4^2 Journal of Agricultural Research voi. iv.no. s 



bacteria, as shown by microscopic examination and by poured plates. 

 The plants then outgrew the disease. While not conclusive, these 

 results did not contradict my supposition, since the organism plated 

 from tobacco {Nicotiana spp.) and tomato often gives no more marked 

 results when inoculated into old plants. 



FURTHER CROSS-INOCULATIONS 



A virulent strain of B. solanacearum obtained from tobacco from 

 Creedmore, N. C, during the summer of 19 14 was then available for 

 comparison, and inoculations were made with this into nasturtiums of 

 the tall variety by means of needle pricks from young agar subcultures. 

 After 10 days all plants showed one or more wilted leaves and an abun- 

 dance of the characteristic adventive roots near the point of inoculation 

 (PI. LXV, fig. i). A month later one of these stems had produced ad- 

 ventive roots at intervals from 7 inches above the pricks to 20 inches 

 below them, and in one case where the stem hung near the ground they 

 were 3 inches long and had taken hold in the soil. Bacteria were present 

 the entire length of the stem, which was now entirely leafless. Inocula- 

 tions into dwarf nasturtiums produced a more rapid wilt but no adven- 

 tive roots. 



On young tobacco, prick inoculations with the nasturtium organism 

 caused in five days an internal dark streak (visible on the surface) run- 

 ning several inches up and down the stem from the point of inoculation 

 and the wilt of one or two leaves, but the plants always recovered. 

 Check pricks produced no effect. 



Inoculations with the nasturtium organism into very young tomato 

 plants resulted in the rapid and complete wilt of the plants (PI. LXVI, 

 fig. i). The entire vascular system became gorged with bacteria. 

 Poured plates gave pure cultures of Bacterium solanacearum, as deter- 

 mined by cultures on typical media and by successful reinoculations into 

 both tomato and tobacco plants. 



TESTS ON OTHER PLANTS 



A variety of plants were tested for susceptibility. Prick inoculations 

 were made with both the Creedmore tobacco organism and the nastur- 

 tium organism into pelargoniums, soy beans (Glycine hispida), and 

 lettuce (Lactiica sativa), all with negative results. Owing to the fact that 

 Honing * in Sumatra has reported this disease on several composites 

 and in young teak trees (Verbenaceae) , inoculations were made on hot- 

 house ageratum and on common cultivated verbena. Both became dis- 

 eased but rather slowly. After 10 days the ageratum showed distortion 

 of the leaves, one half being paler and smaller than the other, and after 



• Honing, J. A., Een geval van slijmziekte in de djattibibit. Meded. Deli Proefstat. te Medan, Jrg. 7. 

 Afl. I, p. 12-15. also Naschrift, p. 59, 1912. See review in Smith, Erwin F., Bacteria in relation to plant 

 diseases, v. 3, p. 254. 



