70 REPORT OF THE BoTANIST OF THE 
The sulphur-lime treatment is recommended whenever the loss 
from smut is as much as one-third of the crop. The treatment 
would be greatly facilitated and cheapened by the construction of 
a drill which will apply sulphur, lime and seed at one operation. 
It is further recommended that onion growers investigate the 
transplanting method; also try to develop the culture of some 
other crops to rotate with onions, 
NATURE OF ONION SMUT, 
Smut is a fungous disease which attacks onions grown from . 
seed. The fungus causing it, Urocystis cepule, is related to the 
grain smuts, but different from them. So far as known the 
onion smut attacks no other plant than the onion. It kills great 
numbers of the seedling plants soon after they come out of the 
ground; and many other plants not killed outright by it are much 
injured, so that they die later or produce small and misshapen 
bulbs which are liable to rot. 
If a seedling onion plant affected by smut be examined the 
affected leaves will be found to be not only enlarged but often 
distorted and if the smut is nearly mature the leaves will appear 
abnormally dark in color and often show black streaks. Upon 
breaking open the leaves they are found to contain a black pow- 
dery mass which is composed of the spores of the onion smut 
fungus. These black masses of smut spores also occur on the 
bulba. 
AMOUNT OF DAMAGE DONE, 
Smut is, perhaps, the most destructive of all onion diseases 
and is common in nearly every section where onions are grown 
extensively. There are, however, localities where it is unknown. 
In this State it is very troublesome in the onion fields of Orange 
County while in the Madison County onion district it appears to 
be wholly absent. 
It usually does not become destructive in a field until after 
onions have been grown for several years in succession. When 
onions are grown continuously on the same land the smut grad- 
