When are buds a problems?

[Octo]

I have 30 red maples. Most of them were nearly completely dry this year. The four trees that produced nearly 30 gallons of sap (wow) are still running, but 2 trees have red buds which are getting larger. They are still closed. When should I stop collecting?

[SPILEDRIVER]

personally i taste the sap everyday when i collect on any tree i think is getting close to budding.there is a very odvious taste change in the sap.there allso is in most cases a color change in the sap.i just pulled a bunch of taps off silver maples that had changed overnite,the taste and smell were terrible!i have some reds tapped allso but there still good.