Training espalier query

[Phytopthora]

I am trying to train an apple as a 3 tier espalier. I have the first tier secured but I only had two shoots available for the second tier so I tied one and pruned back the main stem to just below the second tier wire in the hope that I will get two further shoots (one to tie in and the other to grow upward to the top tier). Hopefully the attached picture will help). My question is have I done the right thing? If not how should I best rectify the situation?
The rootstock is 106.

Thanks

[FB.]

When a tree won't branch how you'd like, you just have to try anything logical to make it happen.
Pruning - as you've done - may work, especially if you follow up with some tip-pinching if you get another strong upright shoot but no side shoot or a weak side shoot.
By pinching out the tip of a shoot the roots will send some of their water and nutrient supply to buds near to the pinched-out tip, causing those buds to sprout, or, from summer (June) onwards, fruit spurs may form below pinched-out tips in addition to, or instead of, side shoots.

As a backup, you could try getting a Stanley knife and cutting a 1-3mm high by 5-10mm wide strip of bark off, just above a bud which you'd like to sprout into a side branch. Known as 'nicking and notching'.

It temporarily (until it heals) blocks and causes redirection elsewhere of the flow of sap from buds above, removing the growth-suppressing effect of the hormones coming down from buds higher up the tree.

[Phytopthora]

Thank you FB

I had heard of "nicking and notching" but had forgotten the terms. I will now be able to look it up. Isn't one above the bud and the other below?
What is the best time to carry out this operation?
Should I allow the branches to continue growing in length until they reach the desired length?

Do you grow a lot of fruit yourself?

[FB.]

Thank you FB

I had heard of "nicking and notching" but had forgotten the terms. I will now be able to look it up. Isn't one above the bud and the other below?
What is the best time to carry out this operation?
Should I allow the branches to continue growing in length until they reach the desired length?

Do you grow a lot of fruit yourself?

Yes, one is above and one is below.

Nicking and notching will work best if done in winter or spring*. On strong-growing trees it might work in summer too, but weaker-growing and dwarf trees usually aren't growing much by that time.

My definition of winter is December-February and spring is March-May.

[FB.]

Do you grow a lot of fruit yourself?

Yes, I have a lot of fruit, ranging from rhubarb to currants to tree fruits. I especially 'collect' old, rare, triploid apple varieties and grow them on big rootstocks such as MM111 and M25 which helps overcome my terrible soil.
Ironically, my soil is shallow, sandy-gravelly-chalky, low-fertility, free-draining and droughty, yet Phytopthora manages to prey on fruit trees, probably under drought stress.

I'd manage to grow a lot more more if Phytopthora hadn't destroyed so many of my fruit trees.