MISSOURI BOTANICAL GARDEN BULLETIN 51 
size of a small pea they should be thinned out, eliminating 
the innermost grapes to permit the full expansion of a well- 
balanced bunch. The tendency in most cases is to underthin. 
However, with experience, the grower can readily judge the 
number to thin out. This operation is usually accomplished 
with the aid of a forked stick to steady the bunch while the 
undesirable grapes are cut out with special grape-thinning 
scissors. Care should be taken to avoid touching the grapes 
with the fingers, for if the glaucous covering is rubbed off, 
the fruit is spoiled for commercial use. 
CONTROL OF INSECT AND FUNGOUS PESTS. 
Mealy Bug—Usually present under the bark. Treat the 
dormant vines with wood alcohol, removing loose bark. 
Red Spider.—This is one of the worst pests, occurring upon 
both the leaves and fruit. If unable to control by forcible 
spraying, regulation of temperature, and ventilation, spray 
with nicotine or use powdered tobacco. 
Thrips—Punctures the surface of the leaves and tender 
shoots and sucks the juices. Spray with nicotine or dust with 
tobacco. 
Vine weevil—Feeds upon the leaves, leaving small holes. 
Control by hand-picking or hydrocyanic-gas fumigation ; also 
by spreading cloth under the vines and collecting the weevils 
after shaking the vines. 
Mildew—Causes the skin of the fruit to harden, thus check- 
ing development; also discolors the leaves. Sudden drafts 
and a drop in temperature induces this disease and should be 
avoided. Sulphur fumigation. 
Rust—Appears upon the fruit after thinning. Said to be 
due to handling the fruit during this operation. 
BEST VARIETIES FOR FORCING. 
Early—Black Hamburg, Appley Towers, Madresfield 
Court, Foster’s Seedling, Buckland Sweetwater, Royton 
Muscat. 
Mid-season.—Muscat of Alexandria. 
Late—Black Alicante, Alnwick Seedling, Gros Guillaume 
(also called Barbarossa), Gros Maroc, Gros Colman, Lady 
Hutt, Madresfield Court (both late and early variety). 
