Mechanical aids to improve the speed and sensitivity of plant virus diagnosis by the biological test method

Modifications to a Pollahne leaf sap press are described which allow it to be used for bioassay purposes without risk of cross contamination. Constructional details are given for manual and automatic versions which utilise hot and cold water to sterilise and cool the working parts of the press. Two compressed air guns which are used together to inoculate indicator plants, are also described. The first incorporates carborundum powder into a jet of air and causes controlled wounding of plant epidermal cells to permit virus entry. The other applies sap inoculum as a finely divided spray to the wounded plants. The variables affecting the use of these guns are discussed. Improvements in sensitivity of 64 fold, compared to manual methods were obtained and potential to develop this to 500fold demonstrated.