612 SCOTT S. PAULEY AND CLIFFORD E. AHLGREN 



In most mass selection programs, the seed is bulked before sowing in 

 the nursery. In this study, identity of the "mother-tree" lines has been 

 maintained in the nursery. The lines will be evenly distributed through- 

 out the test site using a randomized complete block design with 1-tree 

 plots. Identity of the seedlots beyond this point will not be maintained 



The planting will consist of 100 blocks or replicates, each block 

 containing 1,000 plants. One-half of each block will be planted in 1972, 

 the other half of each in 1974. Planting will be on 3x3 ft spacing in 

 anticipation of high early mortality from rust infection. 



To protect the plantation from fire loss, each group of 10 or 20 

 blocks (replicates) will be surrounded with firebreaks. A deer-proof 

 fence with a minimum life of 15 years will surround the plantation. The 

 fence will be installed in 1971. 



Treatments to Hasten Flowering 



Effects of fertilizers, interspecific grafting, and possibly other 

 treatments to hasten flowering will be tested on a few replicates. Suc- 

 cessful treatments will be applied to surviving trees in the screen test. 

 Favorable results of such treatments would shorten the time to Phases II 

 and III. 



PHASE II. - ESTABLISHMENT OF CLONAL SEED ORCHARDS 



This phase of the project will be initiated as soon as sufficient 

 flowering occurs among trees of the screen test. Seed produced by random 

 crossing may be used for commercial planting but only a 12- to 15-percent 

 genetic gain in rust resistance may be anticipated. This gain may, how- 

 ever, be augmented at this stage by selecting a small number of the best 

 trees (rust free, vigorous and otherwise desirable), asexually reproducing 

 them as clonal lines by grafting and establishing them in seed orchards. 

 These orchards could be established on good sites outside the high rust 

 infection zone (to reduce pollen contamination) and managed for. seed 

 production. 



Although the primary objective of this phase would be to increase seed 

 production for commercial use, there are important additional advantages: 

 (1) establishing the best trees into clonal lines will insure survival of 

 at least a good sample of the screened trees in the event some catastrophy 

 eliminates the screen test planting; and (2) additional breeding material 

 will be available for the production of ¥i plants in Phase III. 



PHASE III. - FULL-SIB FAMILY SELECTION AND RECURRENT SELECTION 



This phase of the project will be initiated concurrently with Phase 

 II, in about 15-20 years. 



Selected screen test trees will be crossed and their offspring, 

 dentified by parentage, will be established in a replicated progeny test 

 i a high infection zone. As these full-sib families reach sexual 

 iturity, surviving family lines will be rogued of the least promising 

 dividuals. In terms of rust resistance, this will mean elimination of 



s that are severely cankered but survived. Selection at this 

 :age may also favor the most vigorous or otherwise desirable individuals 

 t show high resistance to the rust. 



