i8 



BACTERIA IN RELATION TO PLANT DISEASES. 



Fig. 9.' 



green" cane. It is not a sign peculiar 

 to this disease, but appears in diseases of 

 an entirely different nature. The writer 

 saw well-marked cases of it at the Har- 

 vard Gardens, on the Soledad Estate near 

 Cienfuegos in Southern Cuba, in the 

 progeny of canes im- 

 ported from the East 

 Indies, but there was 

 no accompanying yel- 

 low bacterial ooze. 

 Possibly this disease 

 was Sereh. In order 

 to be sure one is deal- 

 ing with the gum- 

 disease, one must find 

 ft i the yellow bacterial 



slime in the bundles. 

 This is usually an 

 easy task, except in 

 the case of very resis- 

 tant canes. When one 

 is in doubt samples of 

 the suspected canes 

 should be steamed 

 and then examined 

 (Clark). 



A very conspic- 

 uous sign of the dis- 

 ease in the "common 

 green" cane used for 

 the writer's first set 

 of inoculations was 

 striping of the leaves. 

 In the inoculated 

 ijtwN? leaves white or yel- 



lowish-white stripes 

 extended upward and 

 downward from the 

 pricks. In places, in 

 the white stripes, 

 there were very often 

 rust-brown spots and 

 streaks. Later these 

 became reddish- 

 brown and finally 

 dull-brown and dead, 

 but the etiolation 

 always preceded the 

 Fig. lo.f drying out. Similar 



c< 



t 



*F ig. 9. Cobb's disease of sugar-cane : Plants 6, 8, and 1 2 stripped of leaves to show abnormally short internodes 

 and zigzagging of shoot-axis on itself in efforts to grow through the gummy inclosing leaf-sheaths. These plants are 

 shown in pis. j and 3. Nos. <> and u have sent out basal shoots. The bacterial cavity in fig. 4 was from No. 6. 



fFiG. 10. Common purple cane stripped of leaves to show abnormal pushing of buds. Plant No. 38, inoculated 

 May 5, 1903, photographed Aug. 8, 1903. 



