14 BULLETIN 734, U. S. DEPARTMENT OF AGRICULTURE. 



smut, i. e., seed immersed in a solution of copper sulphate (1 pound 

 of copper sulphate to 1 gallons of water) for three minutes is not 

 an -ffective method for killing the nematodes, because in this length 

 of time the solution does not pass through the hard covering of the 

 gall. 



The modified copper-sulphate treatment of soaking the seed for 12 

 hours in a solution of the strength 1 pound of bluestone to 25 gallons 

 of water has not proved successful in killing these worms. 



Experiments show that soaking seed in 0.6 per cent sulphuric acid 

 for 24 hours is an efficient method of killing the contents of the gall. 

 This sulphuric-acid treatment is so subject to variations in the hands 

 of an inexperienced operator that it can not be recommended for 

 treatment of seed infected with these galls, however, as the germina- 

 tion of the seed is greatly decreased. 



The hot-water treatment for smut, which is described in Farmers' 

 Bulletin 50T, 1 and which consists essentially of immersing seed 

 for 10 to 15 minutes in water at a temperature of 135° F., has like- 

 wise proved successful in killing the nematodes. This test, however, 

 unless properly carried out, is also liable to injure the sound seeds 

 and for this reason can not be recommended without reservation. 



The most feasible method of removing the source of infection from 

 sound wheat seems to be by floating the galls out in cold water. The 

 nematode galls are lighter than sound wheat kernels, and this differ- 

 ence in weight is made use of in their separation. A suggested 

 method follows: 



Have two tubs or half barrels, one set above the other so that the 

 overflow containing the galls will fall into the lower tub. Cover 

 the lower tub with cheese cloth to catch the galls but let the water 

 run through. Fill the upper tub with water to overflowing. Next 

 pour the infected wheat into the top barrel slowly at the same time 

 stirring vigorously. The galls and light chaff will rise to the top 

 and float off when assisted by hand or skimmer, and will be caught 

 on the cheesecloth over the lower tub. When vigorous stirring brings 

 up no more galls pour or drain off the water. Air drying is accom- 

 plished quickly and easily if the wet grain be spread out to dry on a 

 canvas or on a clean barn floor. The dampened grain should not be 

 allowed to lie in a heap as the kernels will not dry out regularly ; some 

 will sprout and danger of heating is present. 



The seed may be planted as soon as it will run freely in a drill or 

 may be dried thoroughly and stored for future use. Experiments 

 caiiied out by this method have resulted in the removal of over 99 

 per cent of the galls. It is recommended that the grain be allowed 



■ ' Johnson, Edward ('. The smuts of wheat, oats, barley, and corn. U. S. Dept. of 

 Agriculture, Farmers' Bulletin 507. VJ12. 



