40 BULLETIN 823. IT. S. DEPARTMENT OF AGRICULTURE. 
'7 
PULLING TESTS. 
Since the cucumber beetles originally become carriers through 
feeding on wilt-infected plants, it was thought possible that by 
pulling the wilted plants during the early part of the season an appre- 
ciable measure of control might be effected. Accordingly at East 
Marion, Long Island (May 24, 1916), 200 hills of Woodruff's Hybrid 
cucumber were planted in an isolated block, the location of which 
is shown in figure 1, Field IV. There were 800 plants in the field 
after thinning and at the time the first wilt appeared (June 29). 
Wilted plants were pulled and removed from the field 1 times through 
the season, on the following dates: June 29, July 11, 13, 18, 21, 27, 31, 
and August 11, 18, and 25. During the course of the season 249 
plants wilted, or 31 per cent of the total number left after thinning. 
In the control, untreated plats of spray-test Field Ha in this same 
locality (fig. 1) the amount of the disease varied from 45 to 56 per 
cent, while of about 1,000 unsprayed plants in Field II (fig. 1) 60 per 
cent wilted. Thus the control by pulling of wilted plants was 
entirely as effective as that by the weaker Bordeaux mixture used. 
This experiment was repeated in 1917, near Tuxedo, Md., using 
Arlington White Spine cucumbers. The number of plants left after 
thinning was 1,046, while 332, or a little less than 32 per cent, con- 
tracted wilt and were pulled during the season. The average wilt in 
the three untreated plats of the neighboring spray test was about 36 
per cent. Thus a slight difference is to be noted in favor of pulling 
the wilted plants, but the result is by no means so well marked as in 
the Long Island test. However, the Tuxedo plat was located in a 
field of cucurbits and was separated from other cucumbers and canta- 
loupes only by a strip of watermelons 3 rods wide, while the test plat 
on Long Island was about one-eighth of a mile from any other cucur- 
bits, and corn and other noncucurbitaceous crops occupied the 
intervening area. 
Clearly some measure of control is effected by the pulling of wilted 
plants, but the presence of a neighboring field where this control 
method is not practiced may largely nullify the good results. 
CONTROL IN GREENHOUSES. 
The senior writer has in some cases found serious damage from 
wilt on cucumbers in commercial greenhouses. In these instances 
the striped cucumber beetle has clearly been the first source of 
infection, though the greenhouse workers have sometimes continued 
the spread of the disease with much greater efficiency than the 
original carrier. Cases have been noted where wilt infection has 
followed down the row on one side of a greenhouse bed, taking nearly 
every plant, while on the other side of the same bed scarcely a single 
case could be found. Here the evidence is clear that pruning instru- 
ments were the carriers of infection. 
