LEAFHOPPERS OF THE SUGAR BEET. 41 



EC0N03I IC RKLATK )N-S. 



The first fact observed m 1905 was that different fields were affected 

 Tery differently, and mucli time was spent in studj^ing- conditions in 

 an attempt to discover just what combination of factors Avas neces- 

 sary to produce the " curly-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 groAving as usual, while in the best fields 

 only here and there could an affected one l>e 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 Avhere the rest averaged from 2 to -1 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 lioen well cultivated. Under ordinar}^ condi- 

 tions the results in all these cases would have been just the reverse, 

 and the onlj?- explanation that seemed plausible was that the shade of 

 the trees and of the Aveeds kept the ground from becoming quite so 

 hot and thus alloAved 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 Avater. and a long, symmetrical beet results, Avhile if Avatered 

 too soon the beets are short and sprangly. In one place, in 1905, it 

 was found that the Avater 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 

 *' curly-leuf." In another ])laco the Avater suj)ply failed just as they 

 started to irrigate the field, and the remainder Avas not irrigated until 

 a Aveek later. The difference in the amount of "curly-leaf" on these 

 beets shoAved plainly to the end of the season just hoAv far the early 

 Avater reached. At first these differences Avere attributed to the effect 

 of the early water on the beet itself, but on further iuA-estigation a 

 number of fields Avas found where subirrigation Avas depended upon 

 entirely and where, ordinarily, fine beets Avere raised. In these fields 

 the taproots of the beets Avere found to extend into a stratum of satu- 

 rated soil and vet the beets Avere bndlv affected and contiiuied to irroAV 



