- ERGOT OF RYE 
This disease is one of the earliest known and most frequently studied of 
ascomycetous diseases of cereals; due doubtless to the poisonous effects 
of the sclerotia of the pathogene on man and beast, rather than to the 
reduction of crop-yields which it causes. The host of greatest economic 
importance is rye. 
SYMPTOMS 
The heads alone show the disease which is exhibited chiefly by the 
presence of the pathogene structures. In the early stages, the pathogene 
produces a honeydew which exudes and runs down over the young spikelets. 
Examine the dried specimens labeled ‘‘ honeydew-stage,” and photograph 
1, fig. 2, 4 and 22, and photograph 9. OBSERVE :— 
1. Smudgy traces of the now dried honeydew. This honeydew 
is often difficult to see in dried specimens but in fresh specimens it is often. 
very copious and sticky. 
Carefully dissect away the glumes in the smudgy region. OBSERVE:— 
2. The whitish kernels with corrugated surfaces. Compare 
with normal kernels from the same or healthy heads of the same age, 
as to size and color. 
3. The glumes about the diseased kernels. Are they diseased? 
Compare with healthy. . 
It is from these diseased kernels that the honeydew oozes, but in the 
dried specimens, there is evident only the whitish covering of the dark 
diseased: kernels. 
Make a prawinc of the organs of a single diseased and healthy spikelet 
to bring out these characters. 
Later there is developed the ergot stage. Examine the specimens 
and photographs provided and oBsERVE:— 
4. The black spur-like bodies projecting here and there from 
between the glumes,—the ergots; average number from each head. Exam- 
ine illustration specimens of other ergot-infested grasses. DRAW a head 
of rye and a head of one other grass showing the ergots. 
Examine the loose ergots provided. NoTE:— 
5. The variation in size and shape; consistency; the surface, 
often checked and cracked. These ergots are sclerotia of the pathogene 
developed, in place of the host-kernel, from the structures of the Sphacelia 
stage, the shrunken remnant of which may often be observed still clinging 
to the tip of the sclerotium. 
6. On breaking one open, the light colored interior. These 
ergots are poisonous. 
Make an enlarged detailed pRaw1Nc of two or more of the ergots. 
ETIOLOGY 
The ergot is produced by the ascomycetous fungus, Claviceps purpurea. 
(Fries) Tulasne, the conidial or honeydew-stage of which was given the 
name, Sphacelia segetum Léveillé. 
Life-history. Several careful researches have resulted in a rather 
complete knowledge of the life-history of this pathogene. Primary and 
secondary cycles with sharply marked pathogenesis and saprogenesis. 
occur. 
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