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(Lawson and Brannigan, in press). Orchidists inexperienced at 

 rub-inoculation should include a few noninoculated Cassia and 

 Gomphrena seedlings in their controls. Sometimes other 

 factors, such as pollution damage, can induce lesions on Cassia 

 or Gomphrena plants which can be confused with those caused by 

 virus ( Lawson and Brannigan, in press). Inoculating some indi- 

 cator plants with an orchid sample known to be free of virus is 

 recommended so that possible inoculation damage can be 

 distinguished from viral lesions. 



