Fungous Diseases oe Colorado Crop Plants 
27 
This disease must not be confused with spray injury. Fruit and 
fruit stems are rarely attacked. 
Control .— (i) Spray with self-boiled lime-sulfur, 8-8-50: 
atomic sulfur 5-50; commercial lime-sulfur or Bordeaux 
mixture, 4-5-50 foTinula. 
(a^ First when petals fall, beginning' when they are three- 
fourths off. 
(b ) Ten days to two weeks later. 
(c) Three to four weeks before fruit is harvested. 
(d) In sections, subject to severe attacks, an application 
should be made just after the fruit is picked. 
(2) If possible, dispose of fallen leaves by fall or spring plow¬ 
ing. 
Black Knot. —See Plum, page 37. 
Crown Gall. —See Apple, page 12. 
CUCUMBER. 
Bacterial Wilt. —This is evidenced by a wilting of the leaves 
and runners. There is no indication of injury to the roots, such 
as blackening, or to the leaves and stems, such as spotting. The 
leaves even retain their green color for quite a time. The water 
tubes are plugged, thus causing a wilting. By squeezing an infected 
runner, there oozes a sticky, milky, stringy liquid. This wilt also 
occurs on the Hubbard squash and cantaloupes. 
Control .—Practice crop rotation. 
(2) Insects are important agents in the spread of the disease. 
Spray for squash bug and cucumber beetle. 
(3) Remove and burn affected parts promptly. 
Downy Mildew. —^This disease is found on almost all culti¬ 
vated species of the gourd family, such as cucumbers, muskmelons. 
watermelons, squash, and pumpkins. Affected leaves have irreg¬ 
ular yellow spots, which run together in serious attacks causing the 
entire leaf to yellow, shrivel, and die. A whitish downy mass tinged 
with purple can often be seen on the under side of the large older 
spots. In weather unfavorable to the disease, the spots remain small. 
The disease starts with older leaves, and spreads toward the ends 
of the vines. Hence the center of the hill is first killed. Very few 
cucumbers are produced on diseased vines. 
Control .— (i) Spray with Bordeaux mixture, 4-5-50 formula. 
(a) First application, when the vines begin to run. 
(b) Later sprayings, at interv^als of about ten days, if the 
weather is dry, and oftener if the disease spreads rap¬ 
idly. 
