906, pp. 52, 57). 



About this time certain local proprietary 

 preparations came to be used. The most satis- 

 factory was that of a Mr. Pienaar (R.S.C., 1906, 

 pp. 13, 29, 36). This poison was patented, its 

 composition being given (p. 60) as copper sul- 

 phate, 14 oz. ; sodium hydroxide, 20 oz. ; water, 

 160 oz. Two solutions were made separately and 

 then mixed together. A tablespoonful of the 

 liquid was placed in a hole bored into the stem 

 and main branches at a distance of three joints 

 from the end (p. 61), and the hole was then 

 plugged up. Soon the pear began to die from 

 the tips downwards (p. 13), the joints remaining 

 ou the plant if proper care were taken during 

 the injection. This was found by Dr. Nobbs to 

 be effective and to be more easily applied where 

 plants were sparse (p. 13). The objection to 

 the use of this preparation was its costliness (6s. 

 per gallon plus cost of railage), though it was 

 stated that the ingredients cost about Is. per 

 gallon at Capetown. On the other hand, this 

 remedy was tried by the Municipality of Uiten- 

 hage, which cleared portions of its densely in- 

 fested town common of 5,000 " trees " at a cost 

 of £4 (p. 67) and 8,675 at a cost of £26 8s. (p. 

 35). This works out at a cost of about ^d. and 

 %d. per tree, respectively. All the expenses can- 

 not have been included, since a later account 

 given by Dr. Nobbs (1906 a, p. 29) refers to 

 the destruction of 18,989 trees at a total cost of 

 £119 18s., the work thus costing the municipality 

 about ll^d. per tree. In a Departmental report 

 (October, 1906) Dr. Nobbs stated that over 

 25,000 trees had been destroyed at a total cost 

 (for labour, material, and cost of supervision) 

 of £168 13s., which still works out at about li^d. 

 per tree. The plants were said to average 8 feet 

 in height. So successful was this remedy deemed 

 to be that the Uitenhage Council proposed (p. 

 36) to spend £200 per annum in clearing its com- 

 monage with the preparation. Though success- 

 ful at all seasons, its action was found to be more 

 rapid during summer (p. 63), decomposition set- 

 ting m about a fortnight after injection. In 

 winter time this occurs in about three weeks. 



Exhaustive experiments were carried out 

 during 1906 and 1907 by Dr. Nobljs (1907) He 

 used samples of eighteen preparations then in 



use, each being used — (1) as a spray on heaps 

 of pear which had been grubbed out; (2) as an 

 injection into standing trees; (3) as an injection 

 into stumps ; and (4) as a spray against standing 

 trees. The substances tried were arsenite of 

 soda, proprietary preparations (Steyn's, Pie- 

 naar 's. Cairns', Duplessis', Mares, Atlas), Coo- 

 per's Dip, common salt, blue vitriol, green 

 vitriol, arsenate of lead, potassium cyanide, sul- 

 phur, caustic soda, and paraffin. As regards 

 efficiency, arsenite of soda proved itself to be the 

 best and cheapest cacticide. 



The most efficient and economical method of 

 using this poison (Nobbs, 1907, b, p. 4) was to 

 f eU the trees, spray the heaps with 1 -1 per cent, 

 solution (1 lb. arsenite to 9 gallons water), and 

 then inject about 1 to 1^ tablespoonfuls of a 

 10 per cent, arsenite solution into the butts of 

 the stumps projecting above the ground. Spray- 

 ing standing trees with a 5 per cent, solution of 

 arsenite of soda is " recommended for use in 

 checking the progress of the Prickly-pear on 

 steep hillsides " and other places " where more 

 thorough work is impracticable, but where ex- 

 tirpation is very desirable," since these act as 

 redistributing centres for the pest. The main 

 objection is the difficulty of water supply in these 

 spots. 



The success following a demonstration of 

 the efficacy of a proprietary compound made by 

 Mr. Jansen (Edit., 1909) led the Government to 

 purchase the secret of its composition. It was 

 made as follows : — 



1. Boil thoroughly for 30 minutes half a 



pound of good finely powdered lime and 

 half a pound sulphur in one gallon of 

 water. An extra quart of water should 

 be added to above to allow for evapora- 

 tion whilst boiling. 



2. Dissolve half a pound of salt and half a 



pound of arsenite of soda in one gaUou 

 boiling water. 



3. Mix the above Nos. 1 and 2 together, 



which will then equal two gallons fluid 

 stuff. 



4. To be applied as the tree stands, as fol- 



lows: — Make an incision with a knife, 

 with a sharp point, two to three inches 

 deep into one or more leaves, according 

 to size of tree, and inject the poison. 



The number of incisions necessary for a 

 tree can soon be gained after a short 

 experience with the extirpator. For 

 instance, if a tree of medium size eon- 

 tain one stem with no branches, one in- 

 jection at the top of the tree will be 

 sufficient to destroy the whole tree. 

 Thus it only needs a little foresight to 

 enable the work to be done with tlie 

 least expense. 



