The Minnesota Tree Improvement Cooperative (MTIC) has led efforts to improve the quality of tree seed across northern Minnesota and Wisconsin for more than twenty-five years. Currently, more than 45 seed orchards are intensively managed for seed production. Six tree species are utilized in the MTIC: white and black spruce, tamarack, red, jack, and white pine. Improved white spruce seedlings grow 25-30% faster than seedlings derived from wild stands. Jack pine seedlings have moderate improvements for height (10-12%) and are vastly improved with respect to stem form. White pine orchards are established with families containing putative rust resistance. The MTIC has progressed into second generation material for jack pine, black spruce, and white spruce. Ongoing projects include breeding white pine for improved disease resistance and establishing improved first-generation orchards of red pine and white spruce.
The goal of the MTIC is to develop a tree improvement program that produces seedlings for reforestation in the upper Midwest. Selections for first-generation orchards are based primarily on increased volume growth. Stem straightness and branch angle are being incorporated into advanced-generation selections. Disease resistance is being incorporated into a breeding program for eastern white pine to improve its survival against white pine blister rust, Cronartium ribicola. The goal of this breeding program is to elucidate and enhance mechanisms of resistance by integrating promising genotypes into existing orchards. This project is supported by several research grants administered by the University of Minnesota’s Department of Forest Resources.
A broad genetic base is maintained for each species to reduce inbreeding and to ensure that orchard seed is adapted to a variety of biotic and abiotic conditions. As the program is advanced through tree breeding, future-generation orchards will continue to maintain rigorous standards for diversity and seed-production to provide a reliable seed source for current and future reforestation efforts.