That term is not an accurate name for any product that I can think of. I think I would contact the county Extension Office and see if they could diagnose the problem from a photo you take in or e-mail to them. If you can at least determine if it is a root problem or a stem canker or a leaf disease then it would be easier to suggest a control. I have not know the Japanese blueberry to have any particular disease problems so the comments of the previous owner sound fishy to me.
My first concern would be to make sure the soil is moist but not kept soggy wet as both extremes cause problems for plants.
Thanks for the question. Please stop in again soon with additional questions if you have more symptoms to report after having examined the plants closely to see just where the problem appears to be on them.
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