Prickly Pear Menace in Eastern Australia 1880-1940

Prickly pear cactus, introduced into eastern Australia by early settlers, became a major pest in the early twentieth century and caused abandonment of large tracts of rural land. Governmental strategies to halt the pest were ineffectual; some helped the cactus to spread. The discovery in the mid-1920s that the larvae of the Cactoblastis cactorum destroyed the pest was attributable more to luck than to cohesive policy. THE campaign waged from 1880 to 1940 by Australian governmental officials, scientists, and private landowners against the spread of prickly pear cacti throughout Queensland and New South Wales has been called "one of the world's most spectacular achievements in the history of economic entomology" (Johnston and Lloyd 1982, 216). The sheer speed with which the prickly pear invaded farming and grazing lands, the huge area it devastated, and its seeming invulnerability to conventional means of eradication had indeed presented a fearsome challenge. Scientific experts of the early twentieth century were all but at a loss for a solution (Steele 1923, 6). In the face of a looming, apparently irreversible ecological disaster, the sudden termination of the rampage by the prickly pear through inland eastern Australia appears nothing short of miraculous. Government-sponsored researchers grappling with the crisis had realized quickly the extent to which geography was involved in both the problem and its potential solution. Both spread and eradication of the pest had global as well as regional ramifications and involved a combination of environmental, economic, and technological considerations. Recognition of this fact led the small band of scientists desperately searching for solutions eventually to vanquish the pest. In retrospect, however, the assertion by a 1923 royal commission that a definite policy had been "consistently followed by successive governments" to combat the spread of prickly pear (Steele 1923, 4) and the notion that the spectacular elimination of pear infestation was a direct result of carefully planned and consistent governmental action are highly debatable. During most of the period in which prickly pear emerged as a grave threat to Australian rural development, governmental policies unwittingly promoted the spread of the pest rather than arrested it. When the mistakes were recognized, almost at the eleventh hour, the federal and state governments * I thank Colin Sheehan, principal librarian, for permission to reproduce materials from the collection of the John Oxley Library, Brisbane. The maps were drawn by Carol Randall and Caroline King of York University. * DR. FREEMAN is an associate professor of geography at York University, North York, Ontario, Canada M3J 1P3. This content downloaded from 157.55.39.35 on Wed, 31 Aug 2016 04:25:04 UTC All use subject to http://about.jstor.org/terms THE GEOGRAPHICAL REVIEW adopted suggestions for improved policies halfheartedly, without much hope for or expectation of any appreciable success. The governments appeared almost completely resigned to abandoning an enormous area of rural land overrun by the prickly pear. Their often lukewarm support for research and their hesitant, cost-conscious stance on direct action to deal with the problem threatened to undermine the efforts of the few researchers who had dedicated their skills and energies to resolving the crisis. GEOGRAPHY OF A PESTILENCE Prickly pear is the common name for several species of the genus Opuntia (family Cactaceae) that are indigenous to the western hemisphere. All are hardy, drought-resistant, subtropical perennials comprising a profusion of fleshy, flattened, segmented stems studded with tufts of spines and covered with fine, nettlelike cilia. Some, like the common pest pear Opuntia inermis, which is native to the Greater Antilles and the coast of the Gulf of Mexico, and 0. stricta, which is from Chile, grow in massive thickets between onehalf and two and one-half meters high, but others, such as 0. streptacantha and 0. tomentosa, both native to central Mexico, are tree pears reaching heights of eight meters or more. Depending on the species, they may be propagated very rapidly by seeds or by broken stem segments, which are transported by animals, strong winds, and floodwaters. In their native environments, these cacti have rarely been accorded the status of agricultural pests; however, introduced into other parts of the world, notably Australia, Hawaii, India, Sri Lanka, Madagascar, and southern Africa, they have quickly gained notoriety as noxious weeds. In Australia, the prickly pear turned into a land-greedy menace that ruined many farmers and ranchers and threatened the rural economy of an entire continent. Coastal and interior areas of eastern Australia proved to have climatic and edaphic characteristics very well suited to several species of prickly pear. The early, rapid dissemination of prickly pear species was a direct result of misguided experiments by European immigrants who had deliberately carried the plant and established it in areas of new settlement. Thereafter, very rapid diffusion of prickly pear was aided by accidental cartage by humans, consumption and dissemination by domestic animals and native fauna, and transport by wind and water. Like many environmental disasters, the prickly pear problem began with good intentions. The plants initially arrived in Australia on the ships of the first fleet bringing European convicts and soldiers. Cuttings were taken on board at Rio de Janeiro on an impulse by the first governor, who believed, wrongly, that the plant might become the basis for a flourishing cochineal dye industry (Johnston and Tryon 1914, 127). Several different varieties of the prickly pear imported by later immigrants proved useful as a cheap, effective hedge plant that bore edible fruit. Scattered specimens of 0. inermis, which became the main pest species, were taken from Camden, near Sydney, to Scone in mid-northern New South Wales in 1839 (Fig. 1). Cuttings from 414 This content downloaded from 157.55.39.35 on Wed, 31 Aug 2016 04:25:04 UTC All use subject to http://about.jstor.org/terms