How do you know when Sweetcorn is ready?

I'm now at the same dilemma as last year. How can I tell when the Sweetcorn is ready?

There are some who say that it's when the tassels turn brown. Well on some they started brown!
Then there are those who say that it's when the tassels stop being sticky. Some of the new tassels are already not sticky. The rain washed any "stickiness" off them.
There are those who say that you have to pick a cob and test it. That's all very well if you have a field full and can risk losing some of your crop for testing.

I just wish that there was a simple way of finding out.

Meanwhile, the grapes are starting to fill out.

And we upended one of our potato bags to a an extremely disappointing harvest. This is the total of our Red Russets.

Considering that the pallet board is a mere 4 inches across, those 7 spuds are minuscule. Maybe the late frost did more harm to them than we anticipated. Anyway, not all is lost. We do have a few other bags where there is still plenty of foliage. So hopefully we can get some spuds.

But I'd still like to know about the sweetcorn. Or maybe I should just leave them on the stalks to harden and settle for making popcorn.