422 
Journal of Agricultural Research 
Vol XXIX, No. 9 
Fawcett ( 8 ) states that A. brassicae 
causes much damage to cabbage in 
Florida some seasons. Higgins (11) 
likewise reports this disease as having 
been very destructive on collards in 
Georgia for several years. Harter 
and Jones (9) state that black leaf- 
spot causes considerable damage to 
cabbage and collards in this country 
and in Europe. Chupp (3) records the 
fact that on Long Island in the cab¬ 
bage-seed growing district Alternaria 
always does injury as a seed-pod spot. 
The literature, both domestic and 
foreign, is replete with references to 
Alternaria leaf spot on cabbage and 
other cruciferous hosts. Notwith¬ 
standing its prevalence, the disease is 
usually of minor importance on cab¬ 
bage in the field, since it ordinarly 
occurs only on parts of the host which 
have become low in vitality. With 
the exception of that by Puttemans 
(13 ), no reference to the occurrence of 
this disease on the curd of cauliflower has 
been found. No doubt the brownrot 
has been prevalent for a long time 
without having received much atten¬ 
tion from scientists, due in part at 
least to the fact that until recent years 
little time has been given to the study 
of transit diseases. As stated above, 
the disease of the curds seems to be 
most prevalent on cauliflower from the 
Pacific coast. This does not mean 
that it is necessarily more com¬ 
mon or destructive there. The writer 
has sought many times for this 
disease on the heads of cauliflower in 
the vegetable-growing section about 
San Francisco during the season of 
1922-23 but never found it except on 
heads that were overmature or that 
had been cut from the plants and left 
lying on the ground. The growers in 
the Los Angeles section claim that 
this disease appears during the latter 
part of their shipping season. While 
the leafspot stage was not common 
in the San Francisco section it was 
very prevalent about Los Angeles dur¬ 
ing the season of 1922-23. Probably 
cauliflower from no other region is 
subjected to conditions so favorable 
for the development of the disease as 
is that from the Pacific coast during 
the period of transit across the con¬ 
tinent to the eastern markets. Never¬ 
theless, the writer has seen the typical 
brownrot lesions on cauliflower from 
New York. Badly diseased heads 
have also been obtained from the 
Washington, D. C., city market. 
Some of these were locally grown 
•while others were said to have come 
from Florida. There is little doubt 
that the brownrot may be found 
wherever cauliflower is grown, pro¬ 
vided it has been subjected to proper 
environmental conditions. But it ap¬ 
pears to be of little importance except 
as a transit trouble. 
A few figures from the reports of the 
Bureau of Agricultural Economics 
indicate some of the losses caused by 
this disease in transit (Table I). 
Except under conditions of high 
humidity, the disease develops slowly 
and causes greater loss by badly dis¬ 
figuring the leaves and heads than by 
actually destroying them. Under field 
conditions the leaves may be so badty 
affected that the vitality of the plants 
is lowered and the size of the heads 
consequently reduced. Other micro¬ 
organisms such as soft-rot bacteria and 
species of Fusarium and Rhizopus also 
enter the lesions and initiate other 
types of decay. 
SYMPTOMS OF THE DISEASE 
In the writer’s experiments the 
disease first became evident on the 
leaves, petioles, and stems of young 
plants as small dark brown to almost 
black spots about 1 mm. in diameter. 
The ultimate size and character of the 
lesions depended to some extent on the 
humidity and on the nature of the tissue 
affected. Three types of lesions usually 
developed on leaves of cauliflower 
inoculated in the greenhouse (PI. 
1 and 2). On the lamina the spots 
remained small (about 1 mm.) and 
dark brown, developing but little 
after the first three days (Pis. 2, b), 
or they enlarged, forming lesions 
somewhat circular in outline from 0.5 
to 1 cm. or more in diameter and gray¬ 
ish to brown in color. Scattered 
promiscuously about the center of 
these spots were minute black areas 
where the fungus was fruiting. These 
spots sometimes coalesced, forming 
large irregular areas, often involving 
half or more of the leaf (PI. 1, A, C; 
PI. 2, A, B, C, D). The diseased tissue 
shaded off from brownish to yellow 
and then to the normal green of healthy 
EXPLANATORY LEGEND FOR PLATE 1 
A and C.—Early Snowball cauliflower seedlings grown in the greenhouse, showing the type of lesions 
produced by Alternaria brassicae on the leaves and petioles. Photographed 3 days after inoculation. 
Natural size 
B and D.—Seedling cabbage leaves grown in the greenhouse, showing the circular to irregular, light-colored 
lesions caused by A. brassicae as well as the small, dark-colored ones, the latter being limited largely to the 
veins. About natural size 
