308 
THE XATIONAL NUR8ERY:\rAN 
do not wisli to take the eonse(jLi(‘nees of defoliation and 
fruit drop due to the etfeet of unfavorahle weather eon- 
ditions upon aeid lead arsenate. 
The weather eonditions tliat are ])elieved to favor the 
deeoinj)osition of aeid lead arsenate are a sueeession oi 
li^ht rains extending over a period of several days, eon- 
tinual foggy or danij) ‘‘muggy" weather, and itiore or 
less warmth. A heavy rain is not as serious as a mist, 
^'or if there is a deeomjjosition of the arsenate, a I'ain 
suflicient to drij) from the leaves may wash off the soluhf * 
arsenie before its absorption. 
Weather Kecord for the Period of Spray Injury 
The follow ing weather reeord eovering the period of 
sjiray injury has been kindly furnisln'd by Mr. W. II. 
Ward of Morgan Hill., Hal., w ho was one of tlu' orehard- 
isls to suffer quite seriously from spray injury. 
The rain records are taken in the morning about 7 a. m. 
and are as follows: 
April 20 . 
April 26. 
April 27 . 
April 28 . 
Apidl 29 . 
May 1 . 
M ay 3 . 
. .66 inch 
.27 incli 
.14 incli 
.11 inch 
.11 inch 
.11 inch 
. 38 ineli 
May 4. 
.97 inch 
May 9. 
.20 inch 
May 10 ... . , 
.22 inch 
May 11 . 
.16 inch 
May 13. 
.18 inch 
May 16. 
. .31 inch 
May 23. 
.07 inch 
The spraying w as done on the Ward raneh on Ajiril 19 
and on the afternoon of April 20. The weather was 
damp when the spraying w^as done the first day and it 
rained the night follow ing. The siiraying w as finished 
the next afternoon. 
The amount of aeid lead arsenate used w as fi om 4 to 
41/4 Hjs. to 100 gallons of water. This was about the 
amount used by the other growers. The injury was no- 
tieed about two weeks after the ajiplication of the spray. 
Theories Confirmed ry the Investigation 
As previously noted, five samples of lead arsenate paste 
were collected during the progress of the 'investigation. 
These samples w^ere taken from parts of kegs of the 
paste wdiich were said to have been left over from the 
previous sprayings which had caused the injury. The 
labels were in some cases obscure, but from the informa¬ 
tion gathered from the labels, from statements by the 
growlers and by the dealer supplying the arsenicals, it 
seems that the five samples represented at least three 
different brands of lead arsenate. Examination revealed 
the fact that they were alt of the acid type. None of 
them contained an unusual or dangerous amount of 
soluble arsenic. In fact, one of the samples show^ed 
only a trace of soluble arsenic. The samples w(‘re in 
all respects normal as far as could be determined. Fur¬ 
thermore, the samples representing three different brands, 
it seems unyrobable Uiut all Ihree of I he com})anies should 
fuippen to produce a poor grade of material at the same 
time. 
The orchard of Mr. August Nielson in the Evergreen 
district near San Jose w as visited, w Inch consisted prin¬ 
cipally of apricots. There w'ere, however, three rows 
of a])pl(‘ trees running across this oi’chard. The whole 
orchard was sprayed with acid lead arsenate on April 
13. Five pounds of lead arsenate were used to the 100 
gallons. Foliage injury and drojiping of leaves and 
fruit was noticed before the first of May following. The 
whole orchard was uniformly sprayed with the strength 
of arsenical given above. It was noticed that spray in¬ 
jury occurred on the foliage of all of the apricot trees 
w hih' no injury could be detected upon the foliage of the 
a])ple trei's. The point brought out by the above ob¬ 
servation is that the stone fruits only were injured, that 
the ajiple trees were uninjured, and that the lead ar¬ 
senate used could not be considered of poor grade. 
The adjacent orchard of Mr. R. Chaboya was also vis¬ 
ited. This orchard consisted almost entirely of prune 
trees. Only a [lart of the trees in this orchard were 
sprayed, some of which were sprayed twice and some 
once. It w as observed that the most defoliation resulted 
where tw o sjirayings had been made. Wherever the 
trees had been sprayed, foliage injury was apparent. No 
foliage injury was obseiwed upon the trees wdiich had 
Princeton Nurseries through the portecochere 
not been sprayed. This observation, as w^ell as similar 
observations on other orchards, leaves no room for doubt 
that the injury had been caused by the spray. 
Observations w ere also made on a prune orchard owned 
by Mr. F. J. Shepherd, Edenvale. Only a part of the 
trees had been sjirayed. Those sprayed uniformly 
show ed injury, w Idle those not sprayed show^ed no injury. 
This ohservation confirmed the above. Many other or¬ 
chards w ere visited. To record the obseiwations made 
w'ould largely be a rejietition of the above. It w^as no¬ 
ticed, how ever, in this connection that occasionally a pear 
or an apjile tree had been s])rayed wdth the arsenical and 
in no instance' could injury be detected, while in every 
case w h('re stone fruits had been sprayed, wdth acid lead 
arsenate, more or less injury was apjiarent. 
j. Summary 
According to the observations made of stone fruits to 
w hich acid h'ad arsenati' had been applied during the 
month of April, 1913, they show ed injury to a greater or 
