The Performance Rating System (PRS) allows a quick and easy evaluation of the tested genetic potential of loblolly pine seedlings. This customer-friendly rating system helps landowners, forestry consultants, tree planters and others to select and use loblolly seedlings with known genetic performance. With the PRS, you now have an easy tool to select loblolly pine seedlings that are most appropriate for your sites and forest management objectives.

The PRS ratings were developed by the Cooperative Tree Improvement Program at N.C. State University with assistance from the N.C. Forest Service. The PRS allows you to assess the potential gains that could be achieved by using genetically-improved loblolly pine seedlings when compared against other loblolly seedlings that are cultivated from wild or unknown seed sources. Over 50 years of forestry research from across the southeastern U.S. went into the development of the PRS rating values and criteria. It is important to note that the actual PRS values shown for a seedling are for comparison purposes only and do not indicate the absolute performance level of a seedling selection on any particular site, or under any particular silvicultural practice. The PRS rating system consists of four parts:

Productivity, rust and stem straightness are compared with wild commercial seedlots from the same deployment region which was used in the field testing conducted by the Cooperative Tree Improvement Program and its members.

There are two deployment regions for North Carolina: Coastal (“Coastal NC”) and Piedmont (“Piedmont NC”). Seedlings from other deployment regions can be planted in North Carolina but there is more risk in doing so.

The Productivity (P) rating estimates the percent of potential genetic gain in tree volume compared with wild seedlings. Estimating a tree’s productivity by means of a volume rating can be valuable for a landowner, since most timber is purchased according to the volume or corresponding weight of that tree.

The Rust (R) rating uses an alphabetic code comparing an estimated forest stand rust infection rate to the wild commercial seedlings. The rating is similar to grades in school: “A” is better than “B,” which is better than “C,” which is better than “D,” which is better than “E.”

The Stem straightness (S) rating estimates the percent of expected improvement compared with wild commercial check seedlings. The same alphabetic grading systems is used, ranging from “A” for best to “E” for worst.

Two examples of PRS ratings for loblolly pine seedlings are shown below:

All loblolly pine seedlings purchased from the N.C. Forest Service will have their PRS rating printed on the seedling bag/box label. Landowners should carefully consider the long term financial investment and greater potential for a healthy, productive forest when evaluating which seedlings to plant. Ask your seedling provider or tree planter to provide the PRS rating for the seedlings being considered for your land, and compare them for the best results. Contact the N.C. Forest Service for more information or visit our Web site, ncforestservice.gov.

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Published in March 2009

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