Larix (occidentalis)

Kayla Herriman Manager USDA FS - R6 Bend Seed Extractory 63095 Deschutes Market Road Bend, Oregon 97701 kayla.herriman@usda.gov http://fsweb-ochdes.r6.fs.fed.us/seedextractory/ex

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Family Scientific Name:	Pinaceae
Family Common Name:	Pine
Scientific Name:	Larix occidentalis
Common Name:	western larch
Species Code:	LAOC
General Distribution:	Western larch is found from western Montana to eastern Oregon and Washington and British Columbia.
Propagation Goal:	Seeds
Propagation Method:	Seed
ProductType:	Propagules (seeds, cutings, poles, etc.)
Stock Type:	seed processing
Propagule Collection:	Seed cones are usually scattered throughout the higher portion of the crown. They occur randomly on the sides of twigs or branches. They are a one-year cone that is small (1-2 inches long). Cones ripen in August and September. Cones can be collected by using ladders, hydraulic lifts, or by climbing trees, usually just before cones open. Cones are put in burlap or mesh bags.
Propagule Processing:	Pre-Processing – Cones can be opened by placing them in a kiln 100 degrees Fahrenheit for 6 to 10 hours. Cones must cool before processing as pitch will stick to the seed and the machines. Processing – *Note: all processing of LAOC must take place in 60-degree temps or less. This includes tumbling, de-winging, screening, and gravity table. This is to ensure that excessive pitch does not accumulate on equipment or the seed. Extraction: Cones are tumbled to extract the seeds. While tumbling screens are used to remove as much pitch-dust as possible. Smaller lots are hand tumbled/sieved. Large lots, more than 10 bushels tumble over an LMC Vibratory Conveyor Model 3626.5 with screens to create separation. Pitch-dust is being removed in the first barrel, seed in the second and third, and cones traveling off the end of the tumbler. De-winging: Do not de-wing larch until after screening of most of the coarse inert material has occurred. Seed tends to de-wing naturally during the screening process and mechanical de-winging may not be necessary at all. Finishing: Seeds are air-screened, using a Clipper Eclipse Model 324 or Office Clipper. First run: Top screen 11 round, 2nd screen 12 round, 3rd screen 12 round, bottom screen is blank. Air ranges from 25-35. The top screen is scalping needles, cones scales, twigs and the air is focused on removing wings. Screen sizes could vary depending on the seed size and inert material present, but large rounds are used for this run. Second run: Use the same settings, but the top screen is covered with a solid insert over half of the area. This reduces the amount of time/opportunity the inert material has to go through the screen. The goal of this run is to remove more inert material and focus on improving the purity and fill percent of the seed lot. Screen sizes and air varies by lot. Some smaller lots may need to be finished on the Mater Continuous Seed Blower (CSB) to help to increase fill percent or remove pitch. Small Westrup gravity table may work to isolate pitch. If not able to separate pitch on a machine, it must be floated out. Note: often LAOC lots are so small you may end up floating the entire lot if you cannot isolate the majority of the pitch first. Floating: Float large seed lots outside. Fill basin to no more than 1/3 full of seed then add water to within 1” of top. Drain off pitch and water, then refill and drain at least 2 more times until most of the pitch is separated. Run seed through the basin with water into a bread tray and spread to a 1” or less layer. Dry immediately. Add this seed back to the “finished” portion from the gravity table only after it is thoroughly dried. To float small lots fill container to no more than 1/3 full of seed then add water to within 1” of top. Drain off seed and water over a sieve, then refill and drain at least 2 more times until most of the pitch is at the bottom of the container and the seed is in the sieve. Dry immediately. Add this seed back to the “finished” portion from the gravity table only after it is thoroughly dried.
Other Comments:	Average Number of Seeds per Pound: 127,657 Average percent purity: 97 Average percent fill: 88 Estimation of PLS/bag: 22,917 *PLS calculated using fill% *This LAOC information comes from 122 processing records at the Bend Seed Extractory from collections seasons 1990 through 2019.

Citation:

Herriman, Kayla . 2022. Propagation protocol for production of Propagules (seeds, cutings, poles, etc.) Larix occidentalis Seeds seed processing; USDA FS - R6 Bend Seed Extractory Bend, Oregon. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2024/07/02). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.