PLANT BACTERIA, VOL. 2. 



PLATE 13. 



Cucumbers showing various stages of bacterial wilt due to Bacillus tracheiphilus. 

 Photographed by writer July 13, 1893, on a hill-side at Anacostia, D. C: Fig. 1 (top), healthy vines for comparison with diseased plants 

 on same terrace. Fig. 2, primary and secondary wilt. Leaf-blades toward base of stem (left) have been destroyed by direct infection 

 (beetles) and bacteria have penetrated into main axis. Leaves toward apex of stem have wilted as result of disturbed water-supply 

 due principally to occlusion and destruction of vascular bundles in stem. Fig. 3. only two turgid leaves remain; petioles and stems 

 were still green and normal in appearance. Bacteria filled the spiral vessels of main shoots with a white viscid slime. Fig. 4 

 (bottom), no sound leaves; stems beginning to shrivel. 



