LEAFHOPPERS OF THE SUGAR BEET. 41 



ECONOMIC KELATIOXS. 



The first fact observed in 1905 was that different fiekls were affected 

 very differently, and much time was spent in studying conditions in 

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

 sar}^ to produce the " curly-leaf," so fatal to the beets. Even in the 

 worst fields examined there w^ould 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 man}' places it was noticed that along the edges of the fields 

 Avhere the beets had any shade — such as would be furnished by a 

 hedgerow, or even by a "sngorous 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 -1 tons per acre, 

 one field was seen that did not show much damage and jaelded 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 ordinars^ practice the beets are not irrigated until they 

 have made considerable gi'owth; 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 sprangl3\ In one place, in 1005, 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 

 " 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 w^eek later. The difference in the amount of '' curly-leaf " on these 

 beets showed plainh^ 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 wdiere 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 



