33 8 The Botanical Gazette. [December, 



Notes upon Peronosporese for 1891. 



BYRON D. HALSTED. 



The season now closing has been an average one as to the 

 total amount of rainfall, but the two previous years were mod- 

 erately wet ones, and particularly 1889. Of special note in 

 this connection is the amount of rain that fell during the month 

 of August, namely, 5.32 inches on an average throughout the 

 state; while the September precipitation was not so great but 

 near the average. 



Phytopiithoka INFESTANS D. By. While not one quarter 

 as prevalent as last year this rot has not been absent, espe- 



cially among the late potatoes. 



J 



about ten days after a series of rains. The writer is more than 

 ever convinced that much of the decay of Irish potatoes in the 

 East is due to bacteria and the Phytophthora gets credit for 

 much more damage than is its due. 



SCLEROSPORA GRAMINICOLA (Sacc.) Schr. which is common 

 upon Sctaria viridis and S. Italica in Iowa, has not yet been 

 found in New Jersey. The first host for this mildew gives one 

 of the best illustrations of how the sustaining tissue breaks up 

 into fine shreds as if to facilitate the dispersion of the oospores 

 as it doubtless does. 



Plasmopara vitjcola (B. & C.) Ber. & De T. was com- 

 paratively rare upon the grape during the early part of the 

 year, but after the crop was removed the mildew showed itself 

 upon the mature leaves in remarkable abundance. So rapid 

 and great was its growth in September that the vineyardists 

 frequently mentioned the fact of their own accord. This 

 seems to be a striking example of the mildew being associated 

 with the moist weather of the autumn. It has been again 

 observed that the lower leaves, that is, those nearest the soil. 

 are the most certain to be attacked, leaves lying upon the 

 earth being worst of all. It has not been as abundant upon 

 Ampclopsis quinquefolia and A. tricuspidata as last year. 



Plasmopara pygm.ka (Ung.) Schrcet. was found in small 

 quantity in early spring upon Anemone nemorosa but not met 

 with upon its other hosts. 



Plasmopara Gera.mi (Peck) Berl. was in early spring one 



of our most abundant and conspicuous members of the group, 

 as upon Geramum Carolinianum it covered the leaves with a 



