INJURIOUS INSECTS OF I909Q AND IQIO. 105 
Lear Spor: In moist seasons irregular brown or black spots 
are produced on the leaves. They appear first on the under surface 
of the leaf. Use control measures indicated under black rot. 
Powvery Mitpew: The powdery mildew appears as circular, 
flour-dusted spots on all above ground parts of the plants. Under 
favorable weather conditions it may become serious, since the flow- 
ers may be attacked and then fail to set their fruit, while the berries 
themselves may be attacked and then cease growth, finally dropping 
from the vine. Lack of ventilation, excessive shade and damp situ- 
ations are especially favorable for the spread of the disease. 
Dusting with flowers of sulfur when the blossoms begin to open 
and repeated dustings as occasion may demand usually controls the 
pest effectively. The treatment under black rot is also effective. 
ANTHRACNOSE—Birp’s Eye: This appears on the canes as 
small, dark spots with sunken, ash colored centers; it weakens the 
canes very greatly. The symptoms on the fruit are very much like 
those on the canes. The spots often have reddish edges. The dis- 
eased canes should be cut out as soon as they appear. In addition, 
spray as for black rot. 
Lettuce. 
Gray Motp: The disease first becomes apparent by reason of 
the wilted edges of the leaves. Later -the affected leaves may droop 
and die, becoming covered with a dirty, brownish gray fuzz. Proper 
cultural methods and care of the greenhouse will generally prevent 
the appearance of the disease. Good ventilation and a fairly con- 
stant temperature, which must not be too high, are essential. 
Witt: Healthy lettuce in the greenhouse may succumb to this 
wilt in a single day. Affected leaves appear as though they had 
been suddenly plunged into boiling water and then taken out again. 
A dense, white growth of fungus threads appears on parts which 
have collapsed. The fungus produces storage organs which persist 
throughout the winter, causing infection the next year. All affected 
portions should be removed in order to prevent the formation of 
these organs. The same general sanitary precautions mentioned 
under gray mold should be taken. In case the soil becomes infected, 
it should be disinfected with formalin used at the rate of 1 pound 
to 12% gallons of water; it may be necessary to change the soil 
entirely. 
Melons. 
See Cucumber. 
