OKANGE LEAF RUST OF WHEAT. 41 



conditions and in certain localities, considorablo injury may ensue if 

 the rust occurs mucli in advance of harvest. In all instances, however, 

 where the wheat is a total loss, which often occurs in such States as 

 Kentucky, Indiana, Texas, Michigan, and Ohio, the black stem rust is 

 found to be the chief, if not the only, rust present; and in all the 

 writer's experience he has not met with a single well-authenticated 

 case in this country where the leaf rust caused actual shriveling of the 

 grain.' 



In recent years botanists of all countries except England and Sweden 

 seem to agree that F. ruhi(jo-vera is not only the common rust, which is 

 true, but also the one of economic importance, as will be seen by con- 

 sulting the writings of Arthur (1), Bolley (7, pp. 13, 14), Barclay (5, Vol. 

 XXX, pp. 4G, 47), and Oobb (1<S, p. 34),- and in view of the limited amount 

 of field work done it is natural that such an idea should prevail. The 

 error arises from confusing the abundance of orange leaf rust every 

 year with the destructive effects of black stem rust in certain years. 

 Farmers, however, universally fear "black rust on the stems." It is 

 significant in this connection that Barclay (5, Vol. XXX, p. 47), after 

 admitting that the natives in India recognize the difference between 

 "rolli" (P. graniinis) and "rolla" ( /*. rubU/o-vera), yet says that a 

 "Zemindar" who sent him specimens stated that "rolla " is less destruc- 

 tive than "rolli." 



Farrer (33, p. 30; 33a, pp. 103, 104) has for some time maintained that 

 in Australia P. ruhigo-vera does but little damage. McAlpine (51, pp. 

 27, 28; 52, p. 20) also seems to believe the damage is commonly done by 

 P. graniinis. The writer's experiments at Garrett Park, Md., afforded 

 an excellent opportunity to test the matter thoroughly, P. graniinis 

 being entirely absent there in 1895, while P. ruhigo-vera was about as 

 abundant as it could well be. As shown in Table 3, r majority of the 

 varieties were very much rusted, yet the very sorts rusted most pro- 

 duced perfectly plump grains. On the other hand, curiously enough, 

 it is constantly maintained that wheat is badly damaged by rust in 

 the Southern States and in nearly all cases the orange leaf rust is the 

 one reported to be present. However, the matter should be looked 

 into more carefully in that region. In several cases of complete destruc- 

 tion of the grain personally investigated by the writer in the south- 

 eastern part of Texas, P. graniinis was undoubtedly the real cause. 



' Barclay (5, Vol. XXX, pp. 4, 5) gives two instances in which he weighed the grains 

 of samples of wheat affected with P. rtibitjo-vera received from diftereut phices in 

 India, and found that those of one sample weighed one-sixth as much as correspond- 

 ingly healthy ones and those of the other sample weighed one-half as much. How- 

 ever, nothing is said as to whether the healthy grains were of the same variety of 

 wheat as the injured ones or whether P. (jraminis was not also present on the rusted 

 specimens. 



2 It is admitted by Cobb that P. (/rrtmiw/s perhaps did the damage to wheat in 

 Australia in 1889, and that it may be the iujurious species in some other years, as it 

 is " a very vigorous rust." 



