LEAFHOPPERS OF THE SUGAR BEET. 41 
ECONOMIC RELATIONS. 
The first fact observed in 1905 was that different fields were affected 
very differently, and much time was spent in studying conditions in 
an attempt to discover just what combination of factors was neces- 
sary to produce the " curty-leaf," so fatal to the beets. Even in the 
worst fields examined there would be here and there a beet that was 
apparently untouched and growing as usual, while in the best fields 
only here and there could an affected one be found. 
As a result of the season's observations there seemed to be little 
question that the " curly-leaf " condition was the result of the attack 
of the leafhoppers combined with the effect of a very hot, early 
season. 
In many places it was noticed that along the edges of the fields 
where the beets had any shade — such as would be furnished by a 
hedgerow, or even by a vigorous stand of sweet clover on a ditch 
bank — there would be a marked difference for the first few rows. 
In Sevier County, where many of even the early-planted fields were 
abandoned and where the rest averaged from 2 to 4 tons per acre, 
one field was seen that did not show much damage and yielded 12 
tons per acre. This field had a block of tall poplar trees on the south 
and a row of equally tall ones on the west side. In other places it 
was observed that the fields that were the weediest had better beets 
than those that had been well cultivated. Under ordinary condi- 
tions the results in all these cases would have been just the reverse, 
and the only explanation that seemed plausible was that the shade of 
the trees and of the weeds kept the ground from becoming quite so 
hot and thus allowed the beets to overcome the effects of the leaf- 
hoppers. In ordinary practice the beets are not irrigated until they 
have made considerable growth; thus the taproot is forced to de- 
scend for water, and a long, symmetrical beet results, while if watered 
too soon the beets are short and sprangly. In one place, in 1905. it 
was found that the water had escaped from a ditch and irrigated one 
corner of a field much earlier than it had been applied to the rest, and 
this corner was the only place that was not seriously affected with the 
u curly-leaf.'' In another place the water supply failed just as they 
started to irrigate the field, and the remainder was not irrigated until 
a week later. The difference in the amount of " curly-leaf " on these 
beets showed plainly to the end of the season just how far the early 
water reached. At first these differences were attributed to the effect 
of the early water on the beet itself, but on further investigation a 
number of fields was found where subirrigation was depended upon 
entirely and where, ordinarily, fine beets were raised. In these fields 
the taproots of the beets were found to extend into a stratum of satu- 
rated soil and yet the beets were badly affected and continued to grow 
