114 EXPERIMENTAL FARMS. 



APPEARANCE OF AFFECTED VINES. 



Leaves. — The older leaves normal as to size, bub lighter in colour than normal ; 

 leaves towards the ends of the canes only partially developed thin, j'ellow to light, 

 yellow in colour. 



Canes. — Short jointed ; tendrils often abortive. The trouble manifests its presence 

 by the appearance of yellow coloured areas upon the leaves ; these extend until the 

 entire leaf is involved. Growth is checked and becomes sluggish as the leaves turn 

 yellow. When the vine is seriously affected, the older leaves drop off, the younger ones 

 turn deep yellow, remain only partially developed. This with the short-jointed character 

 of the wood renders such vines easily recognizable in the vineyard. 



Roots. — The root system of affected vines is very imperfect. As the trouble pro- 

 gresses, the laterals lose vitality, decay and fall away, so that a badly affected vine has 

 only the larger system of roots. The lower rootlets appear to die first, and vines were 

 examined which had completely lost the roots originally thrown out from the base of the 

 cutting. The vines most affected in Mr. Hagar's vineyard were those situated on the 

 lower levels and were chiefly confined to Concord's and Moore's Early. This vineyard, 

 in common with many others in that vicinity, is situated near the base of the ridge 

 which bounds the peach belt along the shore of Lake Ontario 



Mr. Hagar has lost over one hundred vines of Moore's Early and Concords from 

 this cause Mr. Hendershott's vineyard at St. David's is similarly situated, and is 

 flanked by the limestone ridge. As in the case of Mr. Ha2;ar the vines on the lower 

 portions are usually effected more than those on the higher levels. Roger's varieties, 

 Moore's Early, and Concord suffer most, while Niagara seems to be fairly exempt. The 

 malady makes its appearance soon after growth begins and reaches its height about the 

 end of June or middle of July. In cases of mild attack it may disappear to a large 

 extent as the season advances, notably more pronouncedly during dry seasons than in 

 wet ones — though this may not be considered an invariable rule. Vines lightly affected 

 frequently recover sufficiently to perfect their fruit. Those badly attacked lose their 

 fruit after the leaves. Moore's Early succumbs more readily than other varieties and 

 dwindles down to unhealthly sprouting crowns in two or three years. 



Microscopic Examination. — Parts of the affected plants were submitted to Mr. J. 

 Dearness, London, Ont., who kindly reports as follows under date of 6th July : — 



" The cause of this disease of the grape is obscure to me. In petioles of discoloured 

 leaves and peduncles of the fruit bunches, I find abundance of minute oval to round 

 spore-like bodies requiring a high magnification to define, but no mycelium or other 

 vegetable phase of an ordinary fungus. These may be bacterial, possibly produced in 

 the disorganized tissue without being the cause of it. The small branches of the root 

 have a diseased appearance, but although T have teased a number of scrapings, shreds 

 and sections of these under the microscope, I fail to find fungus or eggs, sloughs, etc., 

 of aphides or Phylloxera. The roots from the thickness of a pencil upwards seem all 

 right. May there be some injurious cause affecting spongioles and absorption areas of 

 th« root tips 1 So far as I can form an opinion it inclines to locating the disease in the 

 green tissues of the plant. In section after section through the petioles the cambium is 

 destroyed, medullary rays more or less collapsed, in fact nothing left retaining form 

 but cortex bundles and pith." 



Specimens were also submitted to the chief of the Division of Vegetable Pathology, 

 Washington, D.C., but nothing definite was learned* regarding the cause. Mr. Galloway 

 writes that " the specimens show no fungus attacks, such injuries might result from the 

 plants being in dry soil or wet soil. Grapes affected with a root rot due to a fungus 

 sometimes behave in the manner described by you." 



Remedial Experiments. — Presuming that the trouble might be due to unfavourable 

 soil conditions producing imperfect nutrition, some fertilizer experiments were planned 

 and commenced last spring at St. David's and at Grimsby. 



