Salix (bebbiana)

Greg Fenchel USDA NRCS - Los Lunas Plant Materials Center 1036 Miller Street, SW Los Lunas, New Mexico 87031 (505) 865-4684 (505) 865-5163 (fax) llunas@nmsu.edu http://plant-materials.nrcs.usda.gov/nmpmc

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Family Scientific Name:	Salicaceae
Family Common Name:	Willow family
Scientific Name:	Salix bebbiana Sargent
Common Name:	Bebb's willow
Species Code:	SALBEB
Ecotype:	Apache-Sitgraves National Forest, Arizona
General Distribution:	S. bebbiana is found througout the northern states and across Canada, south in the western U.S. to Texas, New Mexico, Arizona and California.
Propagation Goal:	plants
Propagation Method:	seed
ProductType:	Container (plug)
Stock Type:	One Gallon Tree Pot, 4"x4"x14"
Time To Grow:	1 Years
Target Specifications:	Consolidated root mass sufficient to prevent root ball disintegration during out-planting. Height: 1.4 to 1.9 m<br> Caliper: 12 mm
Propagule Collection:	Identification of female clones is needed for wildland collections. The most critical factor in the collection of viable Salix seed is frequent observation of catkin development. For this reason, establishment of stock plants in the nursery provides significant advantages over wild-land collections. Catkin harvest is typically planned to coincide with the appearance of cotton emerging from partially opened capsules (Schreiner 1974). We have harvested high percentages of viable seed if we are able to harvest at this point in capsule opening. It might be preferable to wait until the capsule are almost fully open, but spring winds can disperse the seed very quickly once the capsules reach this stage and much seed can be lost instantly. The female catkins are placed in paper sacks to capture seed as the capsules open during drying. Seed dispersal usually only takes a few days in a room with dry air and normal working temperatures. If the number of catkins collected forms a layer one or two catkins thick in the sack, the seed will disperse easily without much oversight. If a thick layer of catkins is placed in the sack, frequent turning and mixing of the sack will be required to facilitate uniform drying and seed release. Collection in plastic bags may be acceptable for very brief periods, but the catkins need to be transferred to paper sacks or drying racks as soon as possible to prevent moisture buildup and subsequent decomposition.
Propagule Processing:	Salix seed can be cleaned using a methodology similar to that described by Schreiner (1974) for Populus seed using an air stream and soil screens. A compressed air source and a set of soil screens in a series from top to bottom of 250 æm, 500 æm, 125 æm are employed; the dry catkins containing partially open capsules are placed between the 250 æm and 500 æm screens. A jet of compressed air is blown through the top screen in a swirling fashion; the seed is dislodged and remains on the 125 æm screen with the cotton and empty catkins remaining in the 500 æm screen.
Pre-Planting Treatments:	Stratification: None. Sow cleaned seeds as soon as possible after collection.
Growing Area Preparation/ Annual Practices for Perennial Crops:	Greenhouse 70 o F (21 o C) day, 55 o F (13 o C) night during winter, maximum summer temperature 85 o F (29 o C) with evaporative pad cooling. Mini-plug Irrigation A watering bench with mini-sprinklers automatically waters plug trays once a day in early morning. The watering bench is covered with a copper-coated fabric (Texel Tex-Rr Forestry fabric) to reduce root egress from the plug cells; this fabric covers a filter fabric (Dewitt soil separator fabric) which acts to pull excess water out of plug cells via capillary water movement. The strategy of willow seed propagation typically employed at the New Mexico Plant Materials Center involves germination in "mini-plug " trays containing 512 cells each 14 mm x 14 mm x 29 mm. We rely on mini-plugs because of space restrictions on our automated watering bench, which precludes large-scale germination in larger containers such as Ray Leach Super Cells. In the case of species with poor germination percentages, the use of mini-plugs can save considerable space my minimizing the area consumed by empty cells. However, the extra transplanting step definitely increases labor and material costs. In the case of willow seed, which generally has high germination percentages, the space saving advantage is minimal. The germination medium we use is a standard sphagnum peat moss and perlite mix of fairly coarse texture (Sunshine #1) (we do not use so-called plug mixes). The coarse texture allows the small Salix seed to infiltrate between the particles of peat moss, allowing optimum aeration, moisture, and light. One of the more difficult tasks is the seeding of the cells by hand. The very small size of Salix seed (about 1 mm in length and 0.3 to 0.5 mm in width) makes precise seed dispersal difficult. The addition of diluent (e.g. grit, perlite) of similar size might be of some benefit in achieving more precise sowing by hand. The seed is usually sufficiently clean that an automated seeder typically used for bedding plant seed of similar shape and size would probably be effective if very-large scale seeding was envisioned. The plug medium surface must be kept continuously moist; germination of willow seed is often apparent after one or two days as noted by the swelling and separation of the cotyledons. Thinning of seedlings will be required and is usually performed at the time of mini-plug transplanting or after transplanting into the next container size (e.g. Super Cells) when the seedlings are of sufficient size to make clipping feasible. The goal is to have the Super Cell seedlings ready to move outside in early May after the last freeze but before excessively hot outdoor temperatures. In the outdoor nursery, larger seedlings may require watering every day, smaller seedlings generally every other day. Final Container Type and Volume: One gallon tree pot, 4"x4"x14" (10 cm x 10 cm x 36 cm), 173 in3 (2.83 l) volume. Growing Media: Commercial nursery canning mix of aged screened softwood bark, pumice, and sphagnum peat moss.
