Editing Conifer cone (section)

===Crop potential===
Cone crop potential can be predicted in various ways. An early indication of a potential crop can be a period of abnormally hot, dry weather at the time of bud differentiation, particularly if the current and preceding cone crops have been poor (Nienstaedt and Zasada 1990).<ref name="nien5">{{Silvics |last1=Nienstaedt |first1=Hans |first2=John C. |last2=Zasada |volume=1 |genus=Picea |species=glauca}}</ref> Estimates of cone crop potential can be made by counting female reproductive buds in fall or winter, and an experienced observer can detect the subtle morphological differences and distinguish between reproductive buds and vegetative buds (Eis 1967b).<ref name="eis2">Eis, S. 1967b. Cone crops of white and black spruce are predictable. For. Chron. 43(3):247–252.</ref>

White spruce seed collection is expensive, and collection from cone caches of [[red squirrel]]s is probably the cheapest method. The viability of seed from cached cones does not vary during current caching, but viability drops essentially to zero after being in caches for 1 or 2 years.<ref name="wagg">Wagg, J.W.B. 1964. Viability of white spruce seed from squirrel-cut cones. For. Chron. 40(1):98–110.</ref> Collection of cones in seed orchards has been facilitated by the counter-intuitive technique of "topping" and collection of cones from the severed crown tops at one-third the cost of collection from untopped trees and without decreasing cone production.<ref name="slay">Slayton, S.H. 1969. A new technique for cone collection. USDA, For. Serv., Tree Plant. Notes 20(3):13. (Cited in Nienstaedt and Zasada 1990).</ref><ref name="nien1">Nienstaedt, H. 1981. Top pruning white spruce seed orchard grafts does not reduce cone production. USDA, For. Serv., Tree Plant. Notes 32(2):9–13. (Cited in Coates et al. 1994).</ref>