a. Ss 
The Potato Leafhopper and Its Control. 13 
in every case was worse on plants which had come from tubers of 
diseased vines of the year before than on plants coming from tubers 
of healthy vines of the year before. 
It is hoped that it may be possible in time to develop a strain of 
some varieties resistant to ‘“‘hopperburn.” 
CONTROL OF THE LEAFHOPPER AND PREVENTION OF 
‘“HOPPERBURN.” 
USE OF BORDEAUX MIXTURE. 
Results of two years’ work have shown that Bordeaux mixture 
will repel the leafhopper, control ‘hopperburn,’ and is the best 
Fic. 11.—Potatoes protected from “hopperburn” by use of Bordeaux mixture: yield high. Five 
varieties shown here were given four sprayings with Bordeaux. Very little “hopperburn”’ present 
on August 23. Compare with figure 12. 
remedy. Bordeaux mixture made according to the 4—4—50 formula, 
containing 4 pounds copper sulphate and 4 pounds unslaked lime to 
50 gallons of water, was used. 
Bordeaux combined with nicotine sulphate acts a little more quickly 
in ridding vines of leafhoppers than does Bordeaux alone, but the 
results obtained do not appear to justify the added time and expense 
of using the nicotine. 
Nicotine sulphate and soap combined were found very effective in 
killing nymphs and a few adults present when the spray was applied. 
There was no lasting effect, however, because leafhoppers reappeared 
in afew days. ‘‘ Hopperburn”’ was not controlled. 
