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11. The much coarser and more densely matted mycelium; 
not pure white but yellowish or brownish. 
12. The globose perithecia of varying sizes and colors enmeshed 
in the mycelial mat. 
SKETCH to show the appearance under the binocular microscope. 
Saprogenesis. The perithecia usually begin to appear while the 
leaf is still green, but do not mature their ascospores until the leaves 
die and are overwintered. The perithecia on the dead leaves on the ground 
pass the winter in an inactive condition. The rains and warm weather of 
spring cause the asci to mature their ascospores. 
To simulate the spring conditions, some of the leaves bearing immature 
perithecia have been placed in warm water for several days. They are 
now mature. 
Remove some of the perithecia to a slide in water and cover with a cover- 
glass. Crush by pressing firmly on the cover with the handle of a scalpel, 
while watching the perithecia under low-power. What comes out of the 
perithecium? How many? What is the character of their contents? 
Does the perithecium have an ostiolum? 
DRAW to show a perithecium with its contents. Show the structure of 
the perithecial wall and mycelial attachment. 
With the maturity and discharge of the ascospores, the secondary 
cycles are completed. 
REPORT 
1. Explain the significance of biologic strains in E. graminis 
DC., with respect to control. 
2. Discuss eradication measures in the control of powdery 
mildews. 
