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26. With the sclerotia of Sclerotinia Libertiana as to size, color 
and relation to substratum. Make comparative SKETCHES. 
Crush or section one.of the minute sclerotia of B. paeoniae and OBSERVE :— 
27. Its structure: the outer black rind-cells and the central white 
medulla. pDRaw: 
The diseased shoots shrivel and fall to the ground, harboring the 
sclerotia until next season. The mycelium frequently spreads down from 
the diseased shoots into the crowns and roots causing root-rot. 
It appears probable that mycelium as such and not in the form of 
sclerotia, hibernates in the old tissues and even spreads through them as a 
saprophyte giving rise in the spring to conidia for the primary infections. 
Examine the old stems in the moist-chamber. They have just recently 
been brought in from the field. OBSERVE :— 
28. The numerous tufts of brown conidiophores covered with 
the grey conidia. From what do the conidiophore-clusters arise? Dis- 
sect one of them carefully away from the stem. Do they ever appear to 
arise from a sclerotium? 
Secondary Cycles. The conidia produced on the diseased young 
shoots are carried chiefly by ants to the developing buds where in the 
sugary exudate they quickly germinate, penetrate and cause the bud- 
blast. 
Other secondary cycles are exhibited later in the bud-rot, blossom-rot, 
upper stem-rot, and leaf-blight. The fungous structures produced; 
their relation to, and effects upon the tissues are the same as those of the 
primary cycles. Sclerotia are rarely produced, however, in any of the host- 
organs other than the stem. The mycelium of the secondary cycles in 
old leaves and especially stems gives rise in the moist days of spring to 
great numbers of conidia which may also initiate primary cycles. 
REPORT 
1. Write a letter to a peony-grower in reply to the query “How 
shall I proceed to control the Botrytis blight in my peonies?”’ It is to be 
assumed that the correspondent knows the various symptoms of the 
disease and that it is caused by a fungus. 
