Isolate activation

I am hoping to 'activate' some isolates by inoculating them into rhododendrons and then re-isolating them from the plant after infection has occurred in an attempt to remind the isolates how to be virulent. Some times we have isolates that have been maintained for so long in culture that they start to behave strangely or they stop sporulating for example. This is a technique to re-activate them before using them in experiments.