Interspecific Transmission of Mosaic Diseases of Plants 13 



Errors due to accidental contamination 

 There are a number of ways in which contamination may occur. These 

 may be briefly mentioned : 



1. The plant used as the source of inoculum may be affected with two 

 or more mosaics. 



2. The inoculum may become contaminated during the process of 

 preparing it for use. 



3. The instruments (or hands) used in making the inoculation may 

 be contaminated. 



4. The inoculated plant may become infected from some source other 

 than the experimental inoculum. Ways in which this may occur are: 

 by insects; by handling by the experimenter or by visitors; by contact of 

 the injured parts of the plants, as the rubbing together of inoculated leaves 

 or the breaking and rubbing of roots in moving the pots; and by the use 

 of plants from previous experiments where symptoms are masked. 



Errors due to the use of ineffective methods 



It is well within the bounds of possibility that methods which would 

 give good infection with one mosaic or a certain suscept, would fail with 

 a different combination of mosaic and suscept. For example, it is well 

 known that tobacco mosaic can be transmitted by hypodermic injections. 

 Reddick and Stewart (1919) were unable to transmit bean mosaic by 

 this method, although they made many attempts. 



RESULTS OF EXPERIMENTS 



The results of the inoculations with material from different species are 

 presented in tables 2 to 20. These data are summarized in table 21 with 

 respect to the particular mosaic concerned. 



TABLE 2. Inoculations on Datura meteloides 



Mosaic* 



Suscept, source of inoculum 



Number 

 of plants 

 inoculated 



Number 



of plants 



showing 



symptoms 



Type of 

 symptoms 

 observed 



A 



B 



C 



D 



E 



F 



G 



H 



Checks 



Nicotiana Tabacum. 

 Solanum tuberosum. 

 Datura Stramonium 

 Nicotiana glulinosa. 

 Phytolacca decandra 

 Rumex obtusifolius . . 

 Phaseolus vulgaris. . 

 Echinocystis lobata. . 



Own leaves 



Uncertain 

 Uncertain 

 Uncertain 



* For the original source of the mosaic indicated by letters A to H, see pages 3 and 4. 



