8 BULLETIN 842, IT. S. DEPARTMENT OF AGRICULTURE. 



length, remain green longer and therefore mature somewhat later 

 than the normal ones, and the glumes protrude decidedly outward 

 and give a somewhat thickened appearance to the shortened spike. 

 Depending upon the severity of attack, some or practically all flower- 

 ing glumes on infected heads contain, in the place of normal kernels, 

 hard, light-brown to dark-colored galls which are filled with nema- 

 todes. These galls, though usually slightly furrowed on one side, 

 somewhat as are wheat kernels, are shorter and not uncommonly 

 thicker. This thickness of the galls often results in the spreading 

 of the inclosing glumes so as to expose the galls to almost full view. 

 As a consequence of this, wheat heads thus infected may be readily 

 detected in the field. When young, the galls are light to dark green 

 in color. They gradually become dark brown later, as the normal 

 wheat heads ripen. Because of a general similarity, they were in 

 France first confused with and mistaken for " smutted " wheat and 

 called " ble nielle," but only a simple test is necessary to distinguish 

 the two. A smutted grain is easily crushed by a little pressure and 

 becomes a mass of smutty powder, the black spores, whereas the 

 galls are hard and firm and break with difficulty. In Germany the 

 galls were first associated with the seed of cockle (Agrostemma 

 ffithago), a weed found commonly growing in wheat. This resulted 

 in the disease being designated there as " Radekrankheit." Only a 

 cursory examination, however, is necessary to distinguish the smooth 

 nematode galls from the black cockle seeds, which are covered with 

 rows of short spines. In England the trouble is perhaps most 

 commonly called " purples," on account of the color of the galls. 

 Farmers and millmen in sections of this country where the disease 

 occurs call wheat containing these galls various names, such as 

 smutted, bunted, cockle, bin-burnt, and immature wheat. There 

 have been instances, some of them recorded, where pathological in- 

 vestigators in this as well as other countries, without making micro- 

 scopic examinations, wrongly identified the galls as stinking smut of 

 wheat (Tilletia tritici or T. levis). Some of the differences in size, 

 shape, color, and general appearance between the nematode galls 

 and the material for which they have been mistaken are shown in 

 riate IV. 



DIFFERENCES BETWEEN THIS DISEASE AND TULIP-ROOT. 



It seems desirable to point out differences between the malady 

 discussed in this paper and the so-called stem disease, or " tulip- 

 root," of wheat and other cereals, which, while occurring in 

 European countries, has not been reported on wheat in America. 

 The two troubles have been confused both popularly and scien- 

 tifically, doubtless ow 7 ing to their occurrence together at times and 



