32 THE CURLY-TOP OF BEETS. 



once been started in a plant the ill effects continue long after the 

 initial cause has disappeared. If the insects are killed or kept off such 

 a plant the new growth will be free from spots and therefore appar- 

 ently healthy. It is, however, poor in reserve albumin and has an ex- 

 cessive amount of oxidizing enzyms * * * and is therefore in fact 

 diseased. This malnutrition becomes gradually cumulative from gen- 

 eration to generation of cuttings, and so far as our investigations have 

 gone, can not be cured." In this respect the behavior of curly-top 

 beets is almost identical, the most noteworthy difference being the 

 persistence of the visible symptoms in all new growth of curly-top 

 beets, even after repeated cuttings back of the foliage at intervals of 

 several weeks. 



In the cases described by Woods and others the visible effects of 

 the insect punctures are confined to the leaf, or even the portion of 

 the leaf, attacked, whereas, as just stated, the disturbance induced in 

 the curly-top beet affects the whole plant in such a manner that all of 

 the growing foliage shows visible symptoms of the disturbance. 



While curly-top is initiated in the same manner as stigmonose and 

 so far as can be discovered (29) can not be attributed to bacteria or 

 fungi, the physiological disturbances seem to bear a close resem- 

 blance also to those described by Woods and others (7, 15, 18, 19, 20, 

 23, 24, 25, 34) as mosaic. In -the case of curly-top it is true that the 

 rather conspicuous leaf mottling noted in the mosaic disease is ab- 

 sent, except for the faint mottling already referred to as occurring in 

 leaves of young beets affected by curly -top and visible only by trans- 

 mitted light, On the other hand, the general nutritional disturbances 

 and the unbalancing of normal enzym activities described by Woods 



(33) seem to be duplicated in curly-top beets; in the latter, too, there 

 is a similar persistence of visible symptoms. Still another feature is 

 common to both the mosaic disease and curly-top, viz, under both con- 

 ditions an affected plant will sometimes yield seed, and in each case 

 that seed is capable of producing normal, healthy plants. 



The writer has not yet secured conclusive evidence that these symp- 

 toms can be induced in beets by the methods practiced by Woods 



(34) in the case of the mosaic disease. Indeed, it would appear to 

 him difficult to do so, for the reason that the beet root contains so 

 large a reserve of nutrients. Townsend's experiments (29) and 

 some conducted by the writer seem to negative the idea, but further 

 investigations along this line are necessary. However, the writer is 

 of the opinion that there is a striking resemblance in the general be- 

 havior of curly-top beets to that of those suffering from the mosaic 



disease. 



This would indicate that curly-top is the most conspicuous and 

 destructive form of stigmonose and, at the same time, one of the 



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