Fast-growing trees can thrive in Maine

Apologies are due to readers in Houlton, LaGrange, Bangor, Corinna and Hampden and to anyone else who read my column on the Miracle Tree and wondered whether it can be grown in Maine. The sad truth is that it cannot.

The giant Leucaena is a tropical species, and one reason it is capable of such phenomenal growth is that given adequate moisture the plant grows throughout the year. I know of no tree in Maine that equals Leucaena’s prolific rate of growth.

There are, however, several species that perform very well compared to native trees. Hybrid poplar is the fastest growing tree for our area, putting on up to 2 inches of trunk diameter per year. The wood is of no great value, other than for boiler fodder or pulp, and the short-lived tree should be harvested after eight to 10 years.

Stump shoots quickly replace the first cutting, and no other species offers as high a biomass production in Maine, in terms of cords per acre per year.

Japanese Larch is a somewhat slower grower, but still much faster than either the native larch (tamarack, hackmetack) or most other softwoods. It makes a good landscape subject as well, with golden bark in winter and soft, light green foliage in summer. Both the larch and poplar are frequently offered at an inexpensive price by county Soil Conservation Services in the spring.

A third option for quickly covering bare ground with woody plant material is the hybrid willow. Eight feet of growth is possible the first year and 20 the second. A little judicious pruning promotes bushiness, making these willows ideal for a quick hedge. Miller Nurseries (5060 West Lake Road, Canandaigua, N.Y. 14424) carries hybrid willow.

A final note on the Miracle Tree comes from Jim Edelblut, University of Maine campus representative of the Peace Corps, who had direct experience planting the giant Leucaena in Senegal. A trained forester, he says that the idea of planting a single species of tree to solve all the problems of tropical deforestation made him cringe. But the Leucaena does all that it is claimed to and more. Edelblut stresses the tree’s ability to host nitrogen fixing bacteria in its roots, thus adding fertility to the soil. Intercropping the trees among food crops such as peanuts, corn and millet provides a `no-cost’ fertilizer.

A Dover reader wants to know where he can obtain the rock wool I mentioned in a recent column, so that he can try it as a soil amendment for growing New Guinea impatiens. I recommend that he contact Greenhouse Supply of Maine, a newly established supply business in Orono (tel. 866-7919.)

A Castine reader complains that her avocado suffers from rusty lower leaves, which eventually fold themselve against the stem, `petticoat fashion.’ New growth seems healthy.

From the leaf enclosed in the letter I suspect the plant is short on fertilizer. Avocados are tricky to grow, however, and the problem could just as easily be a root. I remind all readers that sick plants can receive expert diagnostic attention through the University of Maine’s Cooperative Extension program. Each county maintains an extension office with one or more agents, and there is a diagnostic clinic in Orono (telephone 581-3880) which helps to identify insect and disease problems for commercial growers and homeowners alike.

Michael Zuck of Bangor is a horticulturist and the NEWS garden columnist. Send inquiries to him at 2106 Essex St., Bangor, Maine 04401.