20 BULLETIN 1029, U. S. DEPARTMENT OF AGRICULTURE. 
always be relied upon to yield successful control. This point will be 
emphasized further by data from commercial trials presented in the 
following pages. 
RESULTS WITH TREATED SEEDS IN COMMERCIAL FIELDS. 
To determine the practical value of cabbage-seed treatment, several 
lots of commercially grown seed, varying in weight from 2 to 400 
pounds, were treated before distribution in 1918 and 1919. All the 
seed except lot No. 14-18 was grown in the vicinity of Eacine, Wis., 
and most of it was kept under the writer's observation. Varying 
amounts of black- leg prevailed on the seed plants, but in no case was 
a high percentage of pods infected. As noted before, the most seri- 
ously diseased lot, No. 2-18, when tested in the greenhouse showed 
primary infections on approximately 2 per cent of the plants. Un- 
less otherwise stated, the seed was disinfected by the writer. It should 
be noted that in the cabbage sections where these observations were 
made, seed is sown in open beds about the first week of May, while 
transplanting is done as a rule between June 15 and July 5. Where 
possible, a survey of the seed beds was made before transplanting 
was begun, and final notes were taken in representative fields at the 
end of the season. 
RESULTS IN 1918. 
All of the fields under observation in 1918 were located at Racine, 
Wis., and were grown from seed which had been treated with a 1 : 256 
formaldehyde solution for 30 minutes. Seed beds were sown about 
April 25. When a survey of the beds was made on June 14 the dis- 
ease was already quite prevalent. Most of the transplanting was 
done between June 15 and June 30. There was no reason to believe 
that infection had originated otherwise than by way of the seed, since 
most of the beds were on soil new to cabbage or on which the crop 
had not been grown for several years. The rainfall records for this 
section (fig. 1) show that previous to June 14 the weather had been 
favorable for the rapid spread of the disease from primary centers. 
As a result of the early spread of the fungus in the seed bed, the 
disease became very destructive as the season progressed. This de- 
velopment was confined largely to the home-grown seed, in spite of 
the fact that this had all been treated. A summary of the amount of 
disease in five representative fields at the end of the season is given 
in Table VIII. A typical field grown from this seed as it appeared 
at the end of the season is shown in Plate I, A. It was clear from 
this season's results that treatment with a 1 : 256 f ormaldehyde solu- 
tion does not successfully control the disease when sufficient rainy 
weather prevails to bring about the dissemination of the fungus in 
the seed bed. 
