24 THE CURLY-TOP OF BEETS. 



BEET GROWERS SHOULD BE ABLE TO RECOGNIZE THE LEAF- 

 HOPPER. 



It seems highly desirable that beet growers and field superintendents 

 should be able to recognize the beet leafhopper, so that its earliest 

 appearance may be noted. If successful preventive measures shall be 

 devised, it is very essential to be promptly informed of the first appear- 

 ance of leafhoppers in considerable numbers, so that such devices may 

 at once be put in operation. It has not been shown that any other 

 species of leafhopper is able to induce the curly-top symptoms, though 

 both Doctor Ball and the writer have independently experimented 

 with other species commonly found on beets. 



SERIOUS NATURE OF CURLY-TOP. 



The serious nature of curly-top may be understood when it is known 

 that in some localities practically the entire sugar-beet crop has been 

 destroyed. The writer has seen fields of beets completely denuded by 

 it. Furthermore, beets that do produce a root of fair size because 

 attacked comparatively late in the season possess a high percentage of 

 impurities and are on that account not so desirable to the sugar 

 companies. 



It may be said that beets once affected with curly-top never re- 

 cover. Even when the affected foliage is cut back repeatedly at in- 

 tervals of several weeks, the new growth exhibits unabated symp- 

 toms (29). 



A CONSIDERATION OF CURLY-TOP IN SEED BEETS. 



It has been observed by those who have raised beet seed in the re- 

 gions subject to the scourge of curly-top that a variable percentage 

 of seed beets will manifest symptoms of the disease with the first 

 shoots to appear in the early spring. This has been noted by several 

 members of the Office of Sugar-Plant Investigations and by Doctor 

 Ball (G). 



The following specific cases are good illustrations: In addition 

 to the cases of curly-top observed in June, 1907, among sugar beets 

 (see p. 13), the writer noted a fair percentage of seed beets thus af- 

 fected, but at that time little special attention was given the latter. 

 It was merely assumed that they might have contracted the disease at 

 the same time and in the same manner as the sugar beets, however 

 that might have been. No sugar beets exhibiting visible signs of the 

 trouble were selected for siloing in the fall of 1907. Among those 

 selected for use as seed beets were some of the pedigree and garden 

 beets referred to as showing a large percentage of curly-top, together 



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