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Wisconsin State Horticultural Society / Annual report of the Wisconsin State Horticultural Society for the year ending July 1, 1921
Vol. LI (1921)

Fracker, S. B.
Dusting to control fruit insects,   pp. 95-97 PDF (772.7 KB)


Page 96


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96           FIFTY-FIRsT ANNUAL REPORT OF
Further study showed conflicting data in the codling moth
work. A study of the weather records proved that the applica-
tions made for the second brood, in which the dust was only
half as effective as the spray, were soon followed by heavy rains
and that the latter were a limiting factor.
The New Jersey results against leaf hoppers show that "the
90-10 dust impregnated with one per cent nicotine is as effective
as that charged with three per cent, and only a little more than
one-half as effective as the liquid treatment." Against recently
hatched aphids also, the liquid materials gave better results,
though the dust of one per cent strength or higher was decidedly
effective.
Dr. A. L. Quaintance presented a summary of the dusting and
spraying results of the U. S. Bureau of Entomology from 1915-
1920. At Benton Harbor, Michigan, liquid applications in 1915,
1916, and 1917 resulted in from 87 to 97 per cent freedom from
codling moth, and dust applications in from 80 to 98 per cent
of fruit free from worms. With curculio the liquid spraying
yielded 83 to 94 per cent clean fruit and dusting practically the
same figures except in the case of one experiment, where only
5 per cent of arsenate of lead was used, the results being unsatis-
factory. Against apple scab the dusting efficiency was only 15 to
87 per cent as compared with spraying, which yielded 83 to 95
per cent. In all cases several different dust mixtures were tried,
but the results did not conclusively favor any one formula.
In Virginia, Arkansas, and Connecticut, codling moth and plum
curculio were controlled by dusting to the extent of at least
84 per cent, except when the insects were extraordinarily abun-
dant. The per cent of scab-free fruit, however, went as low as
30 per cent among the dusted trees. In Grand Junction, Col-
orado, dusting is nearly a total failure against codling moth, as
this insect is unusually severe in the semi-arid region.
While cost was not discussed at Chicago, Bulletin 171 of the
Oregon station publishes an analysis of the expense in the Hood
River valley. The average cost per acre in 1920 for the entire
program, including labor and materials, was $28.00 using spray
guns, $33.00 in the case of spraying rods and nozzles, and $31.77
in the case of dust.
The conclusion reached by every speaker was that while dust-
ing yielded some favorable results, it was less efficient, less suc-


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