Page 95

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WISCONSIN STATE HORTICULTURAL SOCIETY          95
DUSTING TO CONTROL FRUIT INSECTS
By S. B. FRAcK.
This paper and the next consist of a report of the symposium
on dusting held at Chicago in December. So much interest has
been expressed in this method of applying insecticides that it
seems best to discuss the subject briefly at this time and outline
-the results of experiments in other parts of the United States
rather than wait until the Wisconsin experiment station tests have
been completed.
A special study of the control of sucking insects was the sub-
ject of the first report by Prof. P. J. Parrott of the Geneva, New
York, station. Dusts containing one-half, one and two per cent of
nicotine, respectively, were used.
Apple aphids were found unequally susceptible to the dust.
From 91 to 98 per cent of the common apple leaf species were
killed during a rainy period when the check trees lost 27 to 60
per cent from natural causes. The results were also satisfactory
against the currant aphis, apple leaf hoppers, and nymphs of the
four-lined leaf bug, but less so against the woolly aphis and po-
tato aphis.
Air currents, denseness of tree growth, cold and wet weather
and the presence of honey dew or waxy secretions- of insects were
found unfavorable for effective work. The high cost of nicotine
preparations at present, according to Professor Parrott, makes
the expense of dusting against sucking insects "almost prohibitive
for large operations."
The results outlined by Dr. T. J. Headlee of New Jersey in-
cluded work on codling moth, curculio, apple scab, and plant
lice. His first table, which is given herewith, indicates unsatis-
factory results against curculio, but successful applications against
scab.
Cureullo Per Cent      Scab Per Cent
Year             Location
Check   Dust  Liquid Check   Dsat   Liquid
Glasboro--_.-      29.1    4.4    5.5   22.2    0.0     0.0
19iL       _      _____     _ hVneland._______  70.3  43.8  31.6  51.9  14.8
 6.4
IML........hVeland----             --      -   3.68   3.38 ___      3.86
  19.69
117_____=          Haddonhl ____       no reCord            5-7.3   5.85
   2.52
49.7   17.12  18.66  48.97   7.90    9.53
I               __ _;