Question
Our home is in zone 5a/6b far western suburbs of Detroit.  It is sitting on 5 acres of what used to be an alfalfa field, I keep it mowed, but now mostly weeds and clover and whatever wild grasses come up. It is 100 sand soil (so much so that we have in our family room the only stone that could be found when they dug the basement).  Drainage is NEVER an issue.  We have several Blue Spruce trees dotting the acreage, and will be adding a few hardwoods (6-8ft maples /oaks) just to lose the house in a hayfield look.  2 questions: 1. what should I use to 'ring' the spruces and hardwoods so that I can mow around them with the tractor- cedar mulch, rubber mulch, wood chips?  I don't care about what it looks like, I just want to keep weeds from coming up under the trees and make mowing easier. 2. what can I use to keep the deer from eating the new growth off the spruces (and I assume the hardwoods)?  We have an abundance of deer and they already killed a white birch that I had planted 2 years ago...

Thanks,
Mark Caswell
Milford, MI

Answer
Hello, Mark:

There are several products on the market, and I have tried none of them...Here are a few links anyway:

http://deerscram.com/
http://www.liquidfence.com/
http://deer-repellent.net/

It helps to pick a tree or plant that the deer don't care for to begin with.  These following lists are from The Univeristy Ag Extension of New Jersey:

Trees that deer seem to hate:
American Holly-Ilex opaca
Bottlebrush Buckeye-Aesculus parviflora
Dwarf Alberta Spruce-Picea glauca 'Conica'
Japanese Black Pine-Pinus thunbergiana
Katsura Tree-Cercidiphyllum japonicum
Mimosa-Albizia julibrissin
Paper Birch-Betula papyrifera
Pawpaw-Asimina triloba
Pitch Pine-Pinus rigida
Red Pine-Pinus resinosa
River Birch-Betula nigra

The lists are NOT a fool-proof, as a HUNGRY deer will eat anything that is green, as noted by you losing a white birch, even though there are two listed above.  

Unfortunately Maples, Cedar, Pear, Cherry, Cypress, Fir, Sweetgum, Hemlock, Locust, Apple & Oaks are some of the FAVORITE FOOD for deer!!  You might as well also a install a dinner-bell, too.

Here are some shrubs that deer may NOT care for, as well:
Arrowwood-Viburnum Viburnum dentatum
Barberry-Berberis sp.
Bayberry-Myrica pensylvanica
Blue Mist Shrub-Caryopteris clandonensis
Broom-Cytisus sp.
Bush Cinquefoil-Potentilla fruticosa
Butterfly Bush-Buddleia sp.
Common Boxwood-Buxus sempervirens
Daphne-Daphne sp.
Devil's Walking Stick-Aralia spinosa
Drooping Leucothoe-Leucothoe fontanesiana
Fragrant Sumac-Rhus aromatica
Heath-Erica sp.
Heather-Calliuna sp.
Japanese Pieris-Andromeda  Pieris japonica
Japanese Plum Yew-Cephalotaxus harringtonia
Japanese Skimmia-Skimmia japonica
John T. Morris Holly-Ilex x 'John T. Morris'
Leatherleaf Mahonia-Mahonia bealei
Lydia Morris Holly-Ilex x 'Lydia Morris'
Moonglow Juniper-Juniperus scopulorum 'Moonglow'
Mountain Pieris-Pieris floribunda
Oregon Grape Holly-Mahonia aquifolium
Prince of Wales Juniper-Juniperus horizontalis 'Prince of Wales'
Red Elderberry-Sambucus racemosa
Russian Cypress-Microbiota decussata
Russian Olive-Elaeagnus angustifolia
Sweet Box-Sarcoccoca hookeriana  

I didn't cross-check the list with your zone (5b), but at Dave's Garden (http://davesgarden.com/products/gwd/c/2397/) there is a Michigan supplier that also lists "Deer resistant" nursery stock.  Check their list to see if they carry the tree species that you want to plant.

As far as mowing under the pines, I'd suggest a heavy mulching of organics like wood chips, at least 8 to 10 inches thick and extending out from the tree's drip line by at least 2 feet.  You can install a weed fabric first, and htat should buy you a few years of abatement, until the trees have a chance to get bigger.

Hope it helps ~Marc