FUNGI AFFECTING THE SPINACH 



The Spinach Mildew 



Peronospora effusa 



Spinach, when forced for market under glass, is 

 subject to attack by several fungous diseases, which have 



been investigated by Dr. B. D. 

 Halsted. The mildew is one of 

 the most destructive of these mal- 

 adies. It is closely related to the 

 downy mildew of the potato, and 

 produces ^^gray, slightly violet, 

 jDatches of a velvety texture, upon 

 the under side of the leaves, while 

 from the upper side they liave a 

 pale yellow shade, due to the loss 

 of the green color. If a cross 

 section of the leaf be made through 

 one of these i3atches, and a minute 

 piece placed under the microscope 

 on a glass slide, the fungus will 

 be seen to have a structure similar 

 to Fig. 75, which represents on 

 the lower part the cells of the leaf 

 having the mycelium of the fun- 

 gus running between some of 

 them, sending here and there 

 '^suckers" into the cells them- 

 selves to absorb their contents, 

 and pushing out through the 



FIG 75. SPINACH MILDirw. , . •^• 



Section of leaf showino- mvceli- breathmg pore, a, the truitmg 



Zg^;i^^r~"^^'^""' stalk, 5, which bears the spores, c. 

 At d one of the spores is shown, more magnified. These 

 spores are scattered to other plants, where they germinate 



