72 AMERICAN GRAPE GROWING 



f al treatment are not as well determined as are those for 

 black rot and some other affections. 



BITTER ROT (Greeneria fuliginea). This disease 

 takes its name from the bitter taste it imparts to grapes. 

 Ft generally appears when the berries begin to ripen, as 

 a brownish circle or spot, which enlarges until the en- 

 tire berry turns brown, though for a time it retains its 

 full size. Finally small, purplish pimples appear on the 

 surface ; the berry shrinks and falls. 



WHITE EOT (Coniothyrium diplodiella). This disease 

 attacks the fruit and its pedicles, as well p s the stem of 

 the bunch, but not the leaves or branches. The pedicles 

 become brown, the berries are at first very juicy; small 

 gray or brownish pustules appear on the surface, and 

 the berries dry up, assuming a grayish- white color, 

 which distinctly marks the appearance of this disease 

 from that of black rot. 



ROUGEOT is not a fungous disease, but is the result of 

 an interruption of the physiological processes in the 

 plant. It causes a break in the equilibrium which 

 should be maintained between absorption and transpira- 

 tion. In this trouble the leaves turn red or yellow in 

 spots or bands, and the vines are killed as a result of the 

 death of the leaves. The first reported appearance of 

 this disease on this side of the Atlantic was in 1890, 

 when it was observed in the central region of New 

 York. Its attack is marked by small, dark, irregular 

 blotches between the veins of the leaves. These spots 

 enlarge rapidly and darken to a dull purple or reddish 

 brown, which become confluent, the leaf-veins alone 

 remaining green or yellow. The contrast between the 

 affected parts and the green leaf- veins gives the foliage a 

 peculiar streaked appearance. In serious cases the leaves 

 at length curl up and fall, leaving the vine bare. This 

 denudation arrests at once the ripening of the fruit, and 

 leaves it flat, insipid and sour. In severe cases the ber- 



