CULTURE OF GRAPE VINES UNDER GLASS. 319 



dropping off will, in a moist atmosphere, adhere to the 

 forming berry, and while being forced off by the growth 

 of the latter, it leaves its impression on the tender skin, 

 which increases in size as the berry grows and results in 

 the well known mark on the matured fruit called from 

 its appearance "rust." 



It is a good plan to jar the wire or trellis to which tha 

 vines are tied, when they are in flower, so as to cause a 

 movement of the pollen through the house. This will be 

 found to greatly assist in "setting" the fruit of such 

 varieties as Muscat of Alexandria, which does not some- 

 times set freely. 



THINNING. 



Only one bunch of grapes should be left on each 

 spur or shoot, if large bunches are desired. The 

 berries should be thinned when they are not larger 

 than peas ; if left until the bunches are crowded, the 

 process of thinning is not only much slower but the 

 berries are more apt to be bruised. I have long been 

 guided in thinning grapes by the fact (and one I think 

 not generally noticed), that the flowers of the grape are 

 produced in sets of three. In cases where each of the 

 three flowers form a berry, two may be safely cut out in 

 thinning; but in many instances two only are formed, 

 and sometimes only one, which the operator must take 

 into consideration in thinning. With large clusters it is 

 necessary to cut away entirely from the heart of the bunch 

 many of these sets of three alluded to. The large bunches 

 of some of the varieties ought to be "shouldered." that 

 is, the shoulders, or loose and overhanging portions of 

 the clusters, are to be tied up from the main body of the 

 bunch, giving opportunity for fuller development. This 

 is especially necessary with Hamburgs and Muscats. 



