CARATOVORUS SOFT ROT 
This is the best known and most common soft rot disease of plants. It 
affects a great variety of hosts in each of which it produces more or less 
characteristic and peculiar symptoms. 
SYMPTOMS 
In carrots or turnips. It was in the fleshy roots of the carrot that this 
disease was first carefully studied. Examine the diseased roots provided 
and OBSERVE :— 
1. The soft mushy character of the rotted tissues. Crush a bit 
of it between the thumb and finger. 
2. The fetid odor of putrefaction. 
3. That the rot is largely confined to the root. 
Cut through the lesion and NoTE :— 
4. The variations in color and firmness of the diseased tissue 
from the center of the rotted mass toward the healthy tissue. 
DRAW to show these characters. 
The rotting of the roots in the field is accompanied in its advanced 
stages by the sudden wilting of the leaves. 
In cabbage and cauliflower. In these hosts the soft rot frequently 
follows the black rot and causes in cabbage the so-called ‘‘stump-rot.” 
Study the diseased heads provided and oBSERVE :— 
5. That the rotting is largely in the base of the fleshy leaves (or 
in the fleshy head of the cauliflower). 
6. That the cabbage head is thus loosened from the stalk from 
which it may be readily lifted leaving a slimy rotten ‘‘stump.” 
DRAW to show these symptoms. 
7. The soft mushy character of the rotted tissues; color? 
8. The fetid odor of the decomposing tissues. 
Split one of the partially rotted mid-ribs of the leaf or a diseased 
branch of the cauliflower head. Examine and NoTE:— 
9. The differences in color and consistency of the diseased 
tissues as the healthy tissue is approached. 
In iris. This disease is very destructive to the iris both in Europe and 
America. Examine the diseased leaves provided and oBSERVE:— 
10. The soft rotted basal portion. Crush a bit of it between 
the fingers. If fresh material is available, split a healthy and a diseased 
leaf and compare as to color and odor. 
11. That the epidermis of the diseased portion is more or less 
intact forming a rather firm covering for the rotten mass within. 
12. The upper advancing portion of the lesion, firmer than below 
but dark and water-soaked in appearance. SKETCH external and internal 
view. 
13. That the tips and margins of some of the leaves rotted at the 
base are dying and drying out. How may this be explained? 
The most striking field-symptoms are the falling-over on the ground 
of the outer affected leaves or the shriveling and browning of the tips of 
the leaves of the cluster. This latter symptom is, however, easily con- 
fused with the dying of the tips due to a fungous spot-disease common on 
iris. (See demonstration specimen.) 
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