20 Farmers’ Bulletin 1282. 
some growers object to it because of damage to closely planted rows 
from horse-drawn vehicles, the necessity of often going some distance 
for water, the inconvenience and delay of heating the soap, and 
because of the weight of the water which must be transported across 
the field. The use of nicotine dust also gives a satisfactory killing 
of the onion thrips, but its application involves none of the objec- 
tionable features of liquid spraying. 
The hand-operated dusters (Fig. 11) will cover from 24 to 8 acres 
a day, using from 30 to 50 pounds of dust per acre. A small power- 
operated duster, treating six rows at a time, was capable of cover- 
ing 10 to 12 acres a day. 
Fig. 11.—Dusting onions infested by onion thrips with hand-operated bellows duster. 
One grower, anticipating the need of contro] measures, planted 
a large field of onions in triplicate rows, i. e., in sets of three rows 4 
inches apart, with every two such sets 30 inches apart. This arrange- 
ment not only permits the use of the desired machinery for controll- 
ing the thrips, but actually makes it possible to grow about one-third 
more onions to the acre. A power outfit was placed on a wagon or 
truck, with a set of eight discharge pipes at the back, covering as 
many triplicate rows, or sets, with a pipe to each set of three rows. 
Figures 12 and 13 show the duster in action. With this it was 
possible to cover as much as 4 acres per hour. The most satisfactory 
control was obtained by using the 5 per cent strength, and up to 4% 
pounds per acre for the larger onions. When the air is quiet, and the 
dust does not drift away quickly, a smaller amount is sufficient. 
