The ecology of subalpine fir relative to broom rust was investigated. Broom rust infections were most common in trees growing on limestone soils, and seldom occurred on trees growing on basalt soils. Even though plant moisture stress was consistently higher in the plants from limestone soils, the studies indicated that moisture stress is not the major factor causing infection. The amounts of available magnesium and phosphorus were much lower in the limestone soil. It is postulated that the higher plant moisture stress of subalpine fir growing on limestone soils may aggrevate the lack of nutrients and be a contributing factor to the susceptibility of subalpine fir to broom rust. Even though the study raises more questions than it answers, management prescriptions relative to this disease can be proposed. Pruning and burning of diseased branches should be evaluated as a possible method to control broom rust on subalpine fir. This species must be better managed because of its strategic position on watersheds and recreation sites of higher elevations.

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