Wheat Rust in Australia. 67 



known elsewhere to carry the aecidial stage of P. graminis. In one case 

 the infected branch was placed under a bell-jar to preserve moist conditions, 

 but there was no result with any of the species, since the weather was too 

 hot and dry. 



In 1902, in order to give the experiment another trial under the most 

 favorable conditions, Dr. Plowright kindly forwarded several young bar- 

 berry bushes from England, which arrived here in December in good con- 

 dition. Rusted straw was specially kept exposed to the weather in order to 

 inoculate the barberries. About i6th September the barberries were 

 putting forth their young leaves, and looked very healthy. One was kept 

 as a check, and the others were infected, either by scattering rusted straw 

 around the plants and tying it on to them, or, in two cases, by applying 

 germinating spores direct to the leaves. Some plants were kept under 

 bell-jars, others exposed, and all were attended to and watered freely. The 

 result was that not the slightest trace of any fungus appeared on any of the 

 barberry leaves. It may be stated that the conditions for fungus growth 

 were most favorable, as at times that muggy heat prevailed, which so 

 quickly spreads the rust in a growing crop. 



In 1904 the experiments were continued in the pots, partly on the same 

 lines with rusted straw, and partly by planting a rusty wheat beside the 

 barberry, so that it might be naturally infecfed next season. 



Cuttings from the English barberries have also been planted at Port 

 Fairy in a rusty spot where they have thriven, and Queen's Jubilee 

 wheat planted around them produced abundance of P. graminis. The 

 rusted straw was allowed to die down on the spot, and every 

 facility given for the inoculation of the barberry, but without 

 result so far. Some P. graminis on wheat was sent by Dr. 

 Plowright in March, 1903,' which was gathered In September, 

 1902, and kept in his garden till March. On arrival here 

 some of it was kept inside, and a portion placed outside exposed to the 

 weather, just as was done with Australian rusted straw. It was thus 

 exposed during our winter months of June, July, and August, and in 

 September it was tested, being then exactly twelve months old. While the 

 teleutospores about six months old from the Australian wheat germinated 

 freely, there was no change in the spores from the English wheat, and 

 although attempts were made at different times, there was never any 

 sign of germination. Probably they were kept too long, as they might 

 have germinated on or about the English spring. Prior to this, I had sent 

 rusty Australian straw for trial to Dr. Plowright, but none of the teleuto- 

 spores showed the slightest trace of germination. Writing in the Gardeners' 

 Chronicle for i5th January, 1898, he says 6 : "I have tried on two 

 occasions to get the teleutospore of Puccinia graminis from Australia 

 to germinate in England, but I have not succeeded. The first attempt was 

 made nine years ago, when Mr. D. McAlpine was good enough to send 

 me material ; but I was quite unsuccessful. Last year he was kind enough 

 to send me a further supply ; but, although I kept the straw out of doors 

 during the latter part of last winter and the spring of 1897, I was equally 

 unsuccessful. Is it probably like the seeds of some of the higher vege- 

 tables, the teleutospores require not only a period of rest, but also an 

 exposure to a certain degree of cold?" Seeing that the spores germinated 

 freely here, the "exposure to cold " theory does not hold ; and the most 

 probable explanation is that they had been kept too long, and attempts 

 to germinate them should Rave been made in the English autumn. As 

 far as Australia is concerned, the rust which does the principal damage 

 has apparently no intermediate, stage. 



