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forms are known, but little attention is paid to them since it seems that the 
asexual spores play no réle in the life-history. Some believe that the 
pycnospores are not even capable of germinating. 
_ The Primary Cycle is initiated by the ascospores which are forcibly 
ejected from the open apothecia on dead needles at any time during the 
growing-season when sufficient moisture is present. 
Pathogenesis. The apothecia are formed on dead needles of 
healthy twigs and witches’-brooms. Although the twigs are penetrated 
and killed by the mycelium, the apothecia are formed only on the needles, 
In the material provided, OBSERVE :— 
6. The longitudinal slit running the length of each apothecium. 
DRAW. 
- 7. That, in material which has been in a moist-chamber, the two 
halves forming the covering of the apothecium are pulled apart exposing 
the hymenium. DRaw. 
In prepared cross-sections of needles with apothecia, NOTE :— 
8. That the apothecium is formed under the epidermis in the 
mesophyl-tissue. 
9. The black mycelial covering of the fruit-body. 
— 10. The asci and paraphyses arising from the base of the fruit- 
ody. 
11. The ascospores; two-celled and much longer than broad. 
DRAW showing the structure of the apothecium and contents. 
On the same needles with the apothecia are the smaller asexual fruit- 
bodies,—the pycnidia. In the material, NoTE:— 
12. The resemblance between the apothecia and pycnidia. 
Crush one of the pycnidia in water. OBSERVE :— 
13. The elongated conidia. The conidia of the leaf-cast patho- 
genes have never been shown to cause infections. 
The ascospores are shot from the asci when sufficient moisture is present 
to open the valves covering the hymenium. If material is available, 
NOTE :— 
14. The milky deposit on the glass slides suspended over the 
discharging apothecia. 
15. By examination with the microscope, that this milky 
deposit is due to the large number of ascospores ejected upon it. 
Saprogenesis. There is no distinct or obligate saprophytic exist- 
ence required in the life-history of this pathogene. Leaves infected in 
early spring are killed and while still attached to the tree produce mature 
_apothecia in the late autumn, although usually they do not mature until 
the following spring or summer. Pycnidia are formed among the apothecia 
at the same time. 
Secondary Cycles are apparently lacking in the case of this pathogene, 
since it takes the fungus a year to develop new inoculum. 
REPORT 
1. Formulate control measures for this disease in a nursery 
which is surrounded by a mixed forest containing yellow pine. Give 
reasons for all steps in proposed measures based on the facts known about 
the life-history of the pathogene. 
