530 NEW JERSEY AGKICILTL'HAL COLLEGE 



celery Ijlight, both of which germinate with remarkable rapidity in 

 water. When surrounded with their congenial food — that is, an ex- 

 tract of the host plant — the rate over that of pure water is augmented 

 many times. When copper is added to the water the spores fail to 

 germinate, or, in short, the results are the same as those reported 

 for monila. 



"Similar experiments have l)een made with metallic zinc, but even 

 when the spores were literally surrounded by the granulated metal 

 they grew with vigor. A powdered form of metallic zinc was also 

 used, and even in abundance had no retarding- effect." 



For the out-of-door mildews, particulary the Sphcerotlieca mors- 

 'uvoB (Schw.), there have been many trials made with, a long list of 

 substances. At the Xew York (Geneva) Ex}wriment Station this pest 

 has been under treatment for some years. The following is quoted 

 from the Bulletin ]S^o. 161:* For three seasons Bordeaux mixture, 

 lysol and formalin have been compared with potassium sitlphide, the 

 latter giving the best results in all three series. The recommendation 

 is to use potassium sulphide, one ounce to two or three gallons of 

 water, and the spraying shotild begin just as the gooseberry buds 

 are opening and be continued at the usual intervals of ten days. 



It is not unlikely that good results would obtain with the potassium 

 •^sulphide upon garden phloxes or any other of the affected hosts for 

 the powdery mildews. 



In Plate XII., Fig. 1, is shown a lilac leaf with the mildew 

 {Microsphcera Alni) in a young condition upon the upper side. The 

 somewhat circular spots are so many developments from points of 

 inoculation. Over some areas of the leaf the circles of spreading 

 fungous threads have met with others, and a nearly uniform coating 

 will in time result. This is particularly true of the left half of the 

 leaf above the middle, while upon the right is a portion of the leaf 

 with but few mildew patches, and a very ^mall one may 1)e distin- 

 -guished like a star in an tmaffected area of the leaf. 



At '2 is a leaf of the ordinary dooryard plantain, showing, in young 

 .^condition, the very common species Erysiphe Ciclioraceanim DC. as 

 it develops upon the upper side of the leaf. It also illustrates the 

 preierence shown for the veins, as it is seen that the patches center 

 along these lines, possibly because of the greater amotmt of moisture 

 here met with upon the surface. 



* Treatment for Gooseberry Mildew, by C. P. Close, November, 1899. 



