

Pethybridge and Lm-feu'jy — A Disease of Flax Seedlings. 361 



Our attention was first drawn to it in the early part of the summer of 

 1916 by Mr. P. T. O'Hare, a.r.c.sc.i., Instructor in Agriculture in County 

 Antrim. Specimens, showing the same characteristic symptoms in each 

 case, were forwarded by Mr. O'Hare from several farms in that county ; and 

 observations made by one of us in the flax-fields in that and the neighbour- 

 ing counties in the following spring showed that the disease was by no means 

 an uncommon one, and caused in some cases no inconsiderable damage to 

 the young crop. 



II. — Symptoms of the Disease. 



The disease first makes itself evident to the ordinary observer when the 

 seedlings are only an inch or two above ground. The braird, as a whole, 

 or patches of it, presents a more or less sickly and pale appearance, which 

 farmers often wrongly attribute to frost. 



When individual diseased seedlings are closely examined it is at once 

 evident that, at least in the early stages, the trouble concerns primarily the 

 cotyledonary leaves. . On. them rounded, water-soaked areas are present, 

 which may arise anywhere on their surfaces. In a great many cases, how- 

 ever, the diseased areas are intimately associated with the adhering seed- 

 coats, which, particularly in the case of shallow-planted seed, are carried 

 above ground by the cotyledons. As time goes on these water -soaked, dead 

 areas increase in size, and exhibit a more or less distinct circular zonation. 

 The earlier attacked portions of the leaf become dried up, and, finally, the 

 whole leaf is killed. This state of affairs is illustrated in fig. 1, Plate XIX. 



Close examination shows that the diseased areas are not confined to the 

 leaves of the seedlings. In very many cases the young stems show small 

 lesions, which, at first sight, might be mistaken for damage resulting from 

 insect attack. These lesions, illustrated in fig. 6, Plate XIX., are sunken, 

 pale areas, which run longitudinally on the stems, and often originate from 

 the base of a previously affected leaf. 



Examination with the microscope shows that, in the majority of cases, the 

 epidermis on a diseased area is still intact ; and the sinking-in is due merely 

 to the contraction of the dead tissues. Sometimes, however, the contraction 

 is so great that actual rupture of the dead tissues occurs. 



It not infrequently happens also, especially at the ground-level, that the 

 lesion completely encircles the young stem. This results in the falling over 

 and ultimate death of the young seedling ; and the appearance thus presented 

 strongly resembles the condition often called " damping-off." 



More advanced cases of the disease can also be found in which the epi- 

 dermal and cortical tissues of the stems at or near ground-level have more 



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