Visually Grade the Seedlings: Bareroot

Bareroot longleaf pine seedlings are a different animal then containerized and need to be recognized as such. Although nursery seedbed density, handling, and planting considerations are important, initiation of height growth appears to be most strongly related to seedling size at the time of planting.  Research has shown that trees with root collar diameters (RCD) greater than 7/16 inch had acceptable growth with at least 87% out of the grass stage after 3 years. On the contrary, bareroot seedlings with RCD less than 7/16 inch were slow to initiate height growth and a large percentage was damaged by brown spot disease.

Bareroot longleaf pine seedlings should be visually graded using the following criteria:

 

Roots

Preferred
bareroot seedling root system should have:

  • root collar diameter of at least 0.4 inches
  • at least six primary lateral roots that are slightly over 1/16 inch or more in diameter
  • a highly fibrous root system (this attribute is often lacking when lifting practices are poor)
  • reddish, brown in color
  • A well developed stout taproot at least 6 inches long.  If the taproot has been severed by root pruning, the severed end should be callused over.

Cull
seedlings if roots:

  • show signs of freeze injury
  • show signs of unhealed wounds where the roots have been damaged in lifting
  • are black in color indicating that they are dead or dying

 

Needles

Preferred
seedling plugs have needles:

  • medium to dark green color in color
  • six to eight inches long (clipped needle)
  • with the presence of numerous fascicles

Cull
seedlings if needles are:

  • mostly yellowish or orange in color

 

Root-Weight Ratio

(root dry weight/seedling dry weight)

Preferred
bareroot seedlings are:

  • ideally samples that are oven-dried, cut at the root-collar and weighed should have a root-weight ratio of about 40 to 50% (but this measurement is rarely measured)

Cull
seedlings if:

  • the root-weight ratio is much lower than 40%

 

Diseases & Pests

Preferred
bareroot seedling should:

  • have no evidence of pest problems

Cull
seedling if the following are observed:

  • extensive brown spot
  • rhizoctonia blight foliage
  • fusiform rust swellings at root collar
  • root rot