New Yokk Agkicultueal Experiment Station. 175 



tMs may not have been wliolly due to the powdery mildew. The 

 plans were affected to a considerable extent also by downy mildew, 

 Plasmopara cuhensis (B. & C.) Humph. 



Since no perithecia Avere found the identity of the fungus is a 

 matter of conjecture. On his mildewed greenhouse cucumbers 

 Humphrey found the perithecia of Erysiphe ciclioracearu'm D. C. 

 According to Frank^ Sphaerotheca castagnei Lev. occurs on 

 cucumbers in Europe, but the most common powdery mildew of 

 cucumbers and other cucurbits in Europe is known only in the 

 conidial form which passes under the name of Oidium erysiphoides 

 Fr. Sturgis^" assumes that the powdery mildew of the cucumber 

 is identical with \\m one occurring on squash, but to us this appears 

 extremely doubtful for the following reasons: The powdery mil- 

 dew is common in this country on squash but on cucumber it is 

 rare. During the past two seasons it has been abundant on both 

 squashes and pumpkins in the vicinity of Geneva, but in no case 

 have we observed it upon cucumbers, although cucumber vines 

 have frequently been seen growing among mildewed squashes and 

 pumpkins. Vice versa, on Mr. Estabrook's farm at Athens, Pa., 

 a squash vine running among the mildewed cucumbers was entirely 

 free from mildew. 



Cucumber growers need not be alarmed at the appearance of 

 this new parasite. It is not likely to become epidemic and in case 

 it should do so it will probably not be found difficult to control. 



III. DODDER ON CUCUMBERS UNDER GLASS. 



The numerous species of dodder, Gusciita, may be expected to 

 occur on a gi*eat variety of plants in the open air, but it is unusual 

 for them to attack greenhouse plants. An interesting case of dod- 

 der occurred in the Station cucumber-house last spring. In May, 

 the writer observed a slender, yellow dodder thread twining about 



9 Frank, A. B. Die Krankheiten der Pflanzen. 2 : 260. Eduard Trewendt, 

 Breslaii, 189G. 



lOSturgis, W. C. Twenty-First Ann. Kept. Conn. Agr. Exp. Sta., 1897: 214. 



