Relation of Root Condition, Weather, and Insects to the Management of Jack Pine

Beginning in 1937 widespread mortality and decadence occurred in stands of jack pine in northern Minnesota. Ecological studies of the crowns, roots, and rate of growth of thirty-seven trees indicated that lack of soil moisture was the basic cause of the difficulty, although defoliation by budworms and sawflies undoubtedly increased the damage. A very marked deficiency in rainfall during the preceding 20 years, with severe drought at various times and high temperatures during periods of no precipitation, resulted in great mortality of feeding roots and played a major role in decadence. Since jack pine does not recuperate after it has once begun to stagnate, the author recommends the removal of all trees that are obviously not "earning money" at the first opportunity, particularly in periods of moisture deficiency.