116 K'lnsas Academy of Science. 



teleutospores, or the black rust. These carry the fungus 

 through the winter. 



It will be seen that there are two hosts. It follows that if one 

 host, or if any one stage, excepting the spermatia, be disposed 

 of, then the rust will be stopped. It happens that in Kansas 

 there is a negligible quantity of barberry, and yet we' have 

 much rust. It is true that there are other wheat rusts besides 

 Puccirtia graminis, but we have much that is apparently this 

 species. Some other explanation must be had. 



It may help some in understanding the problem to state that 

 presumably only the aecidiospores and the uredospores are 

 capable of infecting the wheat, ^cidiospores are probably 

 only on the barberry, and we do not have the barberry. Ure- 

 dospores are not supposed to withstand the winter, but we still 

 have the rust. What is the answer to these seemingly contra- 

 dictory statements? We shall endeavor to sum up the various 

 theories, and perhaps add some original suggestions or facts 

 having some bearing on the subject. It is an important one, 

 as a loss estimated at one hundred million dollars annually in 

 the world is said to occur from this parasite. 



Strasburger^ thinks that the fungus persists through the 

 winter in the winter wheats. This would have to be infected 

 in the fall, presumably from volunteer wheat, and this in turn 

 from uredospores still retaining their vitality from the har- 

 vested wheat. Coulter- is authority for the statement that 

 uredospores have been known to have lived through the winter 

 and infected the wheat in the spring. He also states that 

 teleutospores have been known to produce basidiospores cap- 

 able of infecting very young wheat plants. Whether these 

 could infect winter wheat plants started the fall before is an 

 open question. Possibly there might be some wheat lying un- 

 germinated in the soil, and that this could furnish the needed 

 young plants. The teleutospores do not germinate until in the 

 spring, it will be remembered. 



We have often suggested to our students that there is some 

 probability that the fungus is conveyed to, or is at least found 

 in, the related perennial grasses near the wheat ; that it there 

 persists through the winter and again produces uredospores 

 capable of infecting the related wheat. This suggestion is 



1. Strasburger, Textbook of Botany, p. 407. 



2. Coulter. Te.xtbook of Botany, vol. 1, p. 85. 



