364 OHIO EXPERIMENT STATION: BULLETIN 214 
‘ Dry-rot of potatoes is due toafungus (Fusarium oxysporum) 
which appears to belong among our soil infesting fungi. This 
fungus appears to be the cause of. premature dying of the potato 
plants and it certainly survives in the tubers from such infected 
plants. At harvest time, asshown under dry-rot of potato, tubers 
show infection at the stem end. Subsequently during storage the 
fungus penetrates more deeply into the tubers and will often produce 
dry-rot of the infected tubers. Further descriptive matter concern- 
ing dry rot will be found in the special part of the bulletin under 
potato. For storage of such infected tubers, as well as for the 
general crop, it is desirable that storage temperatures be kept about 
42 degrees Fahr., or slightly lower. 
Sweet pobitoes also suffer from a large variety of rot troubles. 
These sweet potato rots are more or less special in character and 
since the crop is not largely handled in cold storage, nothing is here 
offered in addition to what appears in the special part of the bulletin 
ONION ROTS IN STORAGE 
Onion rots area serious matter with onion growers and onion deal- 
ersas well. It has been found that particular varieties of onions in our 
climate are susceptible to special 
diseases. For this reason we 
must consider white onions such. 
as White Silverskin, White King, 
etc., ina separate class from the 
rots of red and yellow onions such 
as the Globe and Wethersfield 
varieties. 
With the white onions the 
problem is partly a field problem 
at harvest time, and partly one 
of storage. The growers are in 
the habit of gathering the white 
onions before the tops fall and . 
topping them immediately, in- 
stead of throwing together in 
heaps for absorption of the sub- 
Fig, 27. A white onion that has been de- 
stroyed bya blackneck or dry-rot fungus, Sc/e- 
rotium cepivorum Berk. This parasite has entered 
the onion through the green neck which was cut 
off at the time of harvesting the crop. (Froma 
photograph by T. F. Manns). 
stance of the tops by the onion 
bulbs as is practiced with the 
riper red and yellow varieties. 
After topping the white onions 
are placed in slatted crates, and these crates are stacked in the field 
or in open sheds where they are kept dry. Often the loss from rot 
during the six weeks following harvest may reach 60 percent of the 
