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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
then to the end of the summer, however, there was a remarkable 
scarcity of both, especially on the Rurals. Newly hatched nymphs 
appeared every day but, strange as it may seem, disappeared in a 
short time. This repellent effect of Bordeaux has previously been 
mentioned by Fluke. 1 
Untreated rows of each variety in this plot were heavily infested with 
adults and nymphs throughout the summer. 
Disease appeared after the second spraying on tips of leaves scat¬ 
tered all over the plot. No nymphs had hatched at this time. On 
the Rurals the disease remained without spreading to any extent until 
digging time. On the Green Mountains the disease spread very slowly 
and at digging time had not become serious, that is, probably not more 
, than one-fourth of any plant had dead leaves. 
On the untreated rows the disease spread without interruption from 
tip, to margin, to midrib, and all over the plants. At digging time 
Rurals showed some disease on every leaf; Green Mountains were 
badly diseased, many plants being dead. 
Bordeaux Mixture and Nicotine Sulfate. Two adjacent plots 
of equal size were planted to six varieties of potatoes—Early Triumph, 
Early Ohio, Irish Cobbler, Green Mountain, Late Puritan and Rural 
New Yorker. One plot was given maximum protection with five 
applications of Bordeaux 4-4-50, combined for the two last treatments 
with nicotine sulfate 1-1200. The other plot received no protection 
against the leafhopper. 
A very heavy infestation and frequent rains seemed at the time to 
demand five sprayings if maximum protection was to be afforded. 
It is probable, however, that four applications would have been 
sufficient. 
During the early summer leafhopper adults and nymphs were 
present in about the same numbers as on other plots, but by the middle 
of July there was a great scarcity of both. A week later prac¬ 
tically no nymphs and only an occasional adult could be found on the 
sprayed plots. This condition held up to digging time. 
The unsprayed plot was at all times rather heavily infested with 
both adults and nymphs, the numbers increasing as the season 
advanced. 
The treated plot immediately adjacent to a continual source of leaf¬ 
hopper infestation remained in excellent condition throughout the 
summer, the Early Triumphs being the one exception. (The seed of 
these came from plants killed by the disease the year before as pre¬ 
viously mentioned). A slight amount of disease appeared on the 
1 Fluke, C. L., Jr., “Does Bordeaux Mixture Repel the Potato Leafhopper ?’ 
in Jour. Eco. Ent., Vol. 12, No. 3, 1919. 
