142 
Journal of Agricultural Research 
Vol. XXV, No. 3 
This description characterizes the disease under consideration in this 
paper more nearly than it does the blight caused by B. phaseoli , as the 
two diseases have been seen at Madison, Wis. In 1898, Sturgis ( 8 ) 
described a bacterial disease of lima beans in Connecticut which he 
attributed to B. phaseoli E- F. S. However, his description of the disease 
more nearly characterizes the spot disease than the blight. Manns (5) 
has also described a bacterial organism which is pathogenic upon certain 
legumes, including lima beans. He did not describe or illustrate the 
disease of lima beans, but his report upon cultural and morphological 
characters precludes the possibility of the two organisms being the 
same. 
SYMPTOMS 
Since the bacterial blight caused by B. phaseoli also attacks the lima 
bean, it is well to differentiate between this and the bacterial spot. The 
spots of the two diseases appear quite different from the beginning and 
can be easily distinguished even when the two occur on the same leaf or 
pod as they frequently do. 
bacterial blight 
The blight, caused by B. phaseoli E- F. S., attacks all the parts of the 
lima bean plant which are subject to the spot disease. The lesions on all 
parts of the plant are very similar to those produced on similar parts of 
the common bean (Phaseolus vulgaris) by B. phaseoli. Young lesions on 
the leaves are water-soaked, and the tissues surrounding them soon dry 
out, causing large blighted areas which generally extend to the leaf mar¬ 
gin. Exudate appears on the lower surface of the young lesions and dries 
out, forming a thin film or scale. The blighted areas are not as brown in 
color as the bacterial spot (PI. 1, A), but the small veins near the spots 
are often red. On the pods and stems the young lesions are also water- 
soaked and accompanied by films or crusts of yellow exudate. The 
lesions extend through the walls of the pod and attack the seed. A thick 
yellow exudate is often produced both outside of and beneath the seed 
coat. 
BACTERIAL SPOT 
On the leaves where this disease is very conspicuous, it is characterized 
by brown to purplish-colored lesions, which vary from somewhat irregular 
to almost circular shapes (PI. 1, B). The spots are never at any time 
water-soaked. At first they appear as small brown points on the upper 
surface and enlarge very rapidly for the first few days. On the lower sur¬ 
face the young spots are depressed and the margins are a lighter color than 
on the upper surface. As the spots enlarge, the centers dry out and turn 
gray or straw colored and the margins remain a glistening, purplish red 
color. Single spots are usually from 1 to 3 mm. in diameter and may be 
quite generally scattered over the leaf surface, although they are occa¬ 
sionally grouped and confluent, especially on the first leaves. When 
spots thus coalesce, lesions several millimeters in diameter are formed. 
In the latter case the centers of the lesions break out and give the leaves 
a ragged appearance. The lesions are usually smaller and more regular 
in shape on the upper leaves. On the King of the Garden variety the 
spots cause a curling or distortion of the young leaves. The disease also 
occurs on the veins and petioles where it appears as characteristic reddish- 
brown or glistening caramel-colored streaks. The streak usually occurs 
