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HYBRID POPLARS ATTRACTING ATTENTION OF STATE'S LANDOWNERS
Imagine trees that grow from rootstock to 20 feet or more by the second year!
A show plot of hybrid poplars at this summer's Farmfest near Redwood Falls drew heavy interest from a variety of visitors:
- Farmers and investors researching a new cash crop;
- Homeowners interested in a quick-growing windbreak;
- Landowners searching for a way to cash-crop their CRP acres;
- Curiosity seekers wondering how a tree can grow so fast.
Along with solar energy and windmills, hybrid poplars got a boost in the late 1970s during the oil embargo. University of Minnesota and state foresters began evaluating thousands of crosses of the genus Populus (aspen, cottonwood, poplar) for their energy producing potential and other characteristics.
According to Steve Von Groven, a DNR forester at Mora, researchers have identified eight very promising hybrids that are resistant to both insects and disease and grow fast. These hybrids mature in 8-15 years and yield 3-5 cords/acre/year.
The Farmfest demonstration plot has first-year trees that stand about 3 feet tall and a second-year stand that towers to 20 feet. These trees are spaced 4 feet apart and will be thinned to 8 feet next year. The stand is so thick it is difficult to walk between the trees.
If you've ever had difficulty counting annual rings of a felled tree, you'd marvel at the rings of hybrid poplar. On a 10-year-old cross section I examined, the rings were more than a half inch thick; a 10-year-old tree, therefore, exceeds 10 inches in diameter!
Hybrid poplars are being encouraged as an agricultural crop in part because Minnesota's supply of aspen is inadequate to support our state's expanding paper manufacturing industry.
At present prices, hybrid poplar won't produce a return equal to corn or soybeans. After 10 years of growth, a plantation of hybrid poplar should yield 40 cords/acre and have a value of $1,200. Cost to establish an acre of hybrid poplar is approximately $300, and some maintenance costs will be incurred during the first couple of years for weed control (by the third year, trees shade out weeds).
One possible scenario that may be economically viable is to plant hybrid poplars on CRP (Conservation Reserve Program) acres and harvest the crop at the end of 10 years when the CRP contract is over.
Skeptics of hybrid poplars include landowners who planted windbreaks of fast-growing Lombardy poplars 20 or 30 years ago and then watched them die prematurely from canker disease the starts in the upper branches and works its way down. The hybrid poplars available from Lee Nursery in Fertile, Minnesota and Schumacher Nursery in Heron Lake, Minnesota, are not susceptible to canker disease, according to Von Groven. He recommends ordering cuttings of at least three different clones to spread the risk of possible disease or insect infestations.
Interest in hybrid poplars for windbreaks is widespread in rural Minnesota because so many windbreaks were destroyed last December when the ice storm tore apart ash and other grove trees. While poplars drop their leaves like other deciduous trees, they provide enough of a wind barrier to trap snow at the perimeter of a building site. For windbreaks, Von Groven suggests planting three rows of poplars spaced 8 feet apart - closer if you are willing to thin them later).
Hybrid poplars will not perform in extremely wet or dry soils, or where soil pH exceeds 7.5, Von Groven says.
I don't recommend hybrid poplars for the average urban lot where you're looking for shade or a stately specimen tree. For these purposes, plant a red or swamp white oak, sugar or red maple, river birch or linden.
But if you are searching for a fast-growing windbreak...or if you want to reap a return on your investment in trees 10 years from now...or if you want to create heavy cover for birds and wildlife...then hybrid poplars may be a good choice.
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PUTTING DOWN ROOTS:
A Delightful Blend of
Gardening Wisdom, Wit
and Whimsy
$10 + $2 for shipping
by Cliff Johnson |
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