144 IOWA ACADEMY OF SCIENCES. 



P. Graminis Pers. 



Not common on Triticum vulgare, Avena sativa and 

 Hordeum jubatum. June and July. Aecidium abun- 

 dant on Berberis vulgaris May-June. Very destruc- 

 tive on fall sown oats and wheat. August and Septem- 

 ber; also Hordeum jubatum. 

 P. coronata Cor da. 



Not common on Avena sativa, June and July. Abundant 

 August and September. Kiebabn has recently sepa- 

 rated another species out of what has passed as this, 

 until further work in this country, the species is used 

 here as it is by American authors generally. 

 P. rvbigo-vera (D. C.) Wint. 



Not common, on wheat June and July. Abundant on fall 

 sown wheat, Hordeum jubatum, August and September, 

 Squirrel-tail grass is held in check by this fungus. 

 P. Sorglii Schw. 



Abundant August and September on Zea Mays. 

 P. emaculata Schw. 



Abundant on Panicum capillare August and September. 

 P. Andropogonis Schw. 



Not abundant on Andropogon furcatus. A. scoparius, 

 August and September. 

 P. Xaiifhii Schw. 



Abundant on Xanthium Canadense, July, August and Sep- 

 tember. In low grounds destroyed a large number of 

 plants. 



PERONOSPORACE^. 



Cystojyys candidvs (Pers.). Lev. 



Abundant early in the season on Lepidium intermedium, 

 L. Virginicum, Capsella bursa-pastoris. Later, oos- 

 pores abundant in infloresence of Rhaphanus sativa. 

 C. Tragopogonis (Pers.) Schroet. 



Locally abundant in June and early July. 

 a Portulacce (D. C.) Lev. 



Abundant on Portulaca oleracea from the middle of June 

 to the first of September. Oospores abundant. 

 C. Bliti (Biv.) De By. 



Abundant July, August and September on Amarantus albus, 

 A. retroflexus. More severe on the latter species. 

 Sderospora graminicola (Sacc.) Schroet. 



Abundant during the latter part of May till middle of June, 