Establishment Phase:	The Super Cell seedlings in the greenhouse are watered with soluble fertilizer at every other watering. The fertilizer solution is Peters Peat Lite Special 20-10-20 at a rate of 200 mg/l nitrogen. Thinning of seedlings down to one per container can occur during this phase, usually when the seedlings are 2 to 4 cm tall.Ray Leach Super Cell - 10 in.3 (164 ml) volume, 1.5 in. (3.8 cm) diameter, and 8.25 in. (21 cm) depth. Growing Media: Mix of 2 parts Sunshine #1 or #2 with 1 part perlite. 6 lb (2.7 kg) of controlled release fertilizer (CRF) Osmocote Plus 15-9-12 (3-4 month release) incorporated per cubic yard (0.765 m3) of mix. For plants started in the greenhouse during spring, 5-6 month release CRF is used, but for summer grown material 3-4 month release CRF is incorporated. Planting Technique from Mini-plugs into Intermediate Container The filled Super Cells are dibbled to provide a hole for the mini-plug seedling. The mini-plug seedling root ball is removed using a flat powder spatula with a blade about 6 mm wide and 30 mm long attached to a handle. The blade is plunged along the side of root ball and the seedling plug is levered out of the cell. The plug is dropped into the dibbled hole and the media is pressed around the root ball with fingers. Top watering firms and fills any voids around theplug. If excessive numbers of seed have germinated, excess seedlings can be cut off during the plug transplanting process or later after the seedlings are well rooted. Establishment Phase: The Super Cell seedlings in the greenhouse are watered with soluble fertilizer at every other watering. The fertilizer solution is Peters Peat Lite Special 20-10-20 at a rate of 200 mg/l nitrogen. Thinning of seedlings down to one per container can occur during this phase, usually when the seedlings are 2 to 4 cm tall.
Active Growth Phase:	Fertigation continues as described above. Hardening Phase: The goal is to have the Super Cell seedlings ready to move outside in early May after the last freeze but before excessively hot outdoor temperatures. In the outdoor nursery, larger seedlings may require watering every day, smaller seedlings generally every other day. Final Container Type and Volume: One gallon tree pot, 4"x4"x14" (10 cm x 10 cm x 36 cm), 173 in3 (2.83 l) volume. Growing Media: Commercial nursery canning mix of aged screened softwood bark, pumice, and sphagnum peat moss. Planting Technique: Transplanting into treepots usually occurs in the late summer of the first year or late spring of the second year. The treepots are filled with media and dibbled with a Super Cell planting dibble. Controlled release fertilizer (CRF) is top-dressed at planting or soon thereafter. For pots transplanted in late spring, a 5 to 6 month delivery CRF is used. Seedlings transplanted later in the summer receive a 3 to 4 month delivery CRF at a rate of about 15 g per pot. The treepots are supported in cages 36 in. x 36 in. x 8 in. tall (91 cm x 91 cm x 20 cm) constructed of 4 in. x 4 in. (10 cm x 10 cm) wire mesh fencing; each cage holds 81 pots. Establishment Phase: Watering frequency in this phase in usually three times a week for riparian species. Plants are typically grown without shade. Rapid Growth Phase: Watering frequency can be as often as every day for very large riparian plants with substantial leaf areas. Hardening Phase: The watering frequency is reduced in late September to early October to promote hardening-off. The treepot cages are surrounded by straw bales before winter to lessen temperature fluctuations and provide some insulation for the root systems.
Hardening Phase:	The goal is to have the Super Cell seedlings ready to move outside in early May after the last freeze but before excessively hot outdoor temperatures. In the outdoor nursery, larger seedlings may require watering every day, smaller seedlings generally every other day. The seedlings are fertigated about once a week with Peters Peat Lite Special 20-10-20 at a rate of 200 mg/l nitrogen.The watering frequency is reduced in late September to early October to promote hardening-off.
Harvesting, Storage and Shipping:	The treepot cages are surrounded by straw bales before winter to lessen temperature fluctuations and provide some insulation for the root systems.

Citation:

Dreesen, Dave. 2003. Propagation protocol for production of Container (plug) Salix bebbiana Sargent plants One Gallon Tree Pot, 4"x4"x14"; USDA NRCS - Los Lunas Plant Materials Center Los Lunas, New Mexico. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2024/07/01). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.