GRASSES OF IOWA. 209 



described by Fuckel.* The only extended economic account 

 was made by Trelease, + in 1886 There are also shorter 

 accounts by the writer. J; This fungus is especially common 

 on orchard grass. It is reported as destructive on timothy 

 and oats by Eriksson. § It also occurs on timothy and at times 

 is quite destructive. It produces what is sometimes called 

 rust. The writer has also found it on barley. Tubeuf || reports 

 it on oats It has, however, never been noticed on this host in 

 Iowa. Trelease,t describing the occurrence of the fungus 

 about Madison, Wis., says: "When the basal leaves of orchard 

 grass had reached their full length, my attention was attracted 

 by a very abundant discoloration of this species, sometimes 

 confined to the extremity of the leaves, sometimes extending 

 nearly to their base. So far as my observations went, nearly 

 every stool of orchard grass was affected." 



The first indication of the fungus is an elongated brown or 

 purplish-brown spot. In older specimens the centers of these 

 spots are gray or whitish and contain minute black dots. These 

 small dark spots contain the tufts of brown fungus threads, 

 which make their way out through the stomata. These fruit- 

 ing hyx^hae bear small, smoky-brown, two-celled spores. The 

 fungus causes the cells of the leaf to become much altered, 

 because the colorless threads of the fungus permeate them. 

 The hyphae are sometimes septate and the spores are usually 

 borne at the end or occasioally in a lateral position. On bar- 

 ley the disease is marked by brown or purplish-brown spots 

 which appear on the laaf transversely. Trelease notes that 

 the season of 1886 was a very dry one, very little rain having 

 fallen for several months. 



YELLOW LEAF DISEASE OF BARLEY. 



The yellow leaf disease {Helminthosporium graminum, Rabh) 

 is one of the most destructive of the parasitic diseases affecting 

 barley in Iowa. The fungus has been known for a considerable 

 length of time in Europe, where it was first described by 



*Symb. 107. Saccordo. Syll. Fung. 4: 348. 



+Beal. Grasses of North Am. 1:438. 



+U. S. Dept. Agrl. Rep. 1886: 129. 



JPammel: Fungus Diseases of Iowa Forage Plants. 



tPammel: New Fungus Diseases In Iowa. Jour. Myc. 7: 96. 



§Bidrag till kannedomen om vara odlade vaxters sjukdomar. 185. pi. 9. 



iSorauer. Just. Bot. Jahresb. 1885; 502. 



III. C. Pflanzenkrankhelten. 526. 



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