24 BULLETIN 1029, U. S. DEPARTMENT OE AGBICULTUBE. 
This was brought very forcibly to the attention of the writer in 
August, 1920, when such a case was described i3y a seed contractor 
in one of the mentioned localities. Stock " mother seed " of a given 
variety which later was proved to be infected with Phoma was dis- 
tributed among several seed growers in 1919. A trial row was 
planted in 1920 by the contractor, and when examined in August by 
the writer the plants showed a high percentage of black-leg. One of 
the 1919 plantings for seed examined in 1920 showed black-leg infec- 
tion on 25 per cent of the seed plants, 4 while the several other fields 
from the same "mother seed" were undoubtedly infected. Thus, 
approximately 2,000 pounds of commercial seed became infected as 
a result of the introduction of the parasite on a small quantity of 
stock seed. Much of such seed infection can be prevented by growing 
stock seed from seed heads carefully selected for freedom from dis- 
ease followed by careful inspection during the following season. By 
applying this method in Wisconsin black-leg has been successfully 
avoided and comparatively large quantities of disease-free "mother 
seed " have been produced. 
Black-leg has not as yet been reported from the Puget Sound 
region, and an inspection of more than 30 seed fields in that region 
in June, 1919, yielded no sign of the disease. Inasmuch as most of 
these seed fields are started from " mother seed " grown in the East 
or abroad and none of the growers practice seed treatment, it is 
inevitable that some infected seed is sown. It would seem from 
comparison with our Wisconsin experience that this absence of the 
disease, as noted in the seed fields, must therefore be attributed to 
local climatic conditions restrictive to the development of the fungus.. 
This was rendered the more probable by the results previously re- 
corded (11) with some Wisconsin-grown seed known to be infected 
with Phoma. This was seed No. 2-18, which, as used in Wisconsin, 
resulted in high percentages of infection before the end of the season 
(see Tables VII and IX). Of this, 2 pounds were sent to the Puget 
Sound section for propagation after treatment for 30 minutes with 
mercuric chlorid. This was sown at Mount Yernon, Wash., about 
May 25, and when it was inspected seven weeks later, July 11, only 
four infected seedlings were found in the entire bed. These were 
evidently cases of primary infection with no spread whatever to the 
adjacent plants. In 1920, samples from two lots of badly infected 
seed were sown in this locality and portions of the same lots sown 
at Madison, Wis. In the latter region the fungus appeared in 
numerous primary infections within two weeks, and the disease had 
become widespread by transplanting time (see Table VI). Since 
4 The writer is indebted to Mr. I. II. Vogol, of Cornell University, for information re- 
garding this field. 
