220 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
To test the effect of humidity and partial shade, plants were inclosed 
in cloth (nainsook) cages. Under these conditions the plants re¬ 
mained without trace of hopperburn until the leafhoppers were added, 
when they developed this trouble as in other cases. Another experi¬ 
ment was carried on in a shaded greenhouse where potato slips were 
planted in moist sand. Burning developed on the leaves on which ' 
young nymphs were placed while those that were free from nymphs 
remained green and normal. 
These observations and tests, as well as others carried on, by no 
means solve all the problems in connection with the relation of the leaf- 
hopper to the burned condition, but they appear to furnish conclusive 
evidence that the hopperburn can be produced at will by the use of the 
leafhoppers and prevented as effectively by their elimination. Tip- 
burn has never been produced artificially in any other way and all the 
evidence points to the fact that its appearance in a field is strictly cor¬ 
related with the attacks of the leafhopper. If these conclusions are 
warranted then “hopperburn” as a name for the leafhopper effect on 
potatoes covers practically all that has formerly been designated as 
tipburn on this plant. Tipburn has, however, been indiscriminately 
used for burning effects of all kinds on various plants, shrubs and trees 
and the substitution of the name “hopperburn’’ for the specific burn¬ 
ing of the leaves caused by the potato leafhopper is justified in the 
interests of accuracy. 
Mr. G. G. Becker: I would like to ask Dr. Ball whether in these 
experiments he noticed any correlation of the amount of curly dwarf 
and mosaic—anything that would confirm the work that was done in 
Maine some time ago. 
Mr. E. D. Ball: Curly dwarf and mosaic were not factors where 
we were carrying on those experiments. 
Mr. S. B. Fracker: I would like to know whether the leafhoppers 
are as numerous as they were a year ago. 
Mr. E. D. Ball: The leafhoppers were even more numerous this 
fall than they were a year ago. With such a remarkably short fall, 
they did not have a chance to go into hibernation as nicely as usual 
and that may make a difference in next year’s results. 
Mr. High: How long did you leave the cages out in the field? 
What was the approximate date you put them out and the date you 
brought them in? 
Mr. E. D. Ball: The cages were out in the field from the time the 
potatoes were planted until they were harvested. 
Mr. High: What time do you plant potatoes? 
