The Bugwood Network

Cone Handling Practices

Robert Karrfalt - Director, National Tree Seed Laboratory, 1159 Forestry Building, Purdue University, West Lafayette, IN 47907-1159

Karrfalt, R. 2001. Cone Handling Practices In: D.J. Moorhead (ed.) Proceedings of the Longleaf Pine Container Production Workshop. Jan. 16-18, 2001. Tifton, GA. USDA Forest Service and University of Georgia.

Cone Handling Practices

An Important Early Step to a Good Crop of Seedlings

  • How cones are handled determines seed quality.
  • How cones are handled determines seed quantity.
Determining When Cones Can Be Collected

  • The calendar is a good start but only a start.
  • Specific gravity measurements are needed to be sure cones are mature enough to produce good seeds.
    • Do it within 20 minutes of removing cone from tree.
    • 19 of 20 cones need to be below .89 spg.

Specific Gravity

What is it?

  • Indicator of how dry the cone is.
  • Weight of cone compared to weight of equal volume of water.
    • Measured by water displacement.
    • 1 gram of water equals 1 ml or 1 cc.
  • Just a number (not ml, cc, or grams).
What do we see?

  • Specific gravity = 1 cone just floats at surface.
  • Specific gravity < 1 cone floats partly out of water.
  • Specific gravity > 1 cone sinks.
  • May or may not be related to color.
    • Some cones very green.
    • Some cones more yellowish grenn.
How will we measure it?

  • With graduated cylinders.
  • Required a large cylinder (2 liters).
    • Sometimes hard to find.
    • Not graduated very finely.
      • Makes it maybe hard to read.
      • Maybe compromises accuracy.
The Home Made Cylinder

  • Materials
    • 3 or 4 inch toilet flange.
    • 18 inches of 3 or 4 inch pipe.
    • 1/2 inch street elbow.
    • 1/2 inch nipple, of suitable length.
    • 12 to 18 ounce plastic cup.
    • 100 ml graduated cylinder.
    • PVC cement.
  • Tools
    • 1/2 pipe thread tap.
How to use the home made cylinder - step 1

  • Fill with water until it overflows at the spout and drains down to its natural level.
  • Discard this water.
Using the home made cylinder - step 2

  • Place the cone gently down into the water and catch the overflow in the drinking cup.
  • Measure and record this overflow in the 100 ml cylinder. (This is the cone weight.) (100 ml).
  • Discard this water.
Using the home made cylinder - step 3

  • Gently submerge the cone below the water surface and catch the overflow in the drinking cup.
  • Measure and record the overflow in the 100 ml cylinder. (12 ml).
Using the home made cylinder - step 4

  • Add the two volume measurements together. (This is the weight of the equal volume of water.) (100 + 12 = 112).
  • Divide the weight of the equal volume of water into the weight of the cone. (This is the specific gravity) (100/112 = .89).

Picking Cones


  • Find locations with adequate crops.
  • Maybe prepare the stands with mowing, burning, understory removal.
  • Have adequate numbers and sizes of containers.
    • Bags and large boxes both work well.
    • Do not overfill containers especially bags. (1/2 full).

  • Have adequate post harvest storage.
    • Enough room to keep cones out of the weather.
    • Adequate ventilation to allow cones to dry at some rate.
    • Protect from wind and predation.
  • Arrange with Crop Improvement to have seeds certified to source or level of improvement. (Start early enough).
The Actual Event

  • Shake trees.
  • Collect wind falls.
    • Be careful of maturity.
    • Hurricane cones are usually of poor quality.
  • Harvest timber at cone maturity.
  • Do not leave cones on ground overnight.

Observed Cone Storage Mistakes

Things NOT to do

  • Store cones in piles. (Heating and molding).
  • Store out in the rain. (Seeds sprout).
  • Store in shallow racks. (Seeds and cones spill out).
  • Allow seeds to fall out the bottom of the drying rack. (Seeds lost and damaged).
  • Air dry in overfilled sacks. (Lost yield).

Proper Cone Storage

Things to do

  • Store with ventilation reaching all cones.
  • Store in adequately sized containers.
    • 1/2 full sacks.
    • Racks with high enough sides (at least one open cone diameter).
  • Place fine mesh fabric or wire on drying rack bottoms.
  • Carefully mark all seed lots/prevent mixing.
  • Protect cones from rain and predators.

Cone Drying

The actual event

  • Do it within 30 days of cone harvest.
  • Do it within 24 to 48 hours of kiln time.
    • Longer periods stress the seeds.
    • Ideal RH is about 30%.
  • Be prepared to test seed moisture and dry seeds.
    • Seeds are shed from the cone at high moisture.
    • A small home made dryer can do the job.
    • Test the seed moisture with an electronic meter.
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Last updated on Tuesday, July 09, 2002 at 10:16 AM
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