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Proceedings of Past Forest Nursery Association Meetings:

Impact of Aphid Damage in a Bareroot Nursery and Seed Source on Survival and Growth of Outplanted White Fir Seedlings in the Sierra Nevada
John D. Stein
1994: Moscow, ID
A species of a woolly fir aphid, Mindarus kinseyi Voegtlin (Homoptera: Aphididae), has been responsible for dead apical buds on 25% to 65% of the white fir seedlings harvested for outplanting at a bareroot nursery in central California since 1987. In 1990 and 1991, undamaged and damaged progeny from seeds collected at elevations of 1500 m or higher were outplanted on Iron Mountain in the central Sierra Nevada. Nursery seedlings originating from the Eldorado National Forest that meet or exceed nursery cull standards, despite being injured by M. kinseyi, were more vigorous than undamaged Eldorado seedlings during the first year of outplanting. In 1990, the origin of seed sources had a significant effect upon seedling survival during the first field season. The local seed source originating from the Eldorado National Forest, seemed to be better adapted for survival when seedlings were drought stressed. Eldorado seedlings had the highest survival, whereas seedlings from the Klamath and Stanislaus National Forests had the highest mortality. Aphid damage and seed origin in 1990 did not have a significant effect upon growth response; however, in 1991, the interaction of aphid damage and seed origin was important. Aphid-damaged seedlings from the Eldorado and site one of the Stanislaus National Forests grew significantly taller than undamaged seedlings from the Eldorado and the Klamath National Forests. Aphid-damaged seedlings from the Eldorado and Klamath seed sources had significantly more stem volume than undamaged seedlings from the Eldorado and site one of the Stanislaus seed sources. The contrast in the growth response for undamaged and aphid damaged seedlings from the Eldorado may indicate a difference in an induced hardiness.
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