108 Wisconsin Academy of Sciences, Arts and Letters. 



PERONOSPOREAE. 



4. Cystopus candidus (P.). 



Common, through the open season, on various crucifers, — Capella 

 bursa pastoris Moench, Sisymbrium officinale Scop., etc. Madison, 

 Syene; Kirkland, La Crosse, Pammel. 



5. Cystopus cubicus (Strauss). 



Oa Ambrosia artemisiaefolia L., Cnicus lanceolaius Hoffm. and Arte- 

 misia biennis Willd. Madison; La Crosse, Pammel. 



6. Cystopus bliti Biv. (C. amaranthi, S.). 



On Amarantus retroflexus L. Syene, Madison; La Crosse, Pammel. 



7. Cystopus portulacae (D C). 



On Portulaca oleracea L. Madison; La Crosse, Pammel; Sauk City, 

 Liiders. 



8. Phytophthora infestans (Mont.) {Peronospora infestans, Mont.). 



Common, in wet summers, on Solanum tuberosum L. Madison; and 

 received from many parts of the state. 

 In some years the loss from the potato rot is estimated at many thous- 

 ands of dollars in "Wisconsin. 



9. Peronospora viticola (B. & C). 



On various cultivated and wild grapes, and on Ampelopsis quinque- 

 folia Micbx. Madison, Syene, Ithaca; La Crosse, Devil's Lake, 

 Pammel; also reported from every part of the state. 

 This certainly causes very much of the dry rot of grapes, as pointed out 

 by Prillieux (Comptes Eendus, Oct. 2, 1882), who has more recently suc- 

 ceeded in observing the germination of the oospores by the direct emission 

 of a mycelial thread, without the intervention of zjosports. I have col- 

 lected it once producing conidiophores on the fruit. 



10. Peronospora halstedii Farlow. 



On Bidens frondosa L., Ambrosia artemisiaefolia L., A. trijida L., 

 Eupatorium ageratoides L., Mudbeckia laciniata L., Silphium 

 terebinthinaceumlu., S. integrifolium,'M.^., S. trifoliatum L., S. 

 perfoliatum L., Helianthus strumosus L., H. occidentalis Ridd., 

 H. tuberosus L. and Solidago riddellii Frank. Madison; La Cross", 

 Pammel. 



11. Peronospora obducens Schr. 



On cotyledons and young leaves of Impatiens fulva Nutt. Madison; 

 La Crosse, Pammel. Also found on Impatiens pallidi Nutt., at Ho- 

 kah, Minn., by Mr. Pammel. 



