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Recent studies have shown that the time-consuming step of 

 using a mortar and pestle can readily be circumvented by using 

 a razor blade incision to obtain inoculum. The new technique 

 is relatively easy. A razor blade is used to slice the leaf 



sample just below and parallel to the leaf surface, thereby 



2 

 exposing wounds about 3.0 cm . Immediately after cutting, the 



wounded orchid leaf surfaces can be gently rubbed by hand onto 



the leaves of indicator plants. If the wounded surfaces are 



dry, they can be misted slightly with water before inoculation. 



As in juice inoculations, the leaves of indicator plants should 



be rubbed firmly but gently to prevent damage, which could 



interfere with test results. 



Most assayists rub the two cotyledonary leaves (or the 



first set of true leaves) of young Cassia seedlings, whereas 



for Gomphrena , the fifth or sixth pairs of true leaves are 



inoculated. A fresh cut of the orchid leaf sample should be 



made for each Cassia cotyledon or Gomphrena leaf rubbed to 



assure an abundant supply of inoculum. Before proceeding to 



the next orchid sample, a fresh razor blade or an old one that 



has been sterilized should be used. Sterilization can be done 



conveniently by dipping the razors into 70% ethanol and 



flaming them. After inoculations, excess orchid leaf juice and 



Carborundum can be gently rinsed from the inoculated leaves 



with water. As might be expected, symptoms observed on 



indicator plants inoculated by the razor blade method are 



