November 2020 – 1st Edition
Knowing the Annual Minimum Temperature for Your Pine Seedlings is Critical to Survival
Long term forestry research has provided a clear understanding of how Loblolly pine has adapted to local climatic conditions from New Jersey to Texas. Loblolly pine varies in its ability to withstand cold temperatures depending on where the original parent trees were from. This research examined the survival and vigor of loblolly seed sources, or provenances, planted across the South. US Forest Service scientists then developed planting zones to which these provenances are well-adapted. These zones for forestry are a modification of USDA Plant Hardiness zones you may have seen at your local garden center store. The most important climatic variable for pine is the average annual minimum temperature.
Source: “Southern Pine Seed Sources” by R.C. Schmidtling
Extensive research has shown that seedlings can survive and grow well in locations that are up to 5 degrees colder than the seed source origin. In other words, Loblolly Pine seed sources from warmer climates can grow faster as long as they are planted in an area that is not more than 5 degrees colder from the origin of the seed source.
Failure to follow these seed source movement guidelines can lead to catastrophic loss. Planting the wrong seedlings in the wrong geographic area not only threaten initial seedling survival but, even if they survive, the cold temperatures can limit plantation growth due to lack of adaptability. Reports of recent survival problems in northern North Carolina and Virginia suggest that seedlings families were planted in areas with minimum temperatures too low for them. Our Reforestation Advisors use ArborGen’s proprietary FamInfo database that has the Annual MinTemps for every county in every state where loblolly pine can be planted. ArborGen has specific families that have been well-tested for adaptability for these colder areas. You can be sure that your Reforestation Advisor will select the appropriate seedling families adapted to the min-temps occurring in your area to survive and grow well.
Take a look at this article published by the United States Forest Service on “Southern Pine Seed Sources” for more information on why it is critical you know the annual minimum temperature your seedlings can tolerate before planting.
Article by Jason Watson,
Manager, Reforestation Advisors
Good seedling quality is one of the key components of a successful forest regeneration project.
A high-quality seedling will survive prolonged periods of environmental stress and grow well following out-planting. While there have been many definitions of seedling quality over the years, at ArborGen, we tend to follow the bareroot specifications detailed in this graphic from Auburn University Southern Forest Nursery Management Cooperative. We produce seedlings that have a woody stem and secondary needles (needles in fascicles) and a 10 to 12 inch top. We also specify a 6 inch tap root with preferably eight or more primary lateral roots, an average root collar diameter (RCD) of 5mm or more, and a seedling that is free from incidence of insects and disease. These specifications produce seedlings that work well for either hand or machine planting operations. Our container seedlings have similar specifications with the key differences from bareroot being that the root length is limited to the length of the container, and container seedlings have a slightly smaller target RCD of 4 mm.
Seedling quality is a high priority at every ArborGen nursery. The nursery teams routinely monitor seedling health and growth along with soil moisture and fertility to ensure that we produce a quality seedling. In addition, the ArborGen Product Development Seedling Quality Team provides an independent, second set of eyes looking at the quality of seedlings at every nursery. We track seedling growth throughout the growing season, comparing the current season’s growth with previous seasons. We also compare our results with those of the nursery teams to make sure that seedlings are growing at the rates they should be to achieve the proper shoot and root dimensions at lifting. Then in December, our Product Development Team will lift and measure seedling height, diameter, and root length and count root numbers to determine the percentage of trees that meet our specifications. We also ship seedlings to Auburn University for a third independent assessment of seedling quality. Auburn will measure many of the same traits that we do, along with calculating the root weight ratio.
ArborGen Product Development Team members measuring seedling quality at the Blenheim Nursery
Why do we emphasize seedling root collar diameter in our assessments?
A good root system is key to seedling survival. It is like the foundation of a house. It is the support for everything that is going on above ground. A good root system at the time of planting will generate new roots quickly. These new roots are necessary when spring arrives, and the seedling starts new top growth. Without a good root system, there is not enough water and nutrient uptake to support the new top growth, and the seedling is prone to a slow start or may even suffer top dieback. Root collar diameter (RCD) is highly correlated with root mass. So by monitoring our seedling RCD, we are indirectly monitoring root system development. Several research studies over the years have shown the positive link between seedling caliper and bareroot seedling survival like the chart below from David South (1990). Factors such as the quality of site preparation, planting date, planting quality, and weather also affect survival beyond RCD.
Whether you are buying our advanced genetic seedlings such as MCP or Varietals or open-pollinated seedlings, you can rest assured that ArborGen is committed to providing you with the best quality seedlings available.
ArborGen Reforestation Advisor, Geoffrey Hill, shows us what good quality means and what to look for in your seedlings.
High Quality Seedlings at Your ArborGen Nurseries
Loblolly OP Advanced
Available at your Shellman, GA Nursery
Loblolly OP Elite
Available at your Blenheim, SC Nursery
Slash OP Elite
Available at your Bellville, GA Nursery
Loblolly OP Elite Piedmont
Available at your Blenheim, SC Nursery
Loblolly BR OP Select Coasta
Available at your Taylor Nursery in Trenton, SC
Loblolly OP Elite for East Texas
Available at your Bullard, TX Nursery
Seedling Provider Survey
We have a survey circulating that we wanted to open up to the general community.
The survey takes about five minutes and asks about what you look for from a seedling provider.
(If you are a Reforestation Forum member, please use the link you’ve already received from the Forum, instead of the button below.)
Picking Up Your Seedlings
Staying Safe this Planting Season
The lifting season is upon us for our seedling crop. There are hurdles every year, and 2020 seems to be an overachiever in this regard. To keep everyone safe, deliver you the seedlings you have ordered and provide the customer service you expect, we ask for your cooperation in working with our nurseries to make this a safe and productive season.
It is more critical than ever this year to call ahead to arrange pick-up of your seedlings. This will allow our nursery personnel to provide you expedited service in a safe environment.
Some of the changes you may see at the nurseries this season are:
- Limited number of people and transactions inside the office.
- Designated areas and bathrooms for visitors and customers.
- Wear a mask or practice social distancing.
- Look for signage and messaging from your nursery to help make your visit as safe as possible.
- Utilize hand sanitizer when entering the office.
If you are experiencing symptoms or have been exposed to someone with COVID-19, we ask that you do not enter the nursery.
If you have any questions, please do not hesitate to reach out to the nursery you plan to visit.
Thank you for your patience and understanding.
Director, U.S. Nursery Operations
Get in touch with a Reforestation Advisor to explore your options!
Paul Jeffreys, Ph.D.
Western Tennessee, Alabama, and Mississippi
North Carolina and Virginia
Eastern Texas, Southern Louisiana
Florida Gulf Coast, South Alabama
Arkansas, Northern Louisiana, and Oklahoma
Director, U.S. Sales
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Ridgeville, S.C. 29472