51 



that the injury is sometimes severe (Tryon, 

 1911 b, p. 16). It is not, however, likely to be of 

 much use in controlling the Australian pest pears. 



Phoma tor r ens, Sacc, has been referred to 

 by Saccardo as an enemy of Cactaceae in the Rome 

 Botanic Gardens, but its effects do not appear 

 to be sufficiently serious to justify its introduction 

 into Australia. 



Certain minor maladies were met with at La 

 Mortola. Amongst them was a " sun scald " 

 affecting 0. bergeriana and other species, 

 especially when grown in exposed situations. 

 The joints were yellowish and spotted with pale 

 rusty-brown markings, which later became larger 

 and greyish, when the perithecia of a fimgus re- 

 lated to Mycoprion were to be observed within 

 the diseased area. As a rule, no further results 

 were brought about, though occasionally the 

 affected segment ceased to produce new growth. 

 The condition resembled one met with on prickly- 

 pears at Gayndah,,, in our own State. 



A few plants showed the presence of pale 

 brown areas with lighter coloured centres, 

 individual spots coalescing to form large dis- 

 coloured patches with a simple wavy outline. 

 Ultimately the superficial tissues may die, when 

 the perithecia of a fungus make their appearance. 

 This malady appears to be unimportant. 



A single specimen of 0. megacanthd, S.D., 

 was found to have some of its segments affected 

 by a malady for which the name " zone spot " 

 may be employed. There were well-defined red- 

 brown concentric areas, which were of a lighter 

 colour at the margin of each ring. These patches 

 may continue to widen and eventually coalesce 

 with other spots, so that discoloured areas several 

 inches across may be produced. The affected 

 epidermis may become grey and flake off, expos- 

 ing brownish scars, but the underlying tissue does 

 not seem to be injured to any degree, so that the 

 malady is not of any importance there.* 



The occurrence of etiolation and chlorosis in 

 Opuntias has been referred to by a few writers 

 such as Meyen, Hallier (1868, p. 100), and 

 Hirscht (1899, p. 796). These affections, which 

 are also met with in Queensland (Tryon, 1911 b, 

 p. 17) do not appear to be the result of parasitic 

 agency. 



Besides these, various other fungi have been 

 recorded by Saccardo, RoUand, and other mycolo- 

 gists, as attacking 0. ficus-indica and other 

 prickly-pears in Southern Europe. 



* F. von Thumen, when dealing with the fungi o£ 

 fruit trees (1887, p. 70) enumerates the following fungi as 

 ocourring on 0. ficus-indica : — 



On the fruit. — Aspergillw africanus, Dur. and Mntg. 



On the stem joints. — Diplodia opuntice, Saoc. ; Nea- 

 tria jucunda, Mntg. ; Phyllosticta opuntiw, Saoo. 

 and Speg. ; SpJiceria cacti, Schweinz. 



On the stem. — Diderma vaccinum, Dur. and Mntg. ; 

 DidymoephcBria opulenta, Dur. ; Leptoaphcena 

 aicula, Saco. and Beltr. ; Mycoprion Ivxtiense, 

 Saoc. ; Perisporium wrightii. Berk, and Curt. ; 

 Phoma cacti, Berk., var. Opuntice, Sacc. ; Pleu- 

 rotua opunticB, Dur. ; Rhytiama cacti, Schwemz ; 

 Sclerotium cactearum, Speg. ; Teichoapora mvere- 

 cunda, Sacc. ; Apoaphceria fbrisegua, Saco. ; and 

 Roadtmia horridula, Sacc. 



DESTRUCTION BY MECHANICAL 



MEANS. 



Of the species occurring wild in the Medi- 

 terranean littoral, only two are really common. 

 Owing to the value of their fruit and joints as 

 food they are widely cultivated, and the question 

 of destruction is not often raised. There are 

 several factors which control to a large extent the 

 spread of Opuntias in this region, one being the 

 relatively large agricultural population engaged 

 in relatively small areas, another being the hot, 

 dry climate which is experienced during a con- 

 siderable part of the year, more particularly in 

 Spain, Southern Italy, Sicily, Northern Africa, 

 Syria, and Palestine. 



When destruction is deemed necessary the 

 plants are cut down by manual labour, allowed 

 to dry for a few days under the influence of the 

 hot sun, and then burnt. Occasionally a trench 

 is dug, the plants are thrown into it, and on 

 decay serve as manure. Even if cut down during 

 the summer and left alone, few of the joints grow 

 again in the Barbary States on account of the dry 

 heat. 



It is worthy of remark that, although the 

 fruits are so much used as food and the seeds thus 

 distributed widely, one very seldom meets with 

 seedling plants. This may be due to a destruc- 

 tion of the germinating power of the seed by the 

 intestinal juices, or to the detrimental effect of 

 the summer climate. 



DESTRUCTION BY UTILISATION. 



Just prior to our leaving Europe for the 

 United States, there was received from Mr. J. 

 C. Briinnich, the Chemist to the Department of 

 Agriculture, Queensland, a tabulated statement 

 of the result of his analyses of specimens of — (1) 

 green plants, (2) air-dried plants, and (3) the 

 fruit of the various kinds of prickly-pear occur- 

 ring in Queensland. This report, which was 

 kindly prepared by him at the request of the 

 Commission, was asked for so that we might be 

 acquainted with the amount of fibre, galactan, 

 sugars, etc., present in our commoner naturalised 

 Opuntias, and therefore in a better position to 

 discuss with those technically interested the 

 possibility of utilising these constituents in the 

 arts or industries. Owing to its value, it is 

 printed in extenso at the end of this section of our 

 report. 



Utilisation as Pood for Man. 

 As 0. ficus-indica and 0. amyclcea are not 

 naturalised in Australia, and more especially since 

 the remarks would not necessarilv annlv to the 

 pest pears there, there is no need to enter exten- 

 sively into the matter of the utilisation of these 

 plants in the Mediterranean zone as articles of 

 food for man. The fruits of both species are 

 esteemed as an article of food by the peoples of 

 the Mediterranean littoral, and since the plants 

 are usually readily grown and yield abundance 

 of fruit during certain seasons, it is not surprising 

 that these Opuntias have a considerable economic 

 value there. In drier regions— e.g., Egvpt. 

 Algeria, and Tunisia, as well as in parts of 

 Morocco and Andalusia, 0. ficus-iiidica is care- 



