AFFECTED SEED BEETS ALMOST NONPRODUCTIVE. 29 



(2) The type with short, ovate, retracted leaves and short, bowed 

 petioles; tissue between larger veins puffed out as though the paren- 

 chyma had outgrown the fibro- vascular tissue ; veins generally rather 

 less knotted than in the preceding type; generally the early appear- 

 ance of abortive seed stems; almost entire inhibition of growth after 

 first month. This type is perhaps the most abundant one among 

 seed beets and is found also on sugar beets that succumb late in the 

 season after attaining a considerable size. (See PL III, fig. 1, and 

 PL V, fig. 1.) 



(3) The type with long, narrow, sinuous, thick, leathery-looking 

 leaves; without marginal curl or vein symptoms; no seed steins; 

 almost entire inhibition of growth after first month or six weeks; 

 dull, dark-green foliage, inclined to russet. (See PL IV, fig. 2.) 

 Noted only on seed beets. 



(4) The type with small rosettes of leaves similar to those of the 

 second type mentioned, but much smaller; very early cessation of 

 growth; no seed stems; very feeble vitality, yet root apparently quite 

 solid and crisp. (See PL V, fig.. 2, B.) 



(5) The type with root apparently as sound and crisp when planted 

 as the most healthy beet, yet making no growth at all. 



(G) The type with part of shoots affected with marginal curl, in- 

 ward; growth not otherwise seriously affected; part of shoots appar- 

 ently normal. 



(7) The type with no visible symptoms of the disease, but gen- 

 eral growth checked. (See PL VI, fig. 1.) 



(8) Combinations of any of the foregoing. (See PL V, fig. 2, A.) 



AFFECTED SEED BEETS ALMOST NONPRODUCTIVE. 



The serious nature of curly-top is heightened by the fact that few 

 seed beets affected by it produce seed. Of those possessing sufficient 

 vitality to produce seed stems, many dry up and die before maturity ; 

 the very few that produce seed are so puny and stunted as to produce 

 but a small fraction of a normal yield. Thus, it will be seen that, 

 while this species of leafhopper is a serious menace to the sugar-beet 

 crop, it is doubly so when beets are raised for seed. The beets may 

 be quite satisfactory for the manufacture of sugar and appear normal 

 and healthy when harvested, yet have stored within them an active 

 agent that may cut down the seed crop from a few per cent to entire 

 loss. 



PERCENTAGE OF LOSS OF SEED BEETS. 



When put in plain figures this loss is very striking. To revert to 

 the experiment just mentioned, those plants showing no curly-top 



181 



