A method comprise selecting one or more isolation coverings to modulate a development stage by delaying or advancing the development stage of one or more strobilus buds growing on a gymnosperm tree installing the one or more isolation coverings over the one or more strobilus buds while leaving other parts of the gymnosperm tree uncovered and naturally growing and maintaining the one or more isolation coverings over the one or more strobili buds for a time period sufficient to obtain a desired development stage of the one or more strobilus buds. A method of synchronizing the timing of pollen collection from male flowers and female flower receptivity in a gymnosperm tree breeding program comprising: at least one of: (a) advancing a development stage of one or more male strobili on one or more tree(s) in a breeding program comprising installing over one or more male strobilus buds a type of protective covering selected to advance male strobili development, and maintaining the protective covering over the strobili until pollen is generated or (b) delaying a development stage of one or more female strobili on one or more tree(s) in the breeding program, comprising installing over one or more female strobilus buds a type of protective covering selected to delay female strobili development, and maintaining one or more protective coverings over the one or more female strobilus buds until either sufficient pollen is generated in accordance with step (a), or until the majority of uncovered control female flowers are at a developmental stage that is no longer receptive to pollination.
