18 BULLETIN 1029, U. S. DEPARTMENT OF AGEICULTUEE. 
been observed where alternate rows or groups of rows in the main 
field, from two different seed beds, resulted in one lot of plants wilt- 
ing badly from black-leg, while the other was not affected. An in- 
stance of this is shown in Plate I, B. Thus, although exact experi- 
mental data have not been obtained, these general field observations 
indicate that, under Wisconsin conditions at least, the spread of the 
disease in the main field is not nearly so important as that in the seed 
bed or during transplanting. 
SEED-BED TRIALS AT MADISON, WIS., IN 1919. 
In order to supplement experiments performed in the laboratory, 
treated samples of seed from lots Nos. 2-18 and 3-18 were sown out 
of doors. Each of these lots contained a small percentage of infected 
seed. A level strip of silt-loam soil was selected, which had not 
grown cabbage for at least seven years. Single-row plats 7 feet long 
and 18 inches apart were used. Two-gram samples of each treat- 
ment were planted on May 10 and 12. The various treatments in- 
cluded with the final results obtained are given in Table VII. 
In the check plats of untreated seed which were sown on May 14 the 
disease appeared on June 9 and was fairly well advanced by July 1, 
the normal time for transplanting. In all the treated plats the ap- 
pearance of the disease was materially checked. On June 20 four 
centers of disease were found, one in each of the 12, 24, and 48 hour 
treatments of lot No. 2-18 with dry heat at 85° C, and one in the 
24-hour dry-heat treatment of lot No. 3-18 at the same temperature. 
In the last case the disease had spread to 15 adjoining plants and to 
one of the adjoining plants in the case of another center. On June 27 
one infected plant each was found in the formaldehyde 1 : 256 30- 
minute and the 1 : 128 1-hour plats. Thus, up to that date very 
little disease had developed, and had the plants been set in the field 
at this time, which would have been the normal time for transplant- 
ing, the disease would probably have been very successfully con- 
trolled. 
In order to give the parasite all possible opportunity to develop 
in the plats, however, the plants were not disturbed until July 31, 
when they were all pulled and examined for black-leg. The data 
given in Table VII show that the disease continued to develop and 
spread from primary centers during July. Very few plats were en- 
tirely free from the disease, which is in general accord with the re- 
sult of laboratory experiments. 
