Some Grape Troubles of Western New York, 423 



GROUP I. 

 Injuries caused by parasites. 



1. Insects. — It is believed by many that much, if not all, of the 

 shelling of grapes is due to the action of insects. This point was 

 constantly kept in mind during the examination of vineyards, and 

 both clusters and vines were searched for insects which might be 

 supposed to cause the trouble. In not a single case, however, did 

 I discover any pest to which could be attributed the shelling of 

 the grapes, and this theory had to be abandoned from want of 

 evidence. If the trouble is caused by an insect, it works "in 

 ways that are dark and devious ' ' and when found will prove to be 

 very interesting. 



2. Fungi. — A majority of the vineyards visited were found to 

 be infested with powdery mildew {Uncinula spiralis). This 

 was found growing abundantly upon the leaves and fruit- 

 stems of some vines and traces of it could be found in almost 

 every vineyard. This mildew appeared late and was not found 

 upon any berries. It formed a white mealy coating upon the 

 main stems of the clusters, but comparatively little was found upon 

 the pedicels of the individual berries. Its presence upon the 

 foliage could easily be detected by the silvery-gray appearance of 

 certain portions of the upper side of the leaf, these areas being very 

 plainly marked in those portions freely attacked. Almost the 

 whole of this fungus rests upon the leaf, and only the suckers 

 which are in search of nourishment enter into the leaf tissue. 

 This permits the parasite to be rubbed off very easily and the only 

 trace of its former existence upon the leaf is a darkening or black- 

 ening of the portion which was most thickly covered. 



In severe cases this fungus will cause grapes to fall from the 

 vines, for the following reason. Let us suppose that the stem of 

 a cluster is thickly infested with the mildew. A great many 

 suckers will be sent into the green portion of the stem and much 

 nourishment will be taken away from the berries. Another eflfect 

 will be to obstuct the free flow of sap and this will again cause the 

 berries beyond the point of injury to be deprived of the materials 

 which were originally intended for their use. "We sometimes 

 find nearly full-grown berries completely overgrown with mycel- 



