Johnpma, i have heard the first year for apple trees can be difficult until they develop better roots, perhaps next year it will be better.
What fertilizer if any should you use on rootsocks, some of mine did not really grow at all like 6" (that was do to a poor root sytem when I uprooted and transplanted them)
2019- RO
2018- 25 taps made 8 gal syrup.
2017- 25 taps -built a 2x3 flat pan, and a fuel tank arch for it. 335 gal 7.34gal syrup.
2016- 15 taps, 4.3gal syrup boiling on cinderblock arch 3 roasting pans, 1 redneck trash can with a pot, and a turkey fryer.
2015- 4 taps 44 gals of sap made 2.25 gal of lite syrup.