_ _ Spraying Apple T rees. 9
i RESULTS WITH ABSENATE OF LEAD.
This insecticide is rapidly commending itself to progressive
· fruit growers because of the ease with which it can be kept in sus-
pension once thoroughly mixed with water, and particularly because
it has no injurious effect on leaves and fruit. Unfortunately, it is
not generally kept by local dealers in insecticides, and the time
required to get it from manufacturers and dealers at a distance
frequently has the edect of leading fruit growers to continue using
the better known and more generally available insecticide, Paris
· green. As used by the writer, arsenate of lead has not proved ef-
fective when mixed with water in the proportions ordinarily em-
ployed for Paris green. Some of our fruit growers have failed with ·
itbecause they were not aware of this difficulty. The strength (1
pound to 10 gallons) employed in these experiments may seem
j excessive, and certainly greatly increases the cost, but from my
experience with the poison, it seems to me doubtful if as good
results with codling moth will be obtained with very weak mixtures
of this insecticide.
` Three gallons of the mixture means an application of 4.8 ounces
of arsenate of lead per tree. With the poison costing sixteen cents
per pound, a single application of this quantity costs 4.8 cents per
tree, and two such applications as were given in the above experi-`
ments can be made at a cost of 9.6 cents for materials. This does
not seem excessive for a season’s spraying, provided the injury from
codling moth is sufficiently reduced.
Averaging the percentages of injury from eodling moth on the
V twelve trees sprayed with arsenate of lead (6 before and 6 after
the petals fell) gives 3.53 per cent. The percentages, it must be
remembered, are in all eases taken from the culls alone, and are
lower if derived from the total yield in each case. The average per
cent. of injury on the trees sprayed with arsenate of lead was just
about one—fourth as great as that on the trees sprayed with Paris
{ green and lime.
The average percentage of injury on the trees sprayed with
arsenate of lead while the trees were in full bloom was 5.39 as
· against only 1.67 on all the trees sprayed with this insecticide after
the petals had fallen. The percentages of injury suffered by the