Until the roots die they are putting out juglone. Even after the tree is all dead it will take a year or two for the concentration of juglone to go down. You can probably plant right away though, as long as you avoid having roots right next to any new trees. I did that and the apples did fine.

Scott

Yes, if you plant next to a root it will die. Right now the stump is not growing roots, so if you have cleared the hole of roots (and added some organic matter) you will be OK. good fermenting OM (NOT compost) produces jug lone half lives of order one week, which is all you need.

Next year as the new tree roots push beyond the hole you may get unlucky as one rootlet encounters a hot spot. Apples are particularly sensitive and I lost a few to BW. It does not hurt to sever the biggest shallow roots with a hand saw near the stump and/or near the new hole. I have done it many times, when the soil is soft from rain, the hand saw penetrates the soft soil with surprising ease.