As tapping panel dryness of the rubber tree developed in response to various stress treatments, significant changes in invertase and polyphenol oxidase activities, total sugars and total solids in the latex were found to be associated with the intensive tapping and ethephon treatments. These changes appeared to be related more to the exhaustion of the laticifer system 9over-exploitation) than to the basic causes of drynes. They were unreliable predictors of dryness in situations where the dryness was not accompanied by increased yield output, as exemplified by the pin-pricking stress treatment. In the early stages of the stress treatments, latex proline and copper content increased with all the experimental treatments attempted, irrespective of whether yield output was increased. .These results suggest that an increase in latex proline or latex copper might serve as a warning indicative of incipient or impending dryness.