Question
I purchased and planted 15 7' white pines about 6 weeks ago, the nurseryman where we purchased them led me to believe that I could leave the burlap bag on the tress when I planted them and the tree would grow thru it, I have read several posts that suggest otherwise.  Should I dig them up and remove the burlap?

Answer
Generally the recommendation is to remove the wire , twine and burlap before planting to allow the roots to grow out better.  How fast the burlap decays will depend on the type burlap and the weather conditions in your area. Treated burlap will last a long time and can slow the growth of the tree. The important thing is to make sure the top of the burlap is nor above ground level --this tends to wick water away from the root system and could dry out the roots. IF you can see burlap I would dig down around the tree a couple of inches and cut the burlap down so it is not exposed.  

The soil type the trees are planted in will have some effect on the root system--roots left in burlap planted in heavy clay tend to not grow out as well as if the burlap were removed. This tends to cause the roots to grow in a circle and could chock the root system.

Now saying all this since the trees were planted 6 weeks ago which would have been near the end of the planting ideal season for pines if they are dug up and replanted you will need to be careful that they are replanted right away and the trees are watered. The weather is getting hotter and drier and trees that are planted during these months have a hard time.

I think I would check with the nursery who sold the trees and ask them again about the burlap--if they say to leave it on --ask about their guarantee and how long it is for. IF they guarantee the trees if planted their way I would wait and see and if the trees are not doing well toward the end of the time frame get replacements and take the burlap off before planting them. By not ding welll I mean if the trees are not green but have a light green yellow color and the foliage is not thick they could be root bound. Unfortunately this may not show up the first year so look close to compare these with other pines about the same size.

If you have not done so I would recommend that you mulch around the trees with not more than 3 inches deep of organic mulch not piled up on the trunk. This will help hold moisture around the roots.

In summery--I would cut any burlap exposed down to a couple of inches below the ground level and not dig the trees up but IF they did not suit me toward the end of the guarantee time frame get replacements from the nursery and plant them without the burlap.

I hope this helps.