Mar. 2, 1920.] Agricultural Gazette of S.S.W. 166 



A Note on the Over-summering of Wheat 



Rust in Australia. 



W. L. WATERHOUSE. B.Se. (Agr.), 

 Walter and Eliza Hall Agriculture Research Fellow, University of Sydney. 



The question how nist of wheat survives through the hot Australian summer 

 and successfully infects the next year's crop is of the utmost importance, 

 and the answer should be found if the disease is to be satisfactorily dealt 

 with. Various solutions of the problem have been offered. In his " Rusts 

 of Australia," p. 69, Mc Alpine suggests that the self-sown or '" volunteer " 

 wheat growing in the paddocks or on headlands may be responsible rather 

 than the black oats and other grasses. 



In the course of some work at Sydney University dealing with the rust 

 ))roblera, an effort was niade to secure evidence bearing on the point. 

 Thanks to the courtesy of Mr. G. Valder, Under Secretary, for Agriculture, 

 and his officers, visits were paid to certain of the Government experiment 

 farms where wheat is an important crop, and from time to tim,e observations 

 were made in the field. The period that was covered extended from June, 

 1918, till March, 1919. The summer of 1918-1919 was one of the driest 

 recorded in the parts visited; drought conditions were general and no rust 

 epidemic was reported anywhere in the State. 



It should be remembered that the destructive rust of the wheat crop in 

 Australia is the Summer Rust or Black Stem Rust (Puccinia (jrammis). A 

 second form, known as the Spring Rust (Pmcinia trificuia), occurs, but it 

 is usually stated that this does little damage. The Yellow Stripe Rust 

 {Puccinia glumarum), which does so much harm in Europe, has not yet been 

 reported from Australia. 



In June, 1918, abundance of self-sown (from shed grain) and second-growth 

 wheat was found in heavily stocked stubble paddocks, gTowing in the shelter 

 of thistles and other coarse plants, in crops of rape, on headlands under 

 fences, and more especially round haystacks. It Avas also present in 

 quantity along some of the railway tracks. On the leaves, stems and ears 

 of this volunteer wheat a large amount of summer rust in the uredo and 

 teleuto stage was found, as well as the uiedo stage of the spring rust. 

 Uredospores were tested and proved viable. At this time the gi-owing 

 crop was about 6 inches high, and in many places was only a few yards 

 away from the badly-infected volunteer wheat. On this sown crop, how- 

 ever, no sign of summer rust was discovered, although pustules of the 

 spring rust were plentiful on the seedling leaA^es. 



