Volume VIII AUGUST, 1921 No. 2 



ON THE SUPPOSED OCCUPvRENCE OF SEEDLING 

 INFECTION OF WHEAT BY MEANS OF RUSTED 



GRAINS 



By W. L. WATERHOUSE, B.Sc, Agr., 



Waller and Eliza Hall Research Fellow of the University of Sydiiei/. 



{Department of Plant Physiology and Pathology, Imperial College 



of Science and Technology.) 



An important paper by Hungerford has recently appeared in the Jour. 

 Ag. Research, vol. xix. 15 June, 1920, p. 257, deahng with "Rust in 

 Seed Wheat in Relation to SeedUng Infection." As the result of careful 

 and exhaustive experiments he states that, contrary to results reported 

 by a number of previous workers, "stemrust {Puccinia graminis tritici, 

 E. and H.) is not transmitted from one wheat crop to the next by means 

 of infected seed grain. Further, in the writer's judgment, the occurrence 

 of stemrust sori in the pericarp of the caryopses of grains and grasses 

 has no especial significance, but the infection spreads to these tissues 

 just as it does from an infection point in any of the vegetative parts of 

 the plant" (p. 275). 



The same writer gives a comprehensive summary of past work on 

 this question and a full bibliography. 



The present investigation was undertaken to see whether a histo- 

 logical examination of rusted grains during germination and the early 

 stages of growth would throw any light on the problem. The results 

 obtained confirm Hungerford's work and are briefly reported here. 



In April, 1920, grain was obtained from a crop of wheat which was 

 grown in Pembrokeshire in 1919 and badly rusted. Stubble left in the 

 field was frequently found black with teleutosori, which were also abun- 

 dant on awns, chaff and fragments of the rachis found mixed with the 

 grain. The presence of teleutosori at the hilum end of a number of grains 

 was determined and these grains were picked out. Several counts showed 

 the percentage of rusted grain in the sample to vary from about 0-5 to 

 1-0 per cent, of the whole. The percentage of abnormal grains of a scabby 

 nature was higher than this, and spores of the Fusarium and Helmin- 

 thosporium type were obtained in scrapings from some of these. 



Ann. Biol, vin 6 



