New YorkK AGRICULTURAL EXPERIMENT STATION. 7g i 
ually increases from year to year until finally it becomes so 
destructive that a profitable, crop of onions can no longer be 
grown. Onion smut seems to be affected but little by weather 
conditions and is not subject to sudden fluctuations in virulence. 
MODE OF DISSEMINATION. 
Onion smut is chiefly a soil-inhabiting fungus. It rarely gets 
away from the soil except as it is carried on the bulbs. Unlike 
many fungi, its spores are not carried by the wind except, per- 
haps, for very short distances in times of heavy wind when 
considerable quantities of soil are moved. 
It is not carried on the seed, but on the bulbs it may travel 
long distances. It is carried short distances, as for example, 
from one field to another in the same neighborhood or from one 
part of a field to another part of the same field, on tools used in 
cultivation, on crates, barrels and bags, on the feet of men and 
horses, with onion refuse used as fertilizer, and by the washing 
of the soil during heavy rains. 
Many onion growers are accustomec to dispose of their onion 
refuse by spreading it on the land as fertilizer. This practice is 
to be condemned as it unquestionably serves to spread the smut. 
Unless it can be used on land not designed for growing onions 
or on land already thoroughly contaminated with smut (in which 
case the damage is inappreciable) it had better be allowed to go 
to waste. Especially is this true since the fertilizing ingredients 
in a ton of onions are worth only about 50 to 60 cents and a large 
part of this is lost by the escape of the nitrogen in decay. 
METHODS OF COMBATING THE DISEASE. 
BY THE USE OF LARGER QUARTITIES OF SEED. 
When much smut is present in the soil the chief difficulty is to 
secure a “ stand” of plants. To overcome this, onion growers 
are in the habit of using larger and larger quantities of seed as 
the smut increases year by year. 
