A CONSIDERATION OF CURLY-TOP IN SEED BEETS. 25 



with a considerable number of apparently healthy beets of standard 

 varieties. 



The silos were opened April 10, 1908, and the beets were planted 

 April 10, 11, and 13 in the experimental field at Garland, Utah. 

 Within ten days they began to sprout. In the meantime the weather 

 was very severe, with great extremes of temperature. On May 24: 

 most of these beets had sprouted, and many of the pedigree beets 

 showed suspicious signs of curly-top. The closest scrutiny failed to 

 reveal the presence of leafhoppers at this time. On May 14 a can- 

 vass of the entire plat of seed beets showed the trouble to be more 

 widespread than at first supposed, though even at this date no leaf- 

 hoppers had been seen. By May 20 one portion of the pedigree beets 

 showed signs of the disease to the extent of 48.G7 per cent, and another 

 portion 29.36 per cent, as against 3.87 per cent among the standard 

 varieties. At this time a few beet leafhoppers had appeared on the 

 small plat that later became so badly affected. On June 8 the per- 

 centage of plants visibly affected was 52.21, 58.54, and 17.19, re- 

 spectively. The writer could not assign the cause of the outbreak 

 among the seed beets to the few leafhoppers then in evidence. In- 

 deed, the first cases of curly-top did not appear among seedling sugar 

 beets in the plat mentioned until about three weeks later, when the 

 insects had become much more numerous. 



The experiments hitherto described in connection with the work of 

 the beet leafhopper on sugar beets, whereby this insect was shown 

 to be the primary causative agent of curly-top, together with the ob- 

 servations just set forth, led to the conclusion that the disease may be 

 initiated in the seed beets by the hopper during the season preceding 

 their use for seed production. In order to determine this point con- 

 clusively it was arranged to take advantage of the outbreak of curly- 

 top in the small plat during 1908. To this end there were selected 

 from this plat about one hundred beets of good size and shape that 

 at the end of the season exhibited no visible signs of the disease ; also, 

 one hundred similar beets showing well-developed symptoms of the 

 trouble were selected from the same plat. All were carefully siloed 

 for planting in the spring of 1909. Many beets were also siloed 

 from the major portion of the field, where but few cases of the trouble 

 had appeared, though these latter plants had been infested by leaf- 

 hoppers during the later part of the season. 



Very early in April, 1909, these beets were planted out in the usual 

 manner. From the moment of planting, close watch was kept for 

 leafhoppers of any species. Almost with the first appearance of the 

 shoots of the seed beets from the affected plat of last season, whether 

 or not the beets had then exhibited symptoms of curly-top, the char- 

 acteristic curl and vein symptoms appeared. On May 24 all those 



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