22 
to areas a half inch or more in diameter. The fungus does 
not injure the potatoes directly, but it detracts from the ap¬ 
pearance of the tubers when offered for sale. But the im¬ 
portant point is, that when infected potatoes are planted the 
fungus is planted with them, and thus the disease is propa¬ 
gated year after year. 
The fact that the fungus attacks the roots of alfalfa com¬ 
plicates the treatment, since alfalfa is commonly used in the 
rotation of crops. If potatoes free from the disease are 
planted on land which has been in alfalfa within two years, the 
chances are that the crop will be affected, providing there 
has been any of the fungus on the alfalfa plants. The 
length of time that the fungus will -live in the soil is not 
known. German authorities state that it will persist for at 
least three years. Neither has the kind of crop which 
should be grown on infected land to starve the fungus been 
definitely determined; however, it is not known to attack 
our common cereal crops. 
It is too early to recommend a line of treatment to 
overcome the above conditions, since the cause of the trouble 
is not positively known, but potato growers who have been 
troubled in this way may find it profitable to take certain 
sanitary precautions. Such measures consist in planting po¬ 
tatoes, on land on which potatoes, beets, alfalfa or clover 
have not been grown for at least three years, and potatoes 
that are free from disease should be used for planting. If 
there is reason to suspect that the seed potatoes are in¬ 
fected with fungi, they may be treated with corrosive subli¬ 
mate or formaline, as is recommended for potato scab. 
Formulae for Treating Diseased Seed Potatoes. * 
Corrosive sublimate.1 ounce 
Water.8 gallons 
Dissolve the corrosive sublimate ’n one gallon of hot water, then di¬ 
lute with seven gallons of water. Allow the potatoes to soak one and one- 
half hours. When dry they may be cut and planted, though it has been 
found to be a good practice to treat the potatoes a week or more before plant¬ 
ing, si* ce the treatment mav retard germination ifdonejust before planting. 
Corrosive sublimate is a deadly poison, and it should be used in wood¬ 
en or earthen vessels, since it corrodes metals. 
Formaline.8 ounces 
Water.15 gallons 
Soak the potatoes two hours in this solution, preferably but a short 
time before planting. This solution is somewhat more expensive than the 
corrosive sublimate treatment but has the advantage of being lion-poison¬ 
ous, and it may be used in any kind of a vessel. 
* Jones, L. R., and Edson, A. W., Vt. Sta. Bui., 85. 
