Authored by Austin Heine
Austin Heine is the Reforestation Advisor North Carolina and Virginia.
Austin has been a valuable member of the ArborGen team since January 2023 and is currently a Ph.D. candidate in Forestry with an interest in Improving Seed Yields for Mass Control Pollinated Loblolly Pine at North Carolina State University.
Cone harvest is currently taking place for several species of pines in seed orchards across the southern United States. These cones have been forming on the trees for the last ~18 months following their pollination in the spring of 2024. Since that time, the orchard managers have performed their responsibilities of managing these orchard trees and protecting these cones from insect damage to developing cones and seeds inside of these cones. That is the part that I want to focus on here though, what exactly is inside of each of these pine cones?
Loblolly pine seed following extraction from cones and removal of the wing. This is how seed will look before being sent to the nursery for sowing in February of 2026.
On average, a loblolly pine cone has the potential to produce about 160-170 seed per cone (Heine et al. 2023). For the sake of this article, we are going to say that each cone is producing 100 seeds. If you are replanting your property on a 10’ x 10’ spacing (representing 435 trees per acre), 100 seedlings will be able to reforest approximately 1/4 acre. The major decision for you to make prior to planting is whether you want to plant seed from an open-pollinated cone or a controlled-pollinated cone (MCP®). In a nutshell (well maybe pinecone is more appropriate here), your choice decides what DNA is packed inside of the cone and how that DNA will drive the future production, disease resistance, stem form, and ultimately financial return of your future forest for the next 25+ years. It is a major decision that should not be taken lightly!
Open-Pollinated Cones
The 100 seed inside of an open-pollinated cone all share the same superior female contribution as they all are cones that have been collected from the same tree. They do not, however, all have the same father. In the spring of 2024 when those cones were forming and your car was yellow and covered in pollen, those cones were also being covered in pollen from the pollen cloud. On average, about 4 pollen grains make it into the pollen chamber for each future pine seed (Matthews and Blalock 1981), and once inside, those pollen grains grow inside of the cone with one pollen tube ultimately completing fertilization and becoming the father.
Loblolly pine pollen grains and developing pollen tubes imaged under a microscope.
The assumption made by tree breeders in producing the performance sheets that show the expected performance of these open-pollinated seeds is that ~70% of the pollen that was used to create that cone came from within a seed orchard and 30% of the pollen came from outside of the seed orchard. Bringing this back to our pine cone producing 100 seeds and replanting your ¼ acre, that means that 30 out of the 100 trees has an unknown father. Was the father’s DNA good or bad? We won’t know for sure. What we do know though, is that this is the reason that open-pollinated cones produce forest stands with a much wider range in performance within the stand, lower percent sawtimber, and can have slower growth and more visible defects such as infection from fusiform rust when compared with controlled-pollinated trees. One potential positive is that they are more genetically diverse as they have many fathers.
An open-pollinated stand of AG-373 in Berkeley County, SC showing within stand variation and reduction of future value due to both loss of stems to fusiform rust disease (center) and forked stems (upper left).
Controlled-Pollinated Cones (MCP®)
In the mass production of controlled-pollinated cones, pollination bags were installed onto the branches of the known superior mother tree prior to the pollen cloud forming. These bags isolated the cones inside from outside pollen and allowed orchard managers to inject the bags with pollen of a known superior father parent. Going back to our 100 seed pine cone, that means that this cone will have 100 seeds with a known superior mother and known superior father. Additionally, this MCP® cross has already been tested by ArborGen’s product development team, so that we know the offspring from this specific combination of parents is going to perform well. Contrasting this with the best potential from the open-pollinated cone, the 70 seeds that were pollinated from within the seed orchard, there are still many combinations of potential fathers and the performance of these combinations of mother x father is very likely unknown. When ArborGen MCP® seed is produced, the result for you is a stand with superior growth, disease resistance, and stem form. The performance is also expected to be more uniform than the open-pollinated stand because MCP® is composed of only one superior male that has also been tested and proven to perform well when bred to that superior mother. Through tree breeding and testing, we have done the heavy lifting for you and prepacked each of these seeds with the DNA that is needed to deliver the best financial returns to you. MCP® stands are not perfect and will have some defects as there is still a range in performance (think about the difference between your brothers and sisters) and there are still environmental factors that can lead to stem defects; however, your chances of success and higher return have already been greatly improved. Do you want to gamble and hope that combination of males making up that 100 seed pine cone are good or do you want to stack the deck in your favor? In a market with an ever-increasing focus on chip-n-saw and sawtimber with defect free stems, the value that MCP® seedlings can deliver cannot be stressed enough.
MCP® Select planted in 2013 at 622 trees per acre (TPA). Shown here at 12 years old, thinned once, average DBH 7.4” and average height ~60 feet.
Literature Cited
Heine, A.J., T.D. Walker, J.B. Jett, F. Isik, and S.E. McKeand. 2023. Pollination bag type affects ovule development and seed yields in Pinus taeda L. Forest Science 69(2):187-199.
Matthews, F.R., and T.E. Blalock. 1981. Loblolly pine pollen grain counts by ovule dissection. P. 276-278 in Proceedings of the 16th Annual Southern Forest Tree Improvement Conference. Blacksburg, Virginia, USA.
