B. P. I.— 563. 



THE CURLY-TOP OF BEETS 



INTRODUCTION. 



Through various publications the serious nature and general char- 

 acter of the curly-top of beets are fairly well known, either under 

 that name ° or more locally as " blight," " western blight," or 

 " whiskered beets." These names are descriptive of one or another of 

 the symptoms manifested by the stricken plants. Apparently no 

 kind of beet is immune. 



Recent experiments and observations have demonstrated not only 

 the primary cause of this disease, but that it is an even greater menace 

 to the production of beet seed than to the culture of beets for sugar. 



SYMPTOMS OF CURLY-TOP. 

 EXTERNAL. SYMPTOMS. 



The external symptoms of curly-top are numerous and may be 

 found in all parts of affected plants. Commonly the earliest to ap- 

 pear is an inward curling of the inner leaves from the entire margin 

 toward the midrib. Almost simultaneously a distortion of the veins 

 of the affected leaves may be noted ; these become crinkled and knotted 

 on the dorsal surface of the leaf (PI. I, fig. 1, and PI. II, fig. 1). 

 As the disease progresses more leaves, and finally the whole plant, 

 become involved ; nipple-like protuberances develop on the veins, 

 sometimes to the length of about three-sixteenths of an inch, and the 

 whole leaf becomes tightly curled from either side. The petioles 

 remain much shorter than in the normal plant (fig. 1) and become 

 bowed, with the concavity inward; the crown is generally quite per- 

 ceptibly wider than in the healthy beet, owing largely to an abnormal 

 growth of small and imperfectly formed leaves outside of and around 

 the original set of leaves; and the leaves and petioles bunch closely 



°" Blight" is used in so many other connect ions that it is deemed better to 

 avoid its use in this paper; neither is "curly-leaf" considered quite as inclu- 

 sive as " curly-top," since the latter term includes crown, petioles, leaves, and 

 seed stems. However, it is acknowledged that " curly-top " is uot an ideal name, 

 because it fails to include the disturbances found in the root. 



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