Step 4 Choosing high quality longleaf pine seedlings

Part C; Visually Grading Bareroot Longleaf Pine Seedlings (go back)

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 then 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 then 7/16 inch were slow to initiate height growth and a large percentage were damaged by brown spot disease.

Bare Root Seedlings:

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 root are:

•show signs of freeze injury

•show signs of unhealed wounds where the roots have been damaged in lifting

•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 eigth inch clipped needle

•the presence of numerous fascicles

CULL seedlings if needles:

•most needles appear yellowish or orange in color

Root-weight Ratio (root dry weight/seedling dry weight):

PREFERRED bareroot seedlings have a root:shoot ratio of:

•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).

TOP-CLIP NEEDLES if shoot:root:

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

Diseases and Pests:

PREFERRED bareroot seedlings should:

•no evidence of pest problems

CULL seedlings if the following are observed:

•extensive brown spot

• rhizoctonia blight on foliage

•fusiform rust swellings at root collar

•root rot