338 OHIO EXPERIMENT STATION: BULLETIN 214 
It has not been found possible in thé cases of seed peas when infected 
with the blight fungus, or of seed wheat, rye, etc.,infected with the 
scab and other fungi to apply any seed treatment which would 
destroy the infecting fungus without destroying the vitality of the 
seed grain. In genera] we may say that where the seed infection or 
fungus spores, etc., are external to the visible or germinable grain, 
seed disinfection through treatment is possible, but for the internal 
fungiitis rarely possible. The loose smut of wheat may be amen- 
able to special seed treatment with only partial loss of vitality in 
the seed wheat. 
Fig. 18. Potato tubers attacked by Dry Rot Fusarium, showing sections near the stem-end of 
infected potatotubers. This infection may be easily discovered by cross sections made with a sharp 
knife, and sections from sterilized tubers gives culturesin Petri disnes. At times the discolorations 
extend to the middle of the tuber. (From a photograph by T. F, Manns). : 
METHODS OF SEED TREATMENT 
The methods of seed treatment heretofore employed are set 
forth in the spray calendar and consist in an immersion of the seed 
in hot water of definite temperatures or in solutions of formaldehyde 
of different strengths. The formaldehyde solutions may also be 
employed to sprinkle piles of seed grain and in this manner less 
handling of the grain is required. More recently it has been pro- 
posed to disinfect seed potatoes, onions, forage, etc., through fumi- 
gation with formaldehyde gas liberated by boiling the solution, or 
better by mixing formaldehyde or formalin solutions with pulver-' 
ized potassium permanganate by which the gas is liberated. 
With seeds, tubers, roots, bulbs, etc., the limitations of the 
treatment are not so narrow and these may be immersed for longer 
or shorter periods in solutions of corrosive sublimate, formalde- 
hyde, etc., or they may be exposed to fumigation with gaseous 
formaldehyde as has just been stated. (See Seed and Soil Treat- 
ment, pages 344 and 345 following. 
