NEMATODE DISEASE OE WHEAT. 33 
The writer has also separated nematode galls from small quanti- 
ties of diseased wheat by another method, which requires considerable 
care and effort for its successful execution. It is carried out by re- 
leasing water under pressure at the bottom of a receptacle which 
contains the infected wheat and stirring and roiling vigorously at 
the same time. If the water is released through a hollow rod at- 
tached to a hose the rod may also be used in stirring the grain. 
With such treatment the nematode galls and other light material 
will rise to the surface and may be easily removed. Whether this 
water method would be effective for use where large quantities of 
grain are to be separated has not been determined. 
In removing the galls by either of these means there is little likeli- 
hood that seed so cleansed will bear any living larvae on the surfaces 
of the kernels. Only rarely do the larvae escape from galls which 
are held under the usual storage conditions, and any that might es- 
cape would most likely be killed by the usual rubbing together of 
the kernels as the grain is handled. On drying out, the larvae become 
stiff and brittle and are very easily broken. However, in order to 
eliminate the possibility of transmitting any source of infection 
along with the sound kernels the cleaned seed can be treated with hot 
water at a temperature of 51° to 52° C. for 10 minutes, a treatment 
which the writer has found to kill unprotected larvae. According 
to Humphrey and Potter (17) this treatment is also sufficient for 
controlling loose smut (Ustilago tritici). If the hot-water bath is 
to be given, it should be applied directly after the wheat has been 
separated from the galls. 
Although the methods just described would seem to obviate the 
necessity of any other means of disinfecting the grain, another 
means of accomplishing equally good results is available. It con- 
sists of soaking the gall-mixed seed for about an hour in unheated 
water and immediately immersing it for 20 or more minutes in 
water held at a temperature of 52° C. Equally effective has been 
found either an immersion of the soaked seed for 15 minutes in 
water maintained at 54°, or for 10 minutes at 56° C. The writer 
has never been able to find living nematodes within galls given any 
of these treatments, although these observations are apparently at 
variance with those of Marcinowski (22), and Davaine (11), who 
report that they were unable to kill the organism by immersing the 
galls in water at a temperature of 54° to 56° C. for 10 to 12 minutes. 
Doubtless they did not previously soak the infected seed. This sup- 
position would account for the difference in results, as it takes a 
much longer time to raise the internal temperature of dry galls or 
seeds than that of those which are wet. 
