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

• How cones are handled determines seed quality.
• How cones are handled determines seed quantity.

• 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

• 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).

• 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.

• 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.

• 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.

• Fill with water until it overflows at the spout and drains down to its natural level.
• Discard this water.

• 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.

• 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).

• 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).

• 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

• 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

• 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

• 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.