190 journal of Agriculture. [10 March, 1910. 



Harvesting takes place by cutting and burning off the spines, tiie stock 

 being allowed free access to the plantation and eating the plants as they 

 are prepared for them. A plantation once established will keep good 

 for 15 to 20 years. Harvesting should take place every two years. The 

 fodder cannot be stored and it does not pay to cart it any distance. 



For a dairv cow 140 lbs. per day are needed, for a steer, 75 lbs., i.e., 

 an average of about 23 tons per year. Under cultivation a yield of 

 23 tons per acre can be obtained per annum, but less than 3 tons without 

 cultivation, the plant really being a slowly growing one. 



The plant suffers from three diseases, two of them being apparenth 

 serious ones. Where the grasses are not grazed, it grows less than on 

 grazed land. 



Six pounds of Prickly Pear are stated to be equivalent to one pound of 

 Sorghum hay, so that the proportion to Lucerne might be as 10 : i. 

 Hence, with a moderate yield of Lucerne of, say, 5 tons per acre per 

 annum, the food values per acre are I^ucerne, 50 ; Prickly Pear, 23 ; and 

 this is comparing an average yield of Lucerne with a maximum yield of 

 Prickly Pear. 



To conclude, Prickly Pear will onlv grow in arid districts when it is 

 irrigated, i.e., in districts with an annual rainfall below 16 inches, although 

 irregular stunted growth may of course be possible near this limit. 

 Granted the conditions of rainfall, soil and temperature under which it 

 thrives, better fodder plants can be grown. 



It is one thing tO' endeavour to make use of a plant which has taken 

 possession of the land, but quite another to recommend its cultivation and 

 spread. Where used as a fodder bv burning off the spines, it should be 

 employed only with other more nutritious foods. It is too bulky to 

 transport and too sapp\- to be worth drying or preserving. 



Dr. Griffiths expressly states that it is to be regarded only as 

 " roughage," as a stand by, or as supplementary to other feeds, and the 

 question at once arises as to whether it is not far better and more profitable 

 to store fodder in ricks and silos, rather than allow it to stand in the fields 

 in the form of prickly plants like Spinv Cacti. Remember, that a dairy- 

 man with a hundred cows, in addition to the daily milking, would, if using 

 Prickly Cactus as food, have to cut and burn the s|)ines off more than 

 six tons of the plant -per day! 



With the foregoing facts before them, farmers can conclude for them- 

 selves whether or not the plant is worthy of cultivation. 



ANSWERS TO CORRESPONDENTS. 



Pkunini: Citrus Trees. — C.C. inquires wliether citrus trees require pruning. He 

 also asks whafc amount of manure is recommended. 



Ansiver. — (1) Citrus trees recjuire regular pruning and thinning out, so as tO' 

 relieve them of old and unnecessary wood, to admit light and air. to prevent over- 

 crowding, and to allow the deyelopment of new wood upon which the fruit is borne. 

 This work is very often neglected, and the trees, as a result, present the appearance 

 described. The trees should be pruned and thinned out in spring, cutting out crowd- 

 ing, useless wood, and all old laterals that have carried fruit. Cutoff also all dead and 

 decaying wood. Kemove u])right growths from the centre of the tree, and allow it to 

 spread as much as possible. Examine the roots and stem of the tree for root or collar 

 rot. If either be present, cut away and destroy every trace of diseased wood or bark. 

 Paint the wound with an antise))tic solution of equal parts of carbolic acid and water. 

 The soil should be thoroughly drained, and the roots sliould never be injured by any 

 cultivating implement, i'l) Fi'om 1 lb. to 2 lbs. of sul]ih!itp of iron is a useful manure 

 for citrus trees. 



