Nov. 1, 1925 
Bacterial Spot of Oowpea and Lima Bean 
845 
rather large, bleached, dried areas' surrounded by a claret-brown 
border (pi. 3, B). In old lesions the central tissue dries and may 
crack or drop out. Frequently the central tissue is invaded by 
fungi. 
The lesions are not in any way delimited by the veins; on the con¬ 
trary they frequently extend markedly along the veins (pi. 2, D; pi. 
4, D and E). Linear leaf lesions have been noted extending along a 
vein a distance of 4 to 6 cm. If young leaf lesions are mounted in 
a drop of water on a slide and cut across with a scalpel, the bacteria 
may readily be seen under the microscope, oozing out in cloudy 
masses from the cut edge, especially from the region of the veins. 
Infection occurs very readily on young growing leaves, and con¬ 
siderable distortion, curling, tearing, and puncturing of the leaves 
may be caused by the growth stresses (pi. 2, B; pi. 3, B). Lesions of 
early inception may thus become maroon-bordered slits and tears in 
the leaf lamina or along its margin, and vein lesions may cause curva¬ 
ture and crinkling. Lesions on a vein may cause a yellowing or 
bleaching (pi. 2, C) of distal portions of the leaf. 
Lesions on the young leaves of cowpea seedlings under greenhouse 
conditions first become visible as small sunken pits or craters in the 
epidermis (pi. 5, C), which are translucent in transmitted light but 
soon become greasy or water-soaked and later claret-brown in color. 
At first such lesions are visible only on the lower side of the leaf 
and as a rule remain more extensive and more conspicuous there 
than on the upper side of the leaf. Older lesions assume the buff 
center and the claret-brown border and are surrounded by a narrow 
light-green halo. Also very small claret-brown lesions occur on the 
stipules (pi. 6, D). The symptoms on lima-bean leaves, described 
by Tisdale and Williamson ( 2Jf)i are essentially similar to those on 
cowpea leaves, as are also the lesions on catjang leaves (pi. 2, A). 
On the leaves of artificially infected velvet-bean plants the lesions 
were dark brown to black, with some tendency to be delimited by 
the veins (pi. 6, F). Natural infection of velvet-bean leaves pro¬ 
duced lesions more closely resembling those on cowpea. These were 
irregularly circular, with a tan center and a dark-brown marginal 
line, and were surrounded by a light-green or yellowish halo in the 
living tissue. On tick trefoil the lesions showed a tan to light-brown 
center, with a narrow, reddish-brown marginal line, and were sur¬ 
rounded by a light-green or yellowish halo in the living tissue 
(pi. 5, B). 
On the cowpea stems and petioles the lesions are more or less oval, 
1 to 5 mm. long, and Victoria lake in color (pi. 6, D and E). The 
center is usually sunken, and there may be water-soaked tissue 
above and below the lesion. Frequently the lesions are much 
longer, especially on the petioles, and large sunken lesions are formed 
on the epicotyls and hypocotyls of seedlings (pi. 3, F and G). Simi¬ 
lar stem and petiole infection also occurs on lima beans. Catjang 
leaves have been noticed to break off at petiole lesions. 
The lesions on cowpea and catjang pods are irregularly circular and 
1 to 8 mm. in diameter, and morocco red, claret brown, maroon, or 
Victoria lake in color (pi. 3, A). The^larger lesions often have a 
sunken center and a water-soaked outer border. Infection of young 
pods results in a marked constriction of the pod at the point of 
infection, and usually in an abnormal bending of the pod at that 
