DISEASES OF THE GRAPE IN ONTARIO IN 1904 



W. T. 



MACOUN, HORTICULTURIST, CENTRAL EXPERIMENTAL FARM, OTTAWA. 



KNOWING that rot was causing serious 

 damage in a number of vineyards in 

 the Niagara peninsula, I took an opportunity 

 during September, to visit some of them 

 in the hope of learning facts of value in re- 

 gard to the diseases of the grape. Accom- 

 panied by Mr. W. H. Bunting, of St. Catha- 

 rines, 1 visited his vineyard and others in 

 the neighborhood of St. Catharines and 

 found that Mr. Bunting had sprayed seven 

 times and his fruit was only slightly injured. 



When the grapes were the size of peas 

 Mr. Bunting had bagged i,ooo bunches in 

 order to find out if infection took place be- 

 fore that time. Most of the bunches thus 

 bagged were perfect, but some had the black 

 rot in various stages of development, show- 

 ing that infection had taken place before the 

 grapes were as large as peas. The Niagara 

 grape was the variety most aiTected. Sev- 

 eral vineyards of Concord near Mr. Bunt- 

 ing's were examined, but black rot had not 

 worked to any extent in them. Brown rot 

 was, however, found in one vineyard, but 

 had not done much injury to the fruit. 

 Another vineyard, containing about 15 acres, 

 was visited, consisting principally of Con- 

 cord, Brighton, Niagara, and Moore's 

 Early. Of Niagara and Brighton there 

 was scarcely a sound grape anywhere, and 

 none of the bunches of Concord, even with 

 manipulation, could be made fit for market. 

 Moore's Early was not afifected. This 

 vineyard had not been sprayed. 



The infection by the olack rot as it ap- 

 peared in the vicinity of St. Catharines was 

 first noticed on the fruit as a round, brown- 

 ish spot about the size of the head of a pin. 

 This brownish appearance gradually spread 

 over the surface of the berry, and by the 

 time one-third of the surface was covered 

 the original brown spot had become paler, 

 showing distinctly the mark of infection. 

 After the whole grape became brown, the 



tissue gradually shrunk and dried, and wheu 

 thus shrunken the fruit appeared black and 

 prominently and irregularly ridged, the sur- 

 face being covered by small black postules. 



THE BROWN ROT. 



The vineyards of Mr. Murray Pettit, of 

 Winona, Ont., and others in that vicinity 

 were also visited. No black rot was 

 noticed at Winona, but brown rot was quite 

 abundant, and while it had not caused such 

 damage as .the black rot, it had done con- 

 siderable injury. The leaves of the vines 

 affected with brown rot had a downy ap- 

 pearance underneath. The affected fruit 

 first showed a brownish spot or patch on one 

 side and a shrinking of the tissue. The 

 brownish appearance spread all over the 

 grape and the whole grape eventually shrunk 

 into a hard shrivelled mass. When badly 

 afifected the vine loses a large amount of 

 foliage. Powdery mildew was also found 

 in these vineyards. 



The Niagara grapes, both in Mr. Pettit's 

 and adjoining vineyards, were affected this 

 year with either a new disease or more pro- 

 bably, as Prof. Selby suggests, a condition 

 caused by either powdery mildew or brown 

 rot affecting the stem to which the grape is 

 attached. This disease causes a hardening 

 of the grape and gives it a pale, unhealthy- 

 color. 



Another disease of the grape which was 

 doing a great deal of injury at Winona was 

 what we took to be the grape-leaf blight, a 

 disease which has not received the attention 

 that it deserves. This blight causes the 

 leaves to wither and drop, thus preventing a 

 free circulation of sap and the proper de- 

 velopment and maturing of the fruit. 



PERSISTENT SPRAYING REQUIRED. 



The diseases of the grape can be con- 

 trolled by thorough spraying, but the work- 

 must be done persistently and carefully. 

 The following are descriptions of some of 



* Rxtra-t from an address delivered at the annual convention of the Ontario Fruit Growers' Association held in Toronto, Noverabet 

 16-18, in connection with The Provincial Fruit, Flower and Honey Show. 



