Everglades Station Mimeo Rpt. 63-21
Bacterial Leaf Spot of Cabbageli
Cabbage growers have long been familiar with dark brown spots of the cabbage
heads, a disease that in some years can cause serious damage to the crop.
Usually it is only the outside or wrapper leaf that is affected. Sometimes,
however, the spots can be found on the inside leaves after peeling off the outer
leaves. The spots on the younger leaves usually do not correspond with those of
the leaf that covered them which indicates that the pathogen has been growing
systemically. Cross sections through the stem of these plants usually showed
darkened vascular bundles; bacteria could be seen both in the vessels and in
the surrounding parenchyma.
From leaf spots and from diseased stem tissue a bacterium was isolated and
identified as Pseudomonas cichorii (Swingle) Stapp. Inoculations made in the
petioles of young potted cabbage plants produced a rapidly enlarging dark spot.
An aqueous suspension of the bacteria sprayed on heading cabbage in the green-
house produced similar spotting as in the field.
P. cichorii has been isolated from escarole, and from ornamental chrysan-
themum. Dr. Thayer has also found that all his isolates from bacterial leaf
blight on celery were P. cichorii. All the isolates taken from celery, escarole,
cabbage and chrysanthemums were pathogenic on cabbage.
1/ Prepared for presentation at the Annual Vegetable Crops Field Day held at
the Everglades Experiment Station May 9, 1963.
/ Associate Plant Pathologist, Everglades Experiment Station, Belle Glade, Fla.
EES Mimeo Rpt. 63-21