Figure 10. — These typical ponderosa pine seeds are from a very heavy seed crop in 



central Idaho. 



Ripe cones have a specific gravity of 0.80 to 0.86 in central Idaho (Maki 1940). 

 The degree of ripeness can be tested by dropping closed cones into kerosene or a half- 

 and-half mixture of kerosene and raw linseed oil. When most of the cones from a tree 

 float, the seeds from that tree are ripe. The float test should be applied only to 

 freshly picked cones. 



Seed storage. — The infrequency and irregularity of ponderosa pine seed crops make 

 seed storage necessary in a program of artificial regeneration. Fortunately, very 

 heavy cone crops generally produce high percentages of good seed (fig. 10), which can 

 be stored for use during intervening years. 



Ponderosa pine seeds have been stored successfully for 14 years when dried to less 

 than 10 percent moisture content and placed in sealed containers at a constant tempera- 

 ture near 32° F (Curtis 1955b). Other workers (Allen 1957, Barton 1954, Schubert 1955) 

 have reported successful storage at temperatures from 32° F to 0° F, although tempera- 

 tures near 32° F were the best. 



Direct Seeding 



Direct seeding has never been used extensively in the northern Rockies although 

 some areas are seeded nearly every year. Summaries of the results of extensive early 

 tests report many failures and a few successes (Wahlenberg 1925; Maki 1938). Contrib- 

 uting factors in most successes were believed to be thorough elimination of competition 

 and favorable weather patterns (Wahlenberg 1925) . Many of the early seedings were 

 attempted on very dry sites where planting had failed previously. The knowledge gained 



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