gg Wheat Rust in Australia. 



The Australian rust has been determined as Puccinia gramas by 

 Eriksson and other authorities; but if the ability to produce the aecidmm 

 >n the barberrv is taken as the final criterion, then judgment must be 

 suspended in 'numerous other cases. Thus Massee * has found P. 

 wmiis on Alopecurus pratensis, and Avena elatior in the Royal Gardens 

 ut he significantly adds-- Notwithstanding the great quantity of 

 Jfcrfefii and Mahonia present in the grounds, the most careful and con- 

 tim, , has failed to reveal the presence of the aecidiospore stage. 



" 7, P- 7 



THE PROBLEM STATED. 



In dealing with the rust question from a practical point of view, there 

 were two main issues to be determined: 



i How is the rust spread and continued from season to season? 

 2*. How may its injurious effects be mitigated or counteracted or 

 prevented ? 



The first question is a most important one, for if we could find out 

 where and under what conditions, the rust is lying dormant during the 

 time from reaping the crop to sowing it again, then we might be able 

 destrov it at this stage, and prevent its reappearance. Although the 

 question may thus be simply stated, it is by no means easy to answer. 



The second subject of prevention or mitigation will evidently depend 

 on our knowledge of the life-history of the rust fungus, as well as of the 

 wheat plant itself, and how far the conditions can be controlled which 

 render it susceptible to the fungus. 



How the Rust is Spread and Continued from Year to Year. We 

 know exactly now, thanks to the labours of Eriksson, Marshall 

 Ward, and others, how the, rust-spores enter the plant by means of their 

 germ-tulbes, how they grow and ramify among the tissues, and drain them 

 of their contents, until they again form a spore-layer, and reproduce the 

 spores on the surface in great abundance. We thus know how fresh 

 spores orginate once they have got a start; but it is the starting-point 

 which is the difficulty. 



Although the rust was known, and the effects produced by it were 

 familiar from remote antiquity, yet its true nature was not discovered 

 until the latter half of the eighteenth century. As late as 1733, Jethro 

 Tull, writing about it in his Horse-hoeing Husbandry, attributes it to the 

 attacks of small insects " brought, some think, by the East wind, which 

 feed upon the wheat, leaving their excreta as black spots upon the straw, 

 as is shown by the microscope." In 1767, its true nature as a fungus, and 

 therefore as a plant, was determined by Felice Fontana, and in 1797, 

 Persoon gave it the name by which it is still known, Puccinia graminis. 

 The rust then is a fungus growing inside the wheat-plant, and living at 

 its expense, and reproducing itself by means of minute seed-like bodies 

 or spores, which are so conspicuous on the leaves and stem of the wheat 

 at certain seasons. 



For a long time there was a suspicion in the minds of many practical 

 farmers that the barberry bush- had something to do with its spread', and 

 so firmly was this believed in, that the State of Massachusetts passed an Act 

 compelling the inhabitants to extirpate barberry bushes. And when De 

 Bary, in 1864, justified the farmer, and proved scientifically that there 

 was a connexion between the fungus which appears on the barberry 

 bush, and that which appears on the wheat, then it was thought by 

 many that we had reached the root of the matter, and that we had simply 

 to destroy the barberry bush in order to get rid of the rust But it is well 





