1(1 Jl-ly, 1917.] Weeds. 427 



Those of you who are unable to enter the maelstrom as depicted, have 

 a duly pointed out. This duty can, T think, be extended to see that not 

 only is the present emergency met, but that the future is provided for, 

 and thai you should at once commence to gather together and form those 

 materials whicli will be so urgently required to reestablish on ccmniercial 

 lines our great and glorous Empire. 



WEEDS.* 



ISi/ II . W . DdVi'ii, F.E.S., Orchard Stiperriitor. 



In writing this paper I do not claim to be an expert on all weeds 

 tliat, unfortunately, tax the man on the land, but I have given a good 

 (leal of consideration to combating certain noxious plants, and have 

 conducted many experiments for their eradication, notably the worst of 

 all our weeds — St. John's Wort'. 



In the following paper, as one who knows the difficulties in dealing 

 with 'certain weeds, I have not recommended treatment that- often is 

 quite impracticable on steep country. In advising the frequent cutting 

 of perennial weeds, which is usually a costly process, it is really the 

 cheaper method to attack the thing properly and eradicate the pest than 

 to make a lot of half-hearted efforts that will never eradicate the trouble, 

 but instead allows the plants year after year to gradually extend their 

 grip on the land, wliile still maintaining their held on what thev have. 



The number of introduced species of plants that rank as w-eeds is 

 becoming greater every year. This is another instance of an introduced 

 species displacing the indigenous. A plant, like an animal, is always 

 more or less subject to natural controls in its native country, and these 

 controls usually are absent when a plant is introduced into new Bur- 

 roundings. This lack of control ofteij allows an alien plant to get 

 completely out of hand unless vigorous steps are taken for its suppression. 

 The same plant in its native country is often a host for numerous 

 enemies in the form of insects or fungi, that either kill it or control 

 its seed production; but in a country like Australia, with its favorable 

 climate and soils, these alien plants find moi-e ideal conditions for their 

 propagation and dissemination. As a result they often spread to an 

 alarming extent. 



Tlie seeds of weed plants may be introduced into a country in many 

 ways, cliief of which may be by dirty seed being imported. Packages 

 and their packing are another source of supply, and ships arriving from 

 foreign countries in sand ballasti — the latter being often used for reclama- 

 tion purposes is a common source for the invasion of noxious plants. 



Once introduced the means by which they are spread over the 

 country are many, among which may be menticned : Stock feeding on 

 the plants and the seed passing through them with their germination 

 unimpaired; birds that eject from the mouth indigestible portions of 

 their food in the form of pellets, such as our magpies, are the principal 



• Taper read at tlio Annual Convention of the Oiianiber of .4griciilture held .it ISendlgo, Jnly, 1917. 



